Comparative effectiveness research includes cohort studies and registries of interventions. When investigators design such studies, how important is it to follow patients from the day they initiated treatment with the study interventions? Our article considers this question and related issues to start a dialogue on the value of the incident user design in comparative effectiveness research. By incident user design, we mean a study that sets the cohort's inception date according to patients' new use of an intervention. In contrast, most epidemiologic studies enroll patients who were currently or recently using an intervention when follow‐up began. We take the incident user design as a reasonable default strategy because it reduces biases that can impact non‐randomized studies, especially when investigators use healthcare databases. We review case studies where investigators have explored the consequences of designing a cohort study by restricting to incident users, but most of the discussion has been informed by expert opinion, not by systematic evidence. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

The use of healthcare databases in research provides advantages such as increased speed, lower costs and limitation of some biases. However, database research has its own challenges as studies must be performed within the limitations of resources, which often are the product of complex healthcare systems. The primary purpose of this document is to assist in the selection and use of data resources in pharmacoepidemiology, highlighting potential limitations and recommending tested procedures. This guidance is presented as a detailed text with a checklist for quick reference and covers six areas: selection of a database, use of multiple data resources, extraction and analysis of the study population, privacy and security, quality and validation procedures and documentation. Copyright © 2011 John Wiley & Sons, Ltd.

Rationale: Mechanically ventilated intensive care unit (ICU) patients are frequently managed using a continuous-infusion sedative. Although recent guidelines suggest avoiding benzodiazepines for sedation, this class of drugs is still widely used. There are limited data comparing sedative agents in terms of clinical outcomes in an ICU setting. Objectives: Comparison of propofol to midazolam and lorazepam in adult ICU patients. Methods: Data were obtained from a multicenter ICU database (2003–2009). Patient selection criteria included age greater than or equal to 18 years, single ICU admission with single ventilation event (>48 h), and treatment with continuously infused sedation (propofol, midazolam, or lorazepam). Propensity score analysis (1:1) was used and mortality measured. Cumulative incidence and competing risk methodology were used to examine time to ICU discharge and ventilator removal. Measurements and Main Results: There were 2,250 propofol-midazolam and 1,054 propofol-lorazepam matched patients. Hospital mortality was statistically lower in propofol-treated patients as compared with midazolam- or lorazepam-treated patients (risk ratio, 0.76; 95% confidence interval [CI], 0.69–0.82 and risk ratio, 0.78; 95% CI, 0.68–0.89, respectively). Competing risk analysis for 28-day ICU time period showed that propofol-treated patients had a statistically higher probability for ICU discharge (78.9% vs. 69.5%; 79.2% vs. 71.9%; P < 0.001) and earlier removal from the ventilator (84.4% vs. 75.1%; 84.3% vs. 78.8%; P < 0.001) when compared with midazolam- and lorazepam-treated patients, respectively. Conclusions: In this large, propensity-matched ICU population, patients treated with propofol had a reduced risk of mortality and had both an increased likelihood of earlier ICU discharge and earlier discontinuation of mechanical ventilation.

Objective: Rheumatoid arthritis (RA) and its treatments are associated with an increased risk of infection, but it remains unclear whether these factors have an impact on the risk or severity of COVID‐19. The present study was undertaken to assess the risk and severity of COVID‐19 in a US Department of Veterans Affairs (VA) cohort of patients with RA and those without RA.Methods: A matched cohort study using national VA data was conducted. Patients diagnosed as having RA were identified among nondeceased individuals who were active in the VA health care system as of January 1, 2020 and who had received care in a VA medical center in 2019; patients for whom no RA diagnostic code was indicated were matched to the RA patients (1:1) by age, sex, and VA site (non‐RA controls). Patients diagnosed as having COVID‐19 and those with severe COVID‐19 (defined as requiring hospitalization or leading to death) were ascertained from a national VA COVID‐19 surveillance database through December 10, 2020. Multivariable Cox models were used to compare the risk of COVID‐19 and COVID‐19 hospitalization or death between RA patients and non‐RA controls, after adjusting for demographic characteristics, comorbidities, health care utilization and access, and county‐level COVID‐19 incidence rates.Results: This VA cohort of RA patients and non‐RA controls (n = 33,886 subjects per group) predominantly comprised male patients (84.5%), and the mean age was 67.8 years. During follow‐up, 1,503 patients in the cohort were diagnosed as having COVID‐19; among them, 388 patients had severe COVID‐19 (hospitalization or death), while in 228 patients, the deaths were not related to COVID‐19. In the multivariable model, RA was associated with a higher risk of COVID‐19 (adjusted hazard ratio [HR] 1.25 [95% confidence interval (95% CI) 1.13–1.39]) and a higher risk of COVID‐19 hospitalization or death (adjusted HR 1.35 [95% CI 1.10–1.66]) as compared to non‐RA controls. Use of disease‐modifying antirheumatic drugs and prednisone, as well as self‐reported Black race, self‐reported Hispanic ethnicity, and presence of several chronic conditions, but not seropositivity for RA autoantibodies, were each associated with risk of COVID‐19 and severe COVID‐19 (hospitalization or death).Conclusion: Patients with RA are at higher risk of developing COVID‐19 and severe COVID‐19 (leading to hospitalization or death) compared to those without RA. With a risk of COVID‐19 that approaches that of other recognized chronic conditions, these findings suggest that RA patients should be prioritized for COVID‐19 prevention and management strategies.