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1. Drift-harmonic functions with polynomial growth on asymptotically paraboloidal manifolds

Author

Law, Michael B.

Subjects
Mathematics - Differential Geometry, Mathematics - Analysis of PDEs
Abstract

We construct and classify all polynomial growth solutions to certain drift-harmonic equations on complete manifolds with paraboloidal asymptotics. These encompass the natural drift-harmonic equations on certain steady gradient Ricci solitons. Specifically, we show that all drift-harmonic functions with polynomial growth asymptotically separate variables, and the dimension of the space of drift-harmonic functions with a given polynomial growth rate is finite., Comment: 57 pages

Published
2025

2. Concavity for elliptic and parabolic equations in complex projective space

Author

Aryan, Shrey and Law, Michael B.

Subjects
Mathematics - Analysis of PDEs, Mathematics - Differential Geometry
Abstract

We establish a concavity principle for solutions to elliptic and parabolic equations on complex projective space, generalizing the results of Langford and Scheuer. To our knowledge, this is the first example of a general concavity principle outside the constant sectional curvature regime, and in particular, our result partially answers a question raised by Korevaar in 1985 regarding the concavity of solutions to elliptic equations on manifolds with non-constant sectional curvature., Comment: 15 pages

Published
2024

3. Predictors of cost-related medication nonadherence in Canada: a repeated cross-sectional analysis of the Canadian Community Health Survey

Author

Rebic, Nevena, Cheng, Lucy, Law, Michael R., Cragg, Jacquelyn J., Brotto, Lori A., and De Vera, Mary A.

Subjects
Medicine, Preventive -- Methods, Medical care, Cost of -- Analysis, Patient compliance -- Methods, Drugs -- Prescribing, Preventive health services -- Methods, Health
Abstract

Background: In Canada, many patients face substantial out-of-pocket costs for prescription medication, which may affect their ability to take their medications as prescribed. We sought to conduct a comprehensive analysis of the burden and predictors of cost-related nonadherence in Canada. Methods: Using pooled data from the 2015, 2016, 2018, 2019, and 2020 iterations of the Canadian Community Health Survey, we calculated weighted population estimates of the burden of cost-related nonadherence in the preceding 12 months and used logistic regression models to measure the association of 15 demographic, health, and health system predictors of cost-related nonadherence overall and stratified by sex. Results: We included 223 085 respondents. We found that 4.9% of respondents aged 12 years or older reported cost-related nonadherence. Those who self-identified as female, belonging to a racial or ethnic minority group, or bisexual, pansexual, or questioning were more likely to report cost-related nonadherence. Younger age, higher disease burden, poorer health, non-employer prescription drug coverage, and not living in the province of Quebec were associated with cost-related nonadherence. Interpretation: Our nationally representative findings reveal inequities that disproportionally affect marginalized people at the intersections of sex, race, age, and disability, and vary by province. This foundational understanding of the state of cost-related nonadherence may be used to inform potential expansion of public drug coverage eligibility, premiums, and cost-sharing policies that address financial barriers to medication adherence., Prescription medications are necessary for disease prevention and management, particularly for people with chronic conditions; however, they are not always taken as prescribed. The costs of long-term medication use may [...]

Published
2024
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4. Health worker protests and the COVID-19 pandemic: an interrupted time-series analysis/Manifestations du personnel de sante et pandemie de COVID- 19: analyse de serie chronologique interrompue/Las protestas del personal sanitario y la pandemia de la COVID-19: un analisis de series temporales interrumpidas

Author

Sharma, Kartik, Brophy, Sorcha, Law, Michael, and Sriram, Veena

Subjects
Epidemics -- Social aspects, Medical personnel -- Demonstrations and protests
Abstract

