More lessons from the Lung Health Study

The 32.5-year follow-up of the Lung Health Study (LHS) published in this issue highlights the long-term impact of a well-executed randomized clinical trials (RCTs) evaluating a smoking cessation intervention. Between 1986 and 1989, the LHS enrolled 5887 smokers aged 35-59 with mild-to-moderate airway obstruction across ten North American sites and randomized them to a 10-day smoking cessation intervention with placebo inhaler, the same intervention with ipratropium bromide, or usual care. The latest 32.5-year analysis confirms a reduction in respiratory-related mortality, though the earlier observed all-cause mortality benefit observed at 14.5 years was not seen. The updated analysis excludes 608 participants from the one Canadian clinic and their baseline smoking characteristics differed from the US participants. Regardless, qualitative effect modification is unlikely. Shifts in leading causes of death over time, competing risks, and potential postrandomization selection bias are challenges inherent in extended follow-up, yet the findings of reduced respiratory mortality for participants assigned to smoking cessation stood the test of time. This publication highlights the importance of trial conduct, data preservation, and the value of long-term follow-up using the National Death Index. Congratulations to the authors for this fourth update and to all LHS researchers who contributed to this landmark clinical trial.