All-cause mortality rate in patients with idiopathic pulmonary fibrosis. Implications for the design and execution of clinical trials
TE King Jr, C Albera, WZ Bradford… - American journal of …, 2014 - atsjournals.org
American journal of respiratory and critical care medicine, 2014•atsjournals.org
Rationale: FVC has emerged as a standard primary endpoint in clinical trials evaluating
novel therapies for patients with idiopathic pulmonary fibrosis (IPF). However, it has recently
been proposed that all-cause mortality or a composite comprised of all-cause mortality and
all-cause nonelective hospitalization be adopted as the standard primary endpoint for IPF
clinical trials. Objectives: To conduct a comprehensive evaluation of mortality in three phase
3 clinical trials and evaluate the feasibility of mortality trials in patients with IPF. Methods …
novel therapies for patients with idiopathic pulmonary fibrosis (IPF). However, it has recently
been proposed that all-cause mortality or a composite comprised of all-cause mortality and
all-cause nonelective hospitalization be adopted as the standard primary endpoint for IPF
clinical trials. Objectives: To conduct a comprehensive evaluation of mortality in three phase
3 clinical trials and evaluate the feasibility of mortality trials in patients with IPF. Methods …
Rationale: FVC has emerged as a standard primary endpoint in clinical trials evaluating novel therapies for patients with idiopathic pulmonary fibrosis (IPF). However, it has recently been proposed that all-cause mortality or a composite comprised of all-cause mortality and all-cause nonelective hospitalization be adopted as the standard primary endpoint for IPF clinical trials.
Objectives: To conduct a comprehensive evaluation of mortality in three phase 3 clinical trials and evaluate the feasibility of mortality trials in patients with IPF.
Methods: The study population included 622 patients randomized to placebo in the CAPACITY studies evaluating pirfenidone (n = 347) or the INSPIRE study evaluating interferon-γ1b (n = 275). The Kaplan-Meier estimate of 2-year survival was fit to the exponential distribution and used to calculate sample size requirements for a mortality study with 90% power to detect a 25% reduction in all-cause mortality with a two-sided α of 0.05. Modeling analyses were used to assess the effects of selected variables on sample size and study design.
Measurements and Main Results: A total of 73 deaths occurred during the period of observation (mean duration of follow-up, 80.1 wk). The all-cause mortality rate was 6.6% at 1 year and 13.7% at 2 years. Based on the observed 2-year mortality rate, a total of 508 events would be required to detect a significant treatment benefit in a two-arm trial with 90% power to detect a 25% reduction in all-cause mortality. The estimated sample size for a trial enrolled over 3 years with a maximum follow-up period of 5 years is 2,582 patients.
Conclusions: The all-cause mortality rate is relatively low in patients with IPF with mild to moderate impairment in lung function. Accordingly, the necessary size, duration, and cost of all-cause mortality trials in this population are substantial and likely prohibitive.
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