Objective To assess the impact of the coronavirus disease 2019 (COVID-19) pandemic on protests by health workers. Methods We conducted an interrupted time series analysis of data from 159 countries for 2 years before and after the World Health Organization classified COVID-19 as a pandemic in March 2020, thus between 2018 and 2022. We produced models examining two main outcomes: (i) the total weekly number of health worker protests globally; and (ii) the number of countries with one or more health worker protests in a given week. Findings In total, there were 18 322 health worker protests in 133 countries between 2018 and 2022. The number of weekly health worker protests globally increased by 47% (30.1/63.5), an increase of 30.1 protests per week (95% confidence interval, CI: 11.7-48.6) at the onset of the COVID-19 pandemic. Furthermore, the number of countries experiencing such protests in a given week increased by 24% (5.7/24.1) following the declaration of the pandemic (an increase of 5.7 countries; 95% CI: 3.5-7.8). Conclusion The pandemic increased the overall level of health worker protests globally as well as the number of countries experiencing such protests. These protests highlight discontent in the health workforce. Given the ongoing global health workforce crisis, understanding and addressing the drivers of health worker discontent is important for global health policy and security. Objectif Evaluer l'impact de la pandemie de maladie a coronavirus 2019 (COVID-19) sur les manifestations du personnel de sante. Methodes Nous avons effectue une analyse de serie chronologique interrompue de donnees issues de 159 pays deux ans avant et deux ans apres la classification, par l'Organisation mondiale de la Sante, de la COVID-19 dans la categorie des pandemies en mars 2020, donc entre 2018 et 2022. Nous avons ensuite elabore des modeles pour deux elements principaux: (i) le nombre total de manifestations organisees chaque semaine par le personnel de sante; ainsi que (ii) le nombre de pays ou le personnel de sante a manifeste au moins une fois au cours d'une semaine donnee. Resultats Le personnel de sante a participe a un total de 18 322 manifestations dans 133 pays entre 2018 et 2022. Le nombre de manifestations hebdomadaires a augmente de 47% (30,1/63,5) a l'echelle planetaire, l'equivalent de 30,1 manifestations supplementaires par semaine (intervalle de confiance de 95%, IC: 11,7-48,6) au moment de l'apparition de la pandemie de COVID-19. En outre, le nombre de pays touches par ces manifestations au cours d'une semaine donnee a augmente de 24% (5,7/24,1) lorsque l'etat de pandemie a ete declare (ce qui represente une hausse de 5,7 pays; IC de 95%: 3,5-7,8). Conclusion La pandemie a entrame une recrudescence des manifestations organisees par le personnel de sante dans le monde, ainsi que du nombre de pays confrontes a de telles manifestations, ce qui illustre le mecontentement qui regne au sein du secteur. Etant donne la crise que connait actuellement le personnel de sante partout dans le monde, s'interesser et s'attaquer aux facteurs de mecontentement des soignants est essentiel pour la securite et la politique en matiere de sante mondiale. Objetivo Evaluar el Impacto de la pandemia de la enfermedad por coronavirus de 2019 (COVID-19) en las protestas del personal sanitario. Metodos Se realizo un analisis de series temporales interrumpidas de datos de 159 paises durante dos anos antes y despues de que la Organizacion Mundial de la Salud clasificara la COVID-19 como pandemia en marzo de 2020, es decir, entre 2018 y 2022. Se elaboraron modelos para examinar dos resultados principales: (i) el numero total semanal de protestas del personal sanitario en todo el mundo; y (ii) el numero de paises con una o mas protestas del personal sanitario en una semana determinada. Resultados En total, hubo 18 322 protestas de personal sanitario en 133 paises entre 2018 y 2022. El numero de protestas semanales del personal sanitario en todo el mundo aumento un 47% (30,1/63,5), lo que supone un aumento de 30,1 protestas por semana (intervalo de confianza del 95%, IC: 11,7-48,6) al inicio de la pandemia de la COVID-19. Ademas, el numero de paises que experimentaron este tipo de protestas en una semana determinada aumento un 24% (5,7/24,1) tras la declaracion de la pandemia (un aumento de 5,7 paises; IC del 95%: 3,5-7,8). Conclusion La pandemia aumento el nivel general de protestas del personal sanitario en todo el mundo, asi como el numero de paises que las experimentaron. Estas protestas ponen de manifiesto el descontento del personal sanitario. Dada la actual crisis mundial del personal sanitario, comprender y abordar los factores que impulsan el descontento del personal sanitario es importante para la politica y la seguridad sanitarias a nivel mundial., Introduction Protests, that is organized public demonstrations of grievances, by health workers have gained increasing attention in recent years. Health workforce crises are occurring around the world in both high- [...]

Published
2024
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5. Positive mass and Dirac operators on weighted manifolds and smooth metric measure spaces

Author

Law, Michael B., Lopez, Isaac M., and Santiago, Daniel

Subjects
Mathematics - Differential Geometry, Mathematical Physics
Abstract

We establish a weighted positive mass theorem which unifies and generalizes results of Baldauf--Ozuch and Chu--Zhu. Our result is in fact equivalent to the usual positive mass theorem, and can be regarded as a positive mass theorem for smooth metric measure spaces. We also study Dirac operators on certain warped product manifolds associated to smooth metric measure spaces. Applications of this include, among others, an alternative proof for a special case of our positive mass theorem, eigenvalue bounds for the Dirac operator on closed spin manifolds, and a new way to understand the weighted Dirac operator using warped products., Comment: 19 pages; references added, edited for readability

Published
2023

6. Distributional Robustness and Transfer Learning Through Empirical Bayes

Author

Law, Michael, Bühlmann, Peter, and Ritov, Ya'acov

Subjects
Mathematics - Statistics Theory
Abstract

We consider the problem of statistical inference on parameters of a target population when auxiliary observations are available from related populations. We propose a flexible empirical Bayes approach that can be applied on top of any asymptotically linear estimator to incorporate information from related populations when constructing confidence regions. The proposed methodology is valid regardless of whether there are direct observations on the population of interest. We demonstrate the performance of the empirical Bayes confidence regions on synthetic data as well as on the Trends in International Mathematics and Sciences Study when using the debiased Lasso as the basic algorithm in high-dimensional regression.

Published
2023

7. Barriers and facilitators to healthcare facility utilization by non-Ebola patients during the 2018–2020 Ebola outbreak in the Democratic Republic of Congo

Author

Kyomba, Gabriel Kalombe, Law, Michael Robert, Grépin, Karen Ann, Mayaka, Serge Manitu, Mambu, Thérèse Nyangi-Mondo, Mbunga, Branly Kilola, Hategeka, Celestin, Mapatano, Mala Ali, Konde, Joël Nkiama-Numbi, Ngo-Bebe, Dosithée, Babakazo, Pélagie Diambalula, Mafuta, Eric Musalu, and Kiyombo, Guillaume Mbela

Published
2024
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8. Invariant Probabilistic Prediction

Author

Henzi, Alexander, Shen, Xinwei, Law, Michael, and Bühlmann, Peter

Subjects
Statistics - Methodology, Computer Science - Machine Learning, Statistics - Machine Learning
Abstract

