Smoking and Passive Smoke Linked to Higher Mortality in IPF

SMOKING exposure was associated with higher mortality among people with idiopathic pulmonary fibrosis in a large UK cohort.

Idiopathic Pulmonary Fibrosis and Smoking Exposure

Researchers analyzed 270,644 participants from the UK Biobank to examine whether active and passive smoking exposures were associated with all-cause and cause-specific mortality among people with and without ever-recorded idiopathic pulmonary fibrosis (IPF).

Smoking exposures included baseline smoking status, cumulative pack-years, maternal smoking around birth, adult secondhand smoke, and a composite measure of passive smoke exposure. Models accounted for demographic, socioeconomic, lifestyle, and genetic factors.

Over a median follow-up of 13.8 years, 20,959 participants died. Ever-recorded IPF was strongly associated with all-cause mortality, with a hazard ratio of 4.255 compared with participants without recorded IPF. Active and passive smoking measures were also associated with mortality.

Maternal Smoking Signal Emerges for Respiratory Mortality

When investigators assessed whether smoking exposure and IPF produced mortality effects beyond the sum of their individual associations, a positive additive interaction emerged only for maternal smoking around birth and respiratory mortality.

The relative excess risk due to interaction was 16.969, while the attributable proportion due to interaction was 0.248 and the synergy index was 1.337. Similar positive estimates were observed when analyses were restricted to White participants, participants with complete covariate data, and after deaths within the first 2 years of follow-up were excluded.

However, confidence intervals for the other additive interaction estimates included zero, limiting evidence that other smoking exposures meaningfully interacted with recorded IPF.

Findings Support Attention to Smoking History in IPF

Dose response patterns also differed by IPF status. Associations between smoking exposure and mortality were nonlinear among participants without recorded IPF and approximately linear among those with recorded IPF, although estimates in the IPF group were less precise.

For clinicians, the findings reinforce the importance of capturing both active smoking history and secondhand smoke exposure when assessing people with IPF. The maternal smoking finding may also point toward early life exposure as a potential area for future investigation.

The authors cautioned that this observational analysis cannot establish causation or biological synergy. The interaction involving maternal smoking and respiratory mortality should therefore be considered hypothesis generating and requires confirmation in independent cohorts.

Reference
Tu Q et al. Smoking exposures and mortality risk in individuals with idiopathic pulmonary fibrosis: a UK Biobank cohort study. Front Public Health. 2026;14:1884390.

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