Serum inflammatory markers as predictors of therapeutic response in non-idiopathic pulmonary fibrosis fibrotic interstitial lung disease: a retrospective cohort analysis.

BACKGROUND

The role of chronic inflammation in non-idiopathic pulmonary fibrosis fibrotic interstitial lung disease (non-IPF f-ILD) remains unclear, with varied responses to anti-inflammatory or immunosuppressive therapy. A reliable predictor for guiding treatment response may enhance clinical decision-making and minimize adverse treatment effects. We hypothesized that elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) may be associated with improved treatment response.

METHODS

Our retrospective cohort study compared treatment response to anti-inflammatory therapy in patients with non-IPF f-ILD stratified by baseline CRP and ESR levels. Treatment response was defined as: (1) relative increase in percent predicted forced vital capacity (FVC%) ≥ 5% in 6 months or ≥ 10% in 12 months; or (2) no change or any increase in FVC% if FVC% decline was noted prior to treatment. Logistic regression was used to delineate outcome predictors with FVC% change over time assessed with linear mixed effects models.

RESULTS

Of 832 non-IPF f-ILD patients screened, 167 received anti-inflammatory therapy and baseline inflammatory marker testing stratified into high vs. low-to-normal groups (104 vs. 63, respectively). Median age was 64 years, and 57% were diagnosed with a systemic autoimmune rheumatic disease (SARD). Treatment response was greater in those with elevated inflammatory markers (56% vs. 35%; OR 2.45 [1.243-4.828] P = 0.010) even after adjustment for a priori covariables. SARD diagnosis was associated with treatment response (OR 2.90 [1.45-5.81] P = 0.003), independent of inflammatory marker level. A positive FVC% slope was observed in treated patients with initially elevated inflammatory markers (P = 0.003).

CONCLUSION

Patients with non-IPF f-ILD and elevated inflammatory markers appear to be more responsive to anti-inflammatory therapy with slower FVC decline over time. These findings suggest baseline serum ESR and CRP may be feasible and reliable predictors of treatment response in certain subgroups.