In recent years, there has been a growing interest in statistical methods that exhibit robust performance under distribution changes between training and test data. While most of the related research focuses on point predictions with the squared error loss, this article turns the focus towards probabilistic predictions, which aim to comprehensively quantify the uncertainty of an outcome variable given covariates. Within a causality-inspired framework, we investigate the invariance and robustness of probabilistic predictions with respect to proper scoring rules. We show that arbitrary distribution shifts do not, in general, admit invariant and robust probabilistic predictions, in contrast to the setting of point prediction. We illustrate how to choose evaluation metrics and restrict the class of distribution shifts to allow for identifiability and invariance in the prototypical Gaussian heteroscedastic linear model. Motivated by these findings, we propose a method to yield invariant probabilistic predictions, called IPP, and study the consistency of the underlying parameters. Finally, we demonstrate the empirical performance of our proposed procedure on simulated as well as on single-cell data.

Published
2023

9. Longitudinal Position and Cancer Risk in the United States Revisited

Author

Niu, Jin, Brown, Charlotte, Law, Michael, Colacino, Justin, and Ritov}, Ya'acov

Subjects
Statistics - Applications
Abstract

The debate over whether to keep daylight savings time has gained attention in recent years, with interest in understanding how the length of exposure to sunlight may affect health outcomes. In this study, we analyzed cancer incidence rates in counties located in different longitudinal positions within time zones and across time zone borders in the contiguous United States. Using both linear and spatial regression models, we found that differences in cancer rates are not significant within time zones or near time zone borders, which challenges previous research. Furthermore, we examined breast, liver, lung, and prostate cancer rates and found that only breast and liver cancers show an increase in incidence from the eastern border to the west within a time zone, while prostate cancer shows the opposite trend. Our study provides insights into the potential difference on human health incurred by an additional hour of sunlight in the morning versus in the evening, which could inform the ongoing discussions about daylight savings time.

Published
2023

10. A Rank-Based Sequential Test of Independence

Author

Henzi, Alexander and Law, Michael

Subjects
Statistics - Methodology
Abstract

We consider the problem of independence testing for two univariate random variables in a sequential setting. By leveraging recent developments on safe, anytime-valid inference, we propose a test with time-uniform type I error control and derive explicit bounds on the finite sample performance of the test. We demonstrate the empirical performance of the procedure in comparison to existing sequential and non-sequential independence tests. Furthermore, since the proposed test is distribution free under the null hypothesis, we empirically simulate the gap due to Ville's inequality, the supermartingale analogue of Markov's inequality, that is commonly applied to control type I error in anytime-valid inference, and apply this to construct a truncated sequential test.

Published
2023

11. Large-scale detector testing for the GAPS Si(Li) Tracker

Author

Xiao, Mengjiao, Stoessl, Achim, Roach, Brandon, Gerrity, Cory, Bouche, Ian, Bridges, Gabriel, von Doetinchem, Philip, Hailey, Charles J., Kraych, Derik, Katt, Anika, Law, Michael, Lowell, Alexander, Martinez, Evan, Perez, Kerstin, Reed, Maggie, Rodriguez, Chelsea, Saffold, Nathan, Stringfield, Ceaser, Weiner, Hershel, and Yee, Kelsey

Subjects
Physics - Instrumentation and Detectors, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

Lithium-drifted silicon [Si(Li)] has been used for decades as an ionizing radiation detector in nuclear, particle, and astrophysical experiments, though such detectors have frequently been limited to small sizes (few cm$^2$) and cryogenic operating temperatures. The 10-cm-diameter Si(Li) detectors developed for the General Antiparticle Spectrometer (GAPS) balloon-borne dark matter experiment are novel particularly for their requirements of low cost, large sensitive area (~10 m$^2$ for the full 1440-detector array), high temperatures (near -40$\,^\circ$C), and energy resolution below 4 keV FWHM for 20--100-keV x-rays. Previous works have discussed the manufacturing, passivation, and small-scale testing of prototype GAPS Si(Li) detectors. Here we show for the first time the results from detailed characterization of over 1100 flight detectors, illustrating the consistent intrinsic low-noise performance of a large sample of GAPS detectors. This work demonstrates the feasibility of large-area and low-cost Si(Li) detector arrays for next-generation astrophysics and nuclear physics applications., Comment: Updated to version accepted in IEEE Trans Nucl Sci. Minor changes to text, fixed plotting error on Fig. 5. Conclusions unchanged

Published
2023
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12. Rank-Constrained Least-Squares: Prediction and Inference

Author

Law, Michael, Ritov, Ya'acov, Zhang, Ruixiang, and Zhu, Ziwei

Subjects
Mathematics - Statistics Theory
Abstract

In this work, we focus on the high-dimensional trace regression model with a low-rank coefficient matrix. We establish a nearly optimal in-sample prediction risk bound for the rank-constrained least-squares estimator under no assumptions on the design matrix. Lying at the heart of the proof is a covering number bound for the family of projection operators corresponding to the subspaces spanned by the design. By leveraging this complexity result, we perform a power analysis for a permutation test on the existence of a low-rank signal under the high-dimensional trace regression model. We show that the permutation test based on the rank-constrained least-squares estimator achieves non-trivial power with no assumptions on the minimum (restricted) eigenvalue of the covariance matrix of the design. Finally, we use alternating minimization to approximately solve the rank-constrained least-squares problem to evaluate its empirical in-sample prediction risk and power of the resulting permutation test in our numerical study.

