Community-acquired pneumonia subgroups and differential response to corticosteroids: a secondary analysis of controlled studies

Background Latent class analysis (LCA) has identified subgroups with meaningful treatment implications in acute respiratory distress syndrome. We performed a secondary analysis of three studies to assess whether LCA can identify clinically distinct subgroups in community-acquired pneumonia (CAP) and whether the treatment effect of adjunctive corticosteroids differs between subgroups. Methods LCA was performed on baseline clinical and biomarker data from the Ovidius trial (n=304) and STEP trial (n=727), both randomised controlled trials investigated adjunctive corticosteroid treatment in CAP, and the observational Triple p cohort (n=201). Analyses were conducted independently in two cohorts (Ovidius-TripleP combined and STEP trial). In both cohorts, differences in clinical outcomes and response to adjunctive corticosteroid treatment were examined between subgroups identified through LCA. Results A two-class model fitted both cohorts best. Class 2 patients had more signs of systemic inflammation compared to Class 1. In both cohorts, length of stay was longer and in-hospital mortality rate was higher in Class 2. In the Ovidius trial, corticosteroids reduced median length of stay in Class 2 (6.5 versus 9.5 days) but not in Class 1 (p-value for interaction=0.02). In the STEP trial, there was no significant interaction for length of stay. We found no significant interaction between class assignment and adjunctive corticosteroid treatment for secondary outcomes. Conclusions In two independent cohorts, LCA identified two classes of CAP patients with different clinical characteristics and outcomes. Given the different response to adjunctive corticosteroids in the Ovidius trial, LCA might provide a useful basis to improve patient selection for future trials.