Interstitial Lung Abnormalities Prevalent in General Population

Interstitial lung abnormalities (ILAs) and subclinical interstitial lung disease (ILD) are prevalent among lung cancer screening (LCS) participants, the general population, and at-risk familial groups, according to a study in the American Journal of Respiratory and Critical Care Medicine.

Researchers conducted a systematic review and meta-analysis to estimate the pooled prevalence of ILAs during LCS, in the general population, and in at-risk familial cohorts. The reviewers searched Embase and Medline from inception until May 11, 2023, for relevant studies published in English.

Eligible studies included adults aged who had chest computed tomography (CT) imaging. The pooled prevalence of ILAs was estimated with use of a random effects model, and risk factors were determined with meta regression.

The systematic review identified 35 studies, and data were extracted from 22 studies for the largest cohort or most recent publication. The pooled prevalence analysis included 88,325 participants. A total of 10 studies and 30,909 participants were included from LCS cohorts, 8 studies and 56,817 participants were included in the general population cohort, and 5 studies and 599 participants from 240 kindred were included in the at-risk familial cohort.

The prevalence of ILA was 7% (95% CI, 0.01-0.13) in the LCS cohort and 7% (95% CI, 0.04-0.10) in the general population. The prevalence of subclinical ILD was 26% (95% CI, 0.20-0.32) in the familial cohort. Substantial variance due to heterogeneity occurred in the overall cohort (I² = 99.5%, P <.0001), the LCS cohort (I² = 99.6%, P <.0001), and the general population group (I² = 98.3%, P <.0001), which was lower in the familial cohort (I² = 53.4%, P =.09). For all cohorts, the overall pooled prevalence was 10% (95% CI, 0.07-0.13, I² = 99.5%).

Overall, 44.9% of participants with ILAs were female, their mean (SD) age was 65.2 (9.6) years, and the mean forced vital capacity percentage (FVC%) predicted was 99.1 (2.8); among those without ILAs, 43.2% were female, the mean age was 56.1 (20.5) years, and mean FVC% predicted was 101.2 (4.4). An increased prevalence of ILAs was associated with increased age (weighted mean difference [MD], 2.22; 95% CI, 1.89-2.54), lower FVC% predicted (weighted MD, -1.72; 95% CI, -3.00 to -0.45), and male sex (risk ratio 0.84; 95% CI, 0.71-0.94).

The pooled mortality risk was increased among individuals with ILAs vs those without (odds ratio 3.56; 95% CI, 2.19-5.81) during a median follow-up of 5 years (range, 2-11).

The researchers noted that the findings may be of moderate certainty owing to estimated between-study heterogeneity. In addition, the meta-regression results were likely affected by weighting of parent studies due to heterogenous sample sizes, and CT scan techniques varied among the studies.

“Populations undergoing imaging for non-ILD indications demonstrate high ILA

prevalence. Standardized reporting and follow-up of ILAs is needed, including defining those at greatest risk of progression to ILD,” the study authors concluded.

This article originally appeared on Pulmonology Advisor