Published
2021

13. High-Dimensional Varying Coefficient Models with Functional Random Effects

Author

Law, Michael and Ritov, Ya'acov

Subjects
Mathematics - Statistics Theory
Abstract

We consider a sparse high-dimensional varying coefficients model with random effects, a flexible linear model allowing covariates and coefficients to have a functional dependence with time. For each individual, we observe discretely sampled responses and covariates as a function of time as well as time invariant covariates. Under sampling times that are either fixed and common or random and independent amongst individuals, we propose a projection procedure for the empirical estimation of all varying coefficients. We extend this estimator to construct confidence bands for a fixed number of varying coefficients.

Published
2021

17. The Hot Hand and Its Effect on the NBA

Author

McNair, Brian, Margolin, Eric, Law, Michael, and Ritov, Ya'acov

Subjects
Statistics - Applications
Abstract

This paper aims to revisit and expand upon previous work on the "hot hand" phenomenon in basketball, specifically in the NBA. Using larger, modern data sets, we test streakiness of shooting patterns and the presence of hot hand behavior in free throw shooting, while going further by examining league-wide hot hand trends and the changes in individual player behavior. Additionally, we perform simulations in order to assess their power. While we find no evidence of the hot hand in game-play and only weak evidence in free throw trials, we find that some NBA players exhibit behavioral changes based on the outcome of their previous shot.

Published
2020

18. Benzodiazepine-Free Cardiac Anesthesia for Reduction of Postoperative Delirium (B-Free): A Protocol for a Multi-centre Randomized Cluster Crossover Trial

Author

Spence, Jessica, Belley-Côté, Emilie, Jacobsohn, Eric, Lee, Shun Fu, D’Aragon, Frederick, Avidan, Michael, Mazer, C. David, Rousseau-Saine, Nicolas, Rajamohan, Raja, Pryor, Kane, Klein, Rael, Tan, Edmund (Chong-How), Cameron, Matthew, Di Sante, Emily, DeBorba, Erin, Mustard, Mary, Couture, Etienne, Zamper, Raffael, Law, Michael, Djaiani, George, Saha, Tarit, Choi, Stephen, Hedlin, Peter, Pikaluk, Ryan, Lam, Wing Ying, Deschamps, Alain, Whitlock, Richard, Dulong, Braden, Devereaux, P.J., Beaver, Chris, Kloppenburg, Shelley, Oczkowski, Simon, McIntyre, William Finlay, McFarling, Matthew, Lamy, Andre, Vincent, Jessica, and Connolly, Stuart

Published
2023
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20. Estimating the Random Effect in Big Data Mixed Models

Author

Law, Michael and Ritov, Ya'acov

Subjects
Mathematics - Statistics Theory, Statistics - Methodology
Abstract

We consider three problems in high-dimensional Gaussian linear mixed models. Without any assumptions on the design for the fixed effects, we construct an asymptotic $F$-statistic for testing whether a collection of random effects is zero, derive an asymptotic confidence interval for a single random effect at the parametric rate $\sqrt{n}$, and propose an empirical Bayes estimator for a part of the mean vector in ANOVA type models that performs asymptotically as well as the oracle Bayes estimator. We support our results with numerical simulations and provide comparisons with oracle estimators. The procedures developed are applied to the Trends in International Mathematics and Sciences Study (TIMSS) data.

Published
2019

21. Inference Without Compatibility

Author

Law, Michael and Ritov, Ya'acov

Subjects
Mathematics - Statistics Theory
Abstract

We consider hypotheses testing problems for three parameters in high-dimensional linear models with minimal sparsity assumptions of their type but without any compatibility conditions. Under this framework, we construct the first $\sqrt{n}$-consistent estimators for low-dimensional coefficients, the signal strength, and the noise level. We support our results using numerical simulations and provide comparisons with other estimators.

Published
2019

22. The effect of changing screening practices and demographics on the incidence of gestational diabetes in British Columbia, 2005-2019

Author

Nethery, Elizabeth, Law, Michael R., Kotaska, Andrew, Janssen, Patricia A., and Hutcheon, Jennifer A.

Subjects
Diabetes in pregnancy -- Diagnosis -- Care and treatment, Medical screening -- Methods -- Evaluation, Health
Abstract

Background: Rates of gestational diabetes are reported to be increasing in many jurisdictions, but the reasons for this are poorly understood. We sought to evaluate the relative contribution of screening practices for gestational diabetes (including completion and methods of screening) and population characteristics to risk of gestational diabetes in British Columbia, Canada, from 2005 to 2019. Methods: We used a population-based cohort from a provincial registry of perinatal data, linked to laboratory billing records. We used data on screening completion, screening method (1-step 75-g glucose test or 2-step approach of 50-g glucose screening test, followed by a diagnostic test for patients who screen positive) and demographic risk factors. We modelled predicted annual risk for gestational diabetes, sequentially adjusted for screening completion, screening method and risk factors. Results: We included 551 457 pregnancies in the study cohort. The incidence of gestational diabetes more than doubled over the study period, from 7.2% in 2005 to 14.7% in 2019. Screening completion increased from 87.2% in 2005 to 95.5% in 2019. Use of 1-step screening methods increased from 0.0% in 2005 to 39.5% in 2019 among those who were screened. Unadjusted models estimated a 2.04 (95% confidence interval [CI] 1.94-2.13) increased risk of gestational diabetes in 2019 (v. 2005). This increase was 1.89 (95% CI 1.81-1.98) after accounting for the rise in screening completion and 1.34 (95% CI 1.28-1.40) after accounting for changes in screening methods. Further accounting for demographic risk factors (e.g., age, body mass index, prenatal care) had a small impact (increase of 1.25, 95% CI 1.19-1.31). Interpretation: Most of the observed increase in the incidence of gestational diabetes was attributable to changes in screening practices (primarily changes in screening methods) rather than changing population factors. Our findings highlight the importance of understanding variation in screening practices when monitoring incidence rates for gestational diabetes., Rates of gestational diabetes are reported to be increasing worldwide. (1) In Canada, the rate of gestational diabetes increased from 4.0% of deliveries in 2004 to 7.0% in 2014. (2) [...]

