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316 results on '"Tavakoli, Hamid"'

1. Minding non-collapsibility of odds ratios when recalibrating risk prediction models

Author

Sadatsafavi, Mohsen, Tavakoli, Hamid, and Safari, Abdollah

Subjects
Statistics - Applications
Abstract

In clinical prediction modeling, model updating refers to the practice of modifying a prediction model before it is used in a new setting. In the context of logistic regression for a binary outcome, one of the simplest updating methods is a fixed odds-ratio transformation of predicted risks to improve calibration-in-the-large. Previous authors have proposed equations for calculating this odds-ratio based on the discrepancy between the prevalence in the original and the new population, or between the average of predicted and observed risks. We show that this method fails to consider the non-collapsibility of odds-ratio. Consequently, it under-corrects predicted risks, especially when predicted risks are more dispersed (i.e., for models with good discrimination). We suggest an approximate equation for recovering the conditional odds-ratio from the mean and variance of predicted risks. Brief simulations and a case study show that this approach reduces under-correction, sometimes substantially. R code for implementation is provided., Comment: 12 Pages, 1 Figure, 1567 words

Published
2021
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18. Risk and distribution of chronic obstructive pulmonary disease–related hospitalizations among primary care patients

Author

Garrison, Scott, Tavakoli, Hamid, Sadatsafavi, Mohsen, Korownyk, Christina S., Kolber, Michael R., and Allan, G. Michael

Subjects
Research
Abstract

OBJECTIVE: To determine the extent of chronic obstructive pulmonary disease (COPD) hospitalization in easily identifiable high-risk subgroups within a typical primary care practice. DESIGN: Prospective cohort analysis of administrative claims data. SETTING: British Columbia. PARTICIPANTS: British Columbia residents who were 50 years or older on December 31, 2014, and received a physician diagnosis of COPD between 1996 and 2014. MAIN OUTCOME MEASURES: Rate of acute exacerbation of COPD (AECOPD) or pneumonia hospitalization in 2015, broken down by risk identifiers including previous AECOPD admission, 2 or more community respirologist consultations, nursing home residence, or none of these. RESULTS: Of the 242,509 identified COPD patients (12.9% of British Columbia residents ≥50 years), 2.8% were hospitalized for AECOPD in 2015 (0.038 AECOPD hospitalizations per patient-year). The 12.0% with prior AECOPD hospitalization accounted for 57.7% of new AECOPD hospitalizations (0.183 hospitalizations per patient-year); the 7.7% with respirologist involvement accounted for 20.4% (0.102 hospitalizations per patient-year); and the 2.2% in nursing homes accounted for 3.6% (0.061 hospitalizations per patient-year). Those with any of the 3 risk identifiers accounted for only 1.5% more COPD hospitalizations (59.2%) than those with prior AECOPD hospitalization, suggesting prior AECOPD hospitalization is the most important indication of risk. A typical primary care practice held a median of 23 (interquartile range=4 to 65) COPD patients, of whom roughly 20 (86.4%) had none of these risk identifiers. This low-risk majority had only 0.018 AECOPD hospitalizations per patient-year. CONCLUSION: Most AECOPD hospitalizations occur in patients with previous such admissions. When time and resources are limited, COPD initiatives targeting primary care practices should focus more on the 2 to 3 patients with prior AECOPD hospitalization or more symptomatic disease, and less on the low-risk majority.

Published
2023

26. Antibiotic susceptibility patterns of isolated bacteria from bile fluids of patients with gallstone disease in Isfahan city (Iran)

Author

Fatemi Seyed-Masih, Doosti Abbas, Tavakoli Hamid, Moayednia Reza, Ghasemi-Dehkordi Payam, Kelidari Behrooz, Mahmudieh Mohsen, and Moayednia Milad

Subjects
Gallstones, extended-spectrum β-lactamases (ESBLs), disk diffusion test, molecular technique, Biology (General), QH301-705.5
Abstract

