American journal of respiratory and critical care medicine
-
Am. J. Respir. Crit. Care Med. · May 2021
Attention to Immortal Time Bias in Critical Care Research.
Observational studies in critical care medicine offer a popular and practical approach to questions of treatment effectiveness. Although observational research is widely understood to be susceptible to design and interpretation challenges, one well-described source of bias-immortal time bias (ITB)-is frequently present yet often overlooked. ITB may be introduced by study design oversights or mishandled during data analysis. ⋯ Of the eight studies examined, none contained enough design or reporting elements to rule out the presence of ITB. To mitigate the influence of ITB in future observational studies, we present a novel checklist to help readers assess the features of study design, analysis, and reporting that introduce ITB or obscure its presence. We recommend that commonly used tools designed to evaluate observational research studies should include an ITB assessment.
-
Am. J. Respir. Crit. Care Med. · May 2021
Cigarette Smoke Directly Promotes Pulmonary Arterial Remodeling and Kv7.4 Channel Dysfunction.
Rationale: Cigarette smoke is considered the chief leading cause of chronic obstructive pulmonary disease (COPD). Its impact on the progressive deterioration of airways has been extensively studied, but its direct effects on the pulmonary vasculature are less known. Objectives: To prove that pulmonary arterial remodeling in patients with COPD is not just a consequence of alveolar hypoxia but also due to the direct effects of cigarette smoke on the pulmonary vascular bed. ⋯ Most importantly, the levels of this channel were diminished in the lungs of smoke-exposed mice, smokers, and patients with COPD. Conclusions: Cigarette smoke directly contributes to pulmonary arterial remodeling through increased cell senescence, as well as vascular tone alterations because of diminished levels and function in the Kv7.4 channel. Strategies targeting these pathways may lead to novel therapies for COPD.