Published
2023
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25. Childhood immunization during the COVID-19 pandemic: experiences in Haiti, Lesotho, Liberia and Malawi/Immunisation infantile durant la pandemie de COVID-19: experiences en Haiti, au Lesotho, au Liberia et au Malawi/Inmunizacion infantil durante la pandemia de la COVID-19: experiencias en Haiti, Lesotho, Liberia y Malawi

Author

Connolly, Emilia, Boley, Emma J., Fejfar, Donald Luke, Varney, Prince F., Aron, Moses B., Fulcher, Isabel R., Lambert, Wesler, Ndayizigiye, Melino, Law, Michael R., Mugunga, Jean-Claude, and Hedt- Gauthier, Bethany

Subjects
Epidemics -- Liberia -- Malawi -- Lesotho -- Haiti, Vaccination -- Comparative analysis, Coronaviruses -- Comparative analysis, Management information systems -- Comparative analysis, MIS, Health, World Health Organization
Abstract

Objective To examine changes in vaccination of children younger than 1 year during the coronavirus disease 2019 (COVID-19) pandemic (March 2020-August 2021) in Haiti, Lesotho, Liberia and Malawi. Methods We used data from health management information systems on vaccination of children aged 12 months or younger in districts supported by Partners In Health. We used data from January 2016 to February 2020 and a linear model with negative binomial distribution to estimate the expected immunization counts for March 2020-August 2021 with 95% prediction intervals, assuming no pandemic. We compared these expected levels with observed values and estimated the immunization deficits or excesses during the pandemic months. Findings Baseline vaccination counts varied substantially by country, with Lesotho having the lowest count and Haiti the highest. We observed declines in vaccination administration early in the COVID-19 pandemic in Haiti, Lesotho and Liberia. Continued declines largely corresponded to high rates of COVID-19 infection and discrete stock-outs. By August 2021, vaccination levels had returned to close to or above expected levels in Haiti, Liberia and Lesotho; in Malawi levels remained below expected. Conclusion Patterns of childhood immunization coverage varied by country over the course of the pandemic, with significantly lower than expected vaccination levels seen in one country during subsequent COVID-19 waves. Governments and health-care stakeholders should monitor vaccine coverage closely and consider interventions, such as community outreach, to avoid or combat the disruptions in childhood vaccination. Objectif Etudier les changements en matiere de vaccination des enfants ages de moins d'un an durant la pandemie de maladie a coronavirus 2019 (COVID-19) en Haiti, au Lesotho, au Liberia et au Malawi, entre mars 2020 et aout 2021. Methodes Nous avons utilise les donnees issues des systemes d'information pour la gestion de la sante et portant sur la vaccination des enfants de moins de 12 mois, dans les districts soutenus par l'association Partners In Health. Nous nous sommes appuyes sur des donnees collectees entre janvier 2016 et fevrier 2020, ainsi que sur un modele lineaire avec distribution binomiale negative, afin d'estimer les chiffres d'immunisation attendus pour la periode allant de mars 2020 a aout 2021 en appliquant des intervalles de prevision de 95%, en supposant qu'il n'y ait pas eu de pandemie. Enfin, nous avons compare ces previsions avec les valeurs observees, puis calcule les excedents ou deficits en la matiere pendant les mois de pandemie. Resultats Les chiffres de vaccination initiaux etaient tres differents d'un pays a l'autre, le Lesotho enregistrant le plus faible taux et Haiti, le plus eleve. Nous avons constate une diminution de l'administration des vaccins au debut de la pandemie de COVID-19 en Haiti, au Lesotho et au Liberia. Les baisses continues correspondaient a des niveaux eleves d'infection a la COVID-19 et a des ruptures de stock distinctes. En aout 2021, les taux de vaccination avaient repris un cours normal ou superieur a la norme en Haiti, au Liberia et au Lesotho; au Malawi, ils sont restes inferieurs aux resultats escomptes. Conclusion Les schemas de couverture vaccinale infantile ont varie en fonction des pays tout au long de la pandemie, avec des taux de vaccination nettement inferieurs aux previsions dans l'un des pays durant les vagues successives de COVID-19. Les gouvernements et acteurs du secteur de la sante devraient surveiller attentivement la couverture vaccinale et envisager des interventions telles que la sensibilisation communautaire s'ils souhaitent eviter ou mettre fin aux interruptions dans la vaccination des enfants. Objetivo Analizar los cambios en la vacunacion de los ninos menores de 1 ano durante la pandemia de la coronavirosis de 2019 (COVID-19) (entre marzo de 2020 y agosto de 2021) en Haiti, Lesotho, Liberia y Malawi. Metodos Se emplearon datos de los sistemas de informacion de gestion sanitaria sobre la vacunacion de ninos de 12 meses o menos en los distritos que reciben apoyo de Partners In Health. Se usaron datos de enero de 2016 a febrero de 2020 y un modelo lineal con distribucion binomial negativa para estimar las cifras de inmunizacion esperadas para el periodo de marzo de 2020 a agosto de 2021 con intervalos de prediccion del 95 %, suponiendo que no hay pandemia. Se compararon estos niveles esperados con los valores observados y se estimaron los deficits o excesos de inmunizacion durante los meses de la pandemia. Resultados El numero de vacunas de referencia vario bastante segun el pais, siendo Lesotho el que tuvo el numero mas bajo y Haiti el mas alto. Se observo una disminucion en la administracion de vacunas al principio de la pandemia de la COVID-19 en Haiti, Lesotho y Liberia. Las disminuciones continuas fueron en gran medida consecuencia de las altas tasas de infeccion por la COVID-19 y a la escasez de existencias. En agosto de 2021, los niveles de vacunacion se habian acercado o superado los niveles esperados en Haiti, Liberia y Lesotho; en Malawi los niveles seguian siendo inferiores a los esperados. Conclusion Los patrones de cobertura de la inmunizacion infantil variaron segun el pais en el transcurso de la pandemia, con niveles de vacunacion mucho mas bajos de lo esperado en un pais durante las siguientes oleadas de la COVID-19. Los gobiernos y las partes interesadas en la atencion sanitaria deben supervisar de cerca la cobertura de la vacunacion y contemplar intervenciones, como la divulgacion en la comunidad, para evitar o superar las interrupciones de la vacunacion infantil., Introduction The coronavirus disease 2019 (COVID-19) pandemic has severely affected health services globally, leading to concerns about disruptions to essential services such as immunizations. (1) Vaccinations, particularly those given in [...]

