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The effect of anti-acid therapy on survival in idiopathic pulmonary fibrosis: a methodological review of observational studies.

Research paper by Tanja T Tran, Samy S Suissa

Indexed on: 05 May '18Published on: 05 May '18Published in: European Respiratory Journal



Abstract

International treatment guidelines for idiopathic pulmonary fibrosis (IPF) give a conditional recommendation for anti-acid therapy. As some observational studies reported discrepant findings on the effectiveness of anti-acid therapy on mortality in IPF, we reviewed all studies to evaluate whether immortal time bias explains these discrepancies. We searched the EMBASE AND MEDLINE databases until July 2017 for observational studies assessing the effectiveness of anti-acid therapy on mortality in IPF. Hazard ratios of mortality with anti-acid therapy were pooled across studies using random-effect models, stratified by the presence of immortal time bias. We identified 10 observational studies. Four of the five studies reporting beneficial effects of anti-acid therapy use on mortality were affected by immortal time bias (pooled hazard ratio 0.46; 95% CI 0.30-0.69), while the fifth was unclear. The five studies that avoided immortal time bias reported no effect of anti-acid therapy on mortality (pooled hazard ratio 0.99; 95% CI 0.81-1.22). The apparent beneficial effects of anti-acid therapy on mortality in patients with IPF result from observational studies affected by immortal time bias. The effectiveness of anti-acid therapy in IPF thus remains uncertain and needs to be reassessed with more accurate observational study methods and randomised trials. Copyright ©ERS 2018.