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Background: Risk ratio is a popular effect measure in epidemiological research. Although previous research has suggested that logistic regression may provide biased odds ratio estimates when the number of events is small and there are multiple confounders, the performance of risk ratio estimation has yet to be examined in the presence of multiple confounders. Methods: We conducted a simulation study to evaluate the statistical performance of three regression approaches for estimating risk ratios: (1) risk ratio interpretation of logistic regression coefficients, (2) modified Poisson regression, and (3) regression standardization using logistic regression. We simulated 270 scenarios with systematically varied sample size, the number of binary confounders, exposure proportion, risk ratio, and outcome proportion. Performance evaluation was based on convergence proportion, bias, standard error estimation, and confidence interval coverage. Results: With a sample size of 2500 and an outcome proportion of 1%, both logistic regression and modified Poisson regression at times failed to converge, and the three approaches were comparably biased. As the outcome proportion or sample size increased, modified Poisson regression and regression standardization yielded unbiased risk ratio estimates with appropriate confidence intervals irrespective of the number of confounders. The risk ratio interpretation of logistic regression coefficients, by contrast, became substantially biased as the outcome proportion increased. Conclusions: Regression approaches for estimating risk ratios should be cautiously used when the number of events is small. With an adequate number of events, risk ratios are validly estimated by modified Poisson regression and regression standardization, irrespective of the number of confounders. [ABSTRACT FROM AUTHOR]

Purpose: Non-inferiority for overall survival (OS) following alternate-day treatment with the oral anticancer drug S-1 compared with standard daily treatment was assessed in Japanese patients with unresectable advanced pancreatic cancer in a multicenter, randomized, phase II study. This trial was registered at the UMIN Clinical Trials Registry (no. 000008604).Methods: Chemotherapy-naïve patients with locally advanced or metastatic pancreatic cancer were randomly assigned 2:1 to treatment with alternate-day (twice daily on alternate days from days 1 through 42 of a 42-day cycle) or daily (twice daily on days 1 through 28 of a 42-day cycle) treatment with S-1. The primary endpoint was OS. Secondary endpoints were progression-free survival (PFS), time to treatment failure, response rate, quality of life assessments, and safety.Results: A total of 190 patients were enrolled, of which 185 were included in the final analysis (alternate-day: 121; daily: 64). Median OS was 9.4 for the alternate-day group and 10.4 months for the daily group [hazard ratio (HR), 1.19; 95% credible interval, 0.86 to 1.64], indicating that non-inferiority of alternate-day treatment to daily treatment was not demonstrated. Median PFS was 3.0 for the alternate-day group and 4.2 months for the daily group (HR, 1.65; 95% credible interval, 1.20-2.29). The incidence of anorexia, fatigue, neutrophils, pigmentation, and pneumonitis was lower in alternate-day treatment compared with daily treatment.Conclusion: S-1 for advanced pancreatic cancer should be taken daily as recommended, based on the decreased OS and PFS and marginal improvement in safety observed in the alternate-day group. [ABSTRACT FROM AUTHOR]

We examined the association between intellectual disabilities (ID) and pneumonia severity at admission. We extracted patients admitted to hospital for pneumonia from July 2010 to March 2018 using the Diagnosis Procedure Combination database. We measured pneumonia severity using the A-DROP system. After 1:4 cohort matching between patients with and without ID, we conducted conditional logistic regression and mediation analyses. Of 1,141,158 patients, 531 had ID, and they had more severe pneumonia at admission (24.5% vs. 9.5%; P < 0.001). ID was significantly associated with severe pneumonia at admission (OR = 3.50; 95% CI: 2.68–4.58) and activities of daily living (ADL) mediated 73.8% (95% CI: 50.9%–105.0%) of the total association. Social barriers caused by reduced ADL may prevent patients with ID from accessing health care before their pneumonia becomes severe. Removing these barriers may decrease mortality from pneumonia among patients with ID by improving health care access. [ABSTRACT FROM AUTHOR]

Purpose: The development of new-onset atrial fibrillation (AF) in critically ill patients may be associated with poor outcomes. However, it is unknown whether sustained new-onset AF contributes to worse outcome. The aim of this study was to assess whether sustained new-onset AF is associated with stroke and death and to look for a possible dose-response relationship between AF duration and death.Methods: In a prospective cohort study conducted in 32 intensive care units in Japan from 2017 to 2018, we enrolled adult patients with new-onset AF. We compared patients with AF duration longer than 48 h with those with AF duration shorter than 48 h. To assess a dose-response relationship between AF duration and hospital mortality, we conducted landmark analysis and time-dependent Cox regression analysis.Results: Among a total of 423 new-onset AF patients, hospital mortality was 25%, and the incidence of in-hospital stroke was 4.6%. AF duration longer than 48 h was not independently associated with hospital mortality (adjusted odds ratio: 1.52; 95% Confidence Interval: 0.87-2.64). The incidence of in-hospital stroke was 7.6% in patients with AF duration longer than 48 h and 3.8% in those with AF duration shorter than 48 h (p = 0.154). When analyzing time more continuously, we observed a time-dependent association between AF duration and hospital mortality (p = 0.005 by landmark analysis and p = 0.019 by Cox analysis).Conclusions: Sustained new-onset AF was time-dependently associated with hospital mortality in ICU patients, albeit with some uncertainty since AF duration longer than 48 h was not independently associated with in-hospital death or stroke. [ABSTRACT FROM AUTHOR]