Published
2022
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30. Adoption des medicaments biosimilaires au Canada : analyse des politiques provinciales et donnees sur leur utilisation

Author

McClean, Alison R., Law, Michael R., Harrison, Mark, Bansback, Nick, Gomes, Tara, and Tadrous, Mina

Subjects
Biosimilar pharmaceuticals -- Contracts -- Information management -- Analysis, Company systems management, Contract agreement, Health
Abstract

Les agents biologiques representent un segment important des depenses en medicaments au Canada : alors qu'ils ne constituaient que 1,5% du volume des ordonnances, les agents biologiques ont genere 27,3% [...]

Published
2022
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31. Uptake of biosimilar drugs in Canada: analysis of provincial policies and usage data

Author

McClean, Alison R., Law, Michael R., Harrison, Mark, Bansback, Nick, Gomes, Tara, and Tadrous, Mina

Subjects
Insulin glargine -- User statistics -- Laws, regulations and rules, Biosimilar pharmaceuticals -- User statistics -- Laws, regulations and rules, Monoclonal antibodies -- User statistics -- Laws, regulations and rules, Pharmaceutical policy -- Analysis, Provinces -- Statistics -- Health aspects, Government regulation, Health
Abstract

Biologics represent a large segment of drug spending in Canada: although they constituted just 1.5% of prescription volumes, biologics accounted for 27.3% of expenditures in 2018. (1) As of 2018, [...]

Published
2022
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32. The effect of coronary revascularization treatment timing on mortality in patients with stable ischemic heart disease in British Columbia.

Author

Hardiman, Sean, Fradet, Guy, Kuramoto, Lisa, Law, Michael, Robinson, Simon, and Sobolev, Boris

Subjects
CORONARY artery bypass, MAXILLOFACIAL surgery, MYOCARDIAL ischemia, CORONARY disease, PERCUTANEOUS coronary intervention
Abstract

Background: Prior research has shown that patients with stable ischemic heart disease who undergo delayed coronary artery bypass graft (CABG) surgery face higher mortality rates than those who receive CABG within the time recommended by physicians. However, this research did not account for percutaneous coronary intervention (PCI), a widely available alternative to delayed CABG in many settings. We sought to establish whether there was a difference in mortality between timely PCI and delayed CABG. Methods: We identified 25,520 patients 60 years or older who underwent first-time non-emergency revascularization for angiographically-proven, stable left main or multi-vessel ischemic heart disease in British Columbia between January 1, 2001, and December 31, 2016. We estimated unadjusted and adjusted mortality after index revascularization or last staged PCI for patients undergoing delayed CABG compared to timely PCI. Findings: After adjustment with inverse probability of treatment weights, at three years, patients who underwent delayed CABG had a statistically significant lower mortality compared with patients who received timely PCI (4.3% delayed CABG, 13.5% timely PCI; risk ratio 0.32, 95% CI 0.24–0.40). Interpretation: Patients who undergo CABG with delay have a lower risk of death than patients who undergo PCI within appropriate time. Our results suggest that patients who wish to receive CABG as their revascularization treatment will receive a mortality benefit over PCI as an alternative strategy. [ABSTRACT FROM AUTHOR]

Published
2024
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33. Building Capacity for COVID-19 Surveillance: A Statistics Course for Health Officials in Seven Low- and Middle-Income Countries.