Bacterial infections are one of the important agents in the creation of gallstones in the gallbladder. In recent years the spread of antibiotic-resistant bacteria such as extended-spectrum β-lactamases (ESBL) is increasing and of concern in hospitalized patients worldwide. The purpose of this study was to investigate the antibiotic susceptibility patterns of isolated bacteria from the bile specimens of patients with chronic and acute cholecystitis who had been operated by single-incision laparoscopic cholecystectomy (SILC) in Isfahan (Iran) 2 using an antibiogram susceptibility test and molecular technique. The bile fluids of 91 patients were obtained from the Al-Zahra hospital and were cultured on specific media for the isolation of Gram-negative and positive bacteria and the disk diffusion test was done to determine the antibiotic susceptibility patterns of isolated bacteria. Finally, bacterial DNA was extracted from the bile samples and polymerase chain reaction (PCR) was performed to investigate extended-spectrum β-lactamases genes. The bacteria Escherichia coli, Klebsiella pneumoniae, Proteus spp. and Staphylococcus aureus were detected in bile specimens cultured with high frequency, and the results showed that biliary infection increased with aging in patients with gallstone disease operated by SILC. The results showed a high frequency of ESBL genes including TEM, SHV, and CTX-M in isolated bacteria (especially Escherichia coli and Klebsiella spp.). Thus, evaluating the antibiotic susceptibility patterns and screening of ESBLs bacteria in patients with gallstones are essential. Prescribing suitable drugs, designing good strategies, and informing the medical community could decrease bile infection and antibiotic-resistant bacteria in clinical centers and hospitals.

Published
2015
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36. Are COPD Prescription Patterns Aligned with Guidelines? Evidence from a Canadian Population-Based Study

Author

Bahremand,Taraneh, Etminan,Mahyar, Roshan-Moniri,Nardin, De Vera,Mary A, Tavakoli,Hamid, Sadatsafavi,Mohsen, Bahremand,Taraneh, Etminan,Mahyar, Roshan-Moniri,Nardin, De Vera,Mary A, Tavakoli,Hamid, and Sadatsafavi,Mohsen

Abstract

Taraneh Bahremand,1 Mahyar Etminan,2 Nardin Roshan-Moniri,1 Mary A De Vera,1 Hamid Tavakoli,1 Mohsen Sadatsafavi1 1Collaboration for Outcomes Research and Evaluation, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, BC, Canada; 2Department of Ophthalmology, Faculty of Medicine, The University of British Columbia, Vancouver, BC, CanadaCorrespondence: Mohsen SadatsafaviFaculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, CanadaEmail msafavi@mail.ubc.caBackground: In contemporary guidelines for the management of Chronic Obstructive Pulmonary Disease (COPD), the history of acute exacerbations plays an important role in the choice of long-term inhaled therapies. This study aimed at evaluating population-level trends of filled inhaled prescriptions over the time course of COPD and their relation to the history of exacerbations.Methods: We used administrative health databases in British Columbia, Canada (1997– 2015), to create a retrospective incident cohort of individuals with diagnosed COPD. We quantified long-acting inhaled medication prescriptions within each year of follow-up and documented their trend over the time course of COPD. Using generalized linear models, we investigated the association between the frequent exacerbator status (≥ 2 moderate or ≥ 1 severe exacerbation(s) in the previous 12 months) and filling a prescription after a physician visit.Results: 132,004 COPD patients were included (mean age 68.6, 49.2% female). The most common medication class during the first year of diagnosis was inhaled corticosteroids (ICS, used by 49.9%), followed by long-acting beta-2 adrenoreceptor agonists (LABA, 31.8%). Long-acting muscarinic receptor antagonists (LAMA) were the least commonly prescribed (10.4%). ICS remained the most common prescription throughout follow-up, being used by approximately 50% of patients during each year. 39.0% of patients received combination inhaled thera

Published
2021

44. Association between asthma control trajectories in preschoolers and disease remission

Author

Longo, Cristina, primary, Blais, Lucie, additional, Brownell, Marni, additional, Quail, Jacqueline M., additional, Sadatsafavi, Mohsen, additional, Forget, Amélie, additional, Turcot, Marc-André, additional, Nie, Yao, additional, Li, Wenbin, additional, Tavakoli, Hamid, additional, Tan, Qier, additional, Fan, Yuxin, additional, Platt, Robert W., additional, and Ducharme, Francine M., additional

Published
2020
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