A39-27 Antifibrotics for Who? Highlighting a Gap in Understanding Current Clinical Practices of Antifibrotic Use With Icd-10 Coding

Abstract Rationale The current indications for antifibrotics are limited. Nintedanib is approved in the United States for Idiopathic Pulmonary Fibrosis (IPF), Chronic Fibrosing ILDs