Author

Fulcher, Isabel R., Fejfar, Donald, Kulikowski, Nichole, Mugunga, Jean-Claude, Law, Michael, and Hedt-Gauthier, Bethany

Subjects
PUBLIC health officers, MIDDLE-income countries, COVID-19 pandemic, MEDICAL statistics, COVID-19
Abstract

During the COVID-19 pandemic, a group of health program implementors and research analysts across seven low- and middle-income countries (LMICs) alongside Boston-based collaborators convened to implement data-driven approaches for public health response. An intensive statistics and data science training short course was developed to ensure that in-country researchers could implement the necessary statistical methods for COVID-19 surveillance. The main goal of the course was to enable interpretation of findings from time series analyses and flag potential data issues. This manuscript summarizes our experience teaching this course, including a detailed course overview, participant feedback, and thoughts on how targeted, online courses can be used to support statistical capacity building in LMICs. [ABSTRACT FROM AUTHOR]

Published
2024
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39. Policy changes and physicians opting out from Medicare in Quebec: an interrupted time-series analysis

Author

Contandriopoulos, Damien and Law, Michael R.

Subjects
Medicare -- Laws, regulations and rules -- Usage, Medical fees -- Forecasts and trends, Physicians (General practice) -- Beliefs, opinions and attitudes -- Statistics, Government regulation, Market trend/market analysis, Health, Chaoulli v. Quebec Attorney General 2005 S.C.C. 35 (Can.)
Abstract

BACKGROUND: In all Canadian provinces, physicians can decide to either bill the provincial public system (opt in) or work privately and bill patients directly (opt out). We hypothesized that 2 policy events were associated with an increase in physicians opting out in Quebec. METHODS: The 2 policy events of interest were the 2005 Supreme Court of Canada ruling on Chaoulli v. Quebec and a regulatory clampdown forbidding double billing that was implemented by Quebec's government in 2017. We used interrupted time-series analyses of the Quebec government's yearly list of physicians who chose to opt out from 1994 to 2019 to analyze the relation between these events and physician billing status. RESULTS: The number of family physicians who opted out increased from 9 in 1994 to 347 in 2019. Opting out increased after the Chaoulli ruling, and our analysis suggested that between 2005 and 2019, 284 more family physicians opted out than if pre-Chaoulli trends had continued. The number of specialist physicians who opted out rose from 23 in 1994 to 150 in 2019. Our analysis suggested that an additional 69 specialist physicians opted out after the 2017 clampdown on double billing than previous trends would have predicted. INTERPRETATION: We found that the number of physicians who opted out increased in Quebec, and increases after 2 policy actions suggest an association with these policy interventions. Opting out decisions are likely important inputs into decision-making by physicians, which, in turn may influence the provision of publicly funded health care., In all Canadian provinces, most physicians work as part of a private business. Whether they are solo practitioners or part of larger group practices, physicians can bill the provincial public [...]

Published
2021
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41. Understanding the factors related to how East and Southeast Asian immigrant youth and families access mental health and substance use services: A scoping review.

Author

Gao, Chloe, Cho, Lianne L., Dhillon, Avneet, Kim, Soyeon, McGrail, Kimberlyn, Law, Michael R., Sunderji, Nadiya, and Barbic, Skye

Subjects
SOUTHEAST Asians, IMMIGRANT children, ECOLOGICAL systems theory, IMMIGRANT families
Abstract

The objective of the review is to identify factors related to how East and Southeast Asian immigrant youth aged 12–24 and their families access mental health and substance use (MHSU) services. To address how East and Southeast Asian youth and their families access mental health and substance use services, a scoping review was conducted to identify studies in these databases: PubMed, MEDLINE (Ovid), EMBASE (Ovid), PsychINFO, CINAHL, and Sociology Collection. Qualitative content analysis was used to deductively identify themes and was guided by Bronfenbrenner's Ecological Systems Theory, the process-person-context-time (PPCT) model, and the five dimensions of care accessibility (approachability, acceptability, availability and accommodation, appropriateness, affordability). Seventy-three studies met the inclusion criteria. The dimensions of healthcare accessibility shaped the following themes: 1) Acceptability; 2) Appropriateness; 3) Approachability; 4) Availability and Accommodation. Bronfenbrenner's Ecological Systems Theory and the PPCT model informed the development of the following themes: 1) Immediate Environment/Proximal Processes (Familial Factors, Relationships with Peers; 2) Context (School-Based Services/Community Resources, Discrimination, Prevention, Virtual Care); 3) Person (Engagement in Services/Treatment/Research, Self-management); 4) Time (Immigration Status). The study suggests that there is a growing body of research (21 studies) focused on identifying acceptability factors, including Asian cultural values and the model minority stereotype impacting how East and Southeast Asian immigrant youth access MHSU services. This review also highlighted familial factors (16 studies), including family conflict, lack of MHSU literacy, reliance on family as support, and family-based interventions, as factors affecting how East and Southeast Asian immigrant youth access MHSU care. However, the study also highlighted a dearth of research examining how East and Southeast Asian youth with diverse identities access MHSU services. This review emphasizes the factors related to the access to MHSU services by East and Southeast Asian immigrant youth and families while providing insights that will improve cultural safety. [ABSTRACT FROM AUTHOR]

Published
2024
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42. Validating methods used to identify non‐adherence adverse drug events in Canadian administrative health data.

Author

Wickham, Maeve E., McGrail, Kimberlyn M., Law, Michael R., Cragg, Amber, and Hohl, Corinne M.

