Paraseptal Emphysema and Interstitial Lung Abnormalities in AGES-Reykjavik Study

BACKGROUND: Paraseptal emphysema (PSE) is often underrecognized because it has minimal impact on pulmonary function. Recent studies suggest its frequent coexistence with interstitial lung abnormalities (ILA) and potential clinical significance, yet population-based data on its prevalence and prognostic impact remain unclear. PURPOSE: To examine the associations between visual emphysema subtypes and ILA, and to evaluate the prognostic impact of ILA in individuals with emphysema subtypes. MATERIALS AND METHODS: We analyzed 5,059 participants from Age Gene/Environment Susceptibility Reykjavik Study. Emphysema was classified as no emphysema, pure PSE, mixed emphysema, or pure centrilobular emphysema (CLE), and ILA as no ILA, indeterminate ILA, or ILA. Associations were assessed using multivariable logistic regression, and all-cause mortality was evaluated with Kaplan-Meier and Cox proportional hazards analyses. RESULTS: Pure PSE prevalence is 5.0%. Pure PSE (adjusted odds ratio [OR], 4.99; 95% confidence interval [CI], 3.30-7.42) and mixed emphysema (adjusted OR, 5.07; 95% CI, 3.71-6.92) were associated with ILA, whereas pure CLE was not. Over a mean follow-up time of 8.3 ± 2.6 years, mixed emphysema was linked to increased mortality compared with no emphysema (adjusted hazard ratio [HR], 1.47; 95% CI, 1.29-1.67). PSE severity was not significantly associated with ILA prevalence or with prognosis. Among PSE and CLE participants, ILA prevalence increased mortality risk (adjusted HR, 1.48 and 1.44, respectively). CONCLUSION: In our large, longitudinal cohort, pure PSE or mixed emphysema is strongly associated with ILA. ILA was consistently associated with increased mortality regardless of emphysema subtype. These findings support the importance of assessing ILA in patients with emphysema as a key marker for risk stratification.