Interstitial lung abnormality with preserved pulmonary function in lung cancer screening-eligible individuals: long-term effects on function and prognosis.

[OBJECTIVES] To evaluate the effect of CT progression of interstitial lung abnormality (ILA) and ILA subtypes on pulmonary function and mortality in lung cancer screening (LCS) participants with preserved pulmonary function.

[MATERIALS AND METHODS] Consecutive participants who met the 2021 United States Preventive Services Task Force guidelines for LCS during a medical check-up between 2012 and 2014 were retrospectively analyzed. Forced vital capacity (FVC) ≥ 80% at baseline was considered indicative of preserved pulmonary function. CT progression and ILA subtype were evaluated for their association with an FVC decline to < 80% and mortality using multivariable time-dependent Cox analysis.

[RESULTS] Among the 6332 LCS participants, 133 with baseline FVC ≥ 80% and follow-up CT and FVC data were included. CT progression was observed in 81.8% (54/66) of those with ILA and 67.2% (45/67) of those with equivocal ILA, with median follow-ups of 61.0 and 76.0 months, respectively. FVC decline to < 80% occurred in 21.1% (28/133) with a median time of 61.4 months. It was associated only with baseline FVC (hazard ratio (HR), 0.78; p < 0.001), while CT progression (p = 0.720) and fibrotic ILA (p = 0.066) were not. For mortality, both CT progression (HR, 8.74; p < 0.001) and a relative FVC decline ≥ 10% (HR, 10.30; p < 0.001) were independent risk factors, whereas fibrotic ILA was not (p = 0.254).

[CONCLUSION] CT progression was a risk factor for mortality, although it was not associated with a decline in FVC to below 80% in participants with preserved lung function. Monitoring CT progression in LCS would be helpful for risk stratification of participants with ILA.

[KEY POINTS] Question Does interstitial lung abnormality (ILA) CT progression affect pulmonary function decline and mortality, even when pulmonary function is preserved? Findings When pulmonary function was preserved, CT progression was not associated with forced vital capacity decline but was an independent risk factor for mortality. Clinical relevance Monitoring CT progression during lung cancer screening adherence could aid in risk stratification for participants with ILA.