Subjects
PATIENT compliance, MEDICAL personnel, CHRONIC diseases, DRUG analysis
Abstract

Aims: Medication non‐adherence is a type of adverse drug event that can lead to untreated and exacerbated chronic illness, and that drives healthcare utilization. Research using medication claims data has attempted to identify instances of medication non‐adherence using the proportion of days covered or by examining gaps between medication refills. We sought to validate these measures compared to a gold standard diagnosis of non‐adherence made in hospital. Methods: This was a retrospective analysis of adverse drug events diagnosed during three prospective cohorts in British Columbia between 2008 and 2015 (n = 976). We linked prospectively identified adverse drug events to medication claims data to examine the sensitivity and specificity of typical non‐adherence measures. Results: The sensitivity of the non‐adherence measures ranged from 22.4% to 37.5%, with a proportion of days covered threshold of 95% performing the best; the non‐persistence measures had sensitivities ranging from 10.4% to 58.3%. While a 7‐day gap was most sensitive, it classified 61.2% of the sample as non‐adherent, whereas only 19.6% were diagnosed as such in hospital. Conclusions: The methods used to identify non‐adherence in administrative databases are not accurate when compared to a gold standard diagnosis by healthcare providers. Research that has relied on administrative data to identify non‐adherent patients both underestimates the magnitude of the problem and may label patients as non‐adherent who were in fact adherent. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Trends in Providing Out-of-Office, Urgent After-Hours, and On-Call Care in British Columbia

Author

Hedden, Lindsay, Lavergne, M. Ruth, McGrail, Kimberlyn M., Law, Michael R., Bourgeault, Ivy L., McCracken, Rita, and Barer, Morris L.

Subjects
Medical care utilization -- Forecasts and trends -- Methods, Work hours -- Forecasts and trends -- Methods, Primary health care -- Methods -- Forecasts and trends, Market trend/market analysis, Health, Science and technology
Abstract

PURPOSE Providing care in alternative (non-office) locations and outside office hours are important elements of access and comprehensiveness of primary care. We examined the trends in and determinants of the services provided in a cohort of primary care physicians in British Columbia, Canada. METHODS We used physician-level payments for all primary care physicians practicing in British Columbia from 2006-2007 through 2011-2012. We examined the association between physician demographics and practice characteristics and payment for care in alternative locations and after hours across rural, urban, and metropolitan areas using longitudinal mixed-effects models. RESULTS The proportion of physicians who provided care in alternative locations and after hours declined significantly during the period, in rural, urban, and metropolitan practices. Declines ranged from 5% for long-term care facility visits to 22% for after-hours care. Female physicians, and those in the oldest age category, had lower odds of providing care at alternative locations and for urgent after-hours care. Compared with those practicing in metropolitan centers, physicians working in rural areas had significantly higher odds of providing care both in alternative locations and after hours. CONCLUSION Care provided in non-office locations and after office hours declined significantly during the study period. Jurisdictions where providing these services are not mandated, and where similar workforce demographic shifts are occurring, may experience similar accessibility challenges. Key words: primary health care; physicians; primary care; after-hours care; British Columbia; cohort studies, INTRODUCTION Achieving high quality and patient-centered care requires health care system structures that support physician service delivery outside regular office hours and away from regular office locations. For example, when [...]

Published
2019
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47. Developing Electronic Performance Support Systems for Professionals.

Author

Law, Michael P.

Abstract

This paper discusses a variety of development strategies and issues involved in the development of electronic performance support systems (EPSS) for professionals. The topics of front-end analysis, development, and evaluation are explored in the context of a case study involving the development of an EPSS to support teachers in the use of alternative assessments. Strategies and concepts such as rapid prototyping, formative experimentation, usability, and socio-technical perspectives are highlighted. EPSS developers utilize principles found in instructional systems, software engineering, performance technology, and formative experimentation to develop an effective system for teachers. By making usability a goal and focusing on the social, organizational, and cultural factors that influence how work is performed by professionals in a specific work context, developers increase the likelihood of developing effective EPSSs that support the people and organization in meeting their goals. A figure illustrates the system prototype. (Contains 20 references.) (Author/MAS)

Published
1995

49. Effect of a Billing Code to Reimburse Nurse‐SupportedRheumatology Care on Health Care Costs and Access: An Interrupted Time Series Analysis

Author

Trenaman, Logan, Guh, Daphne, Law, Michael R., Cheng, Lucy, and Harrison, Mark

Abstract

This study was undertaken to evaluate the impact of a Multidisciplinary Care Assessment (MCA) billing code on health system costs and access to care in British Columbia (BC). Data on all people treated by rheumatologists in BC were obtained from five linked health administrative databases held by Population Data BC from April 1, 2006, to March 31, 2020. Rheumatologists were allocated to either the intervention (ever‐billers) or control groups (never‐billers). For the intervention group, the index date was the month of the first MCA code billing. For the control group the index dates were imputed from intervention index dates. Our analysis focused on a 48‐month period (24 months before and after the index date). We evaluated the impact on two cost (costs related to rheumatoid arthritis [RA]; total health care costs) and access outcomes (rheumatology‐related visits per rheumatologist; days between rheumatology visits for patients with RA) using an interrupted time series analysis. A total of 46 rheumatologists (31 intervention and 15 control) met our inclusion criteria. Introduction of the MCA was associated with a small but significant increase in RA‐related costs that, at 2 years, translates to a net absolute change of $9.66 per patient per month, but no statistically significant changes in total health care costs. There was no statistically significant change in the number of rheumatology‐related visits, but at 2 years there was a net absolute reduction in the median days between rheumatologist visits for patients with RA (6.3 days). The introduction of the MCA code was associated with a negligible increase in the RA‐related costs and an improvement in access to ongoing care for patients.

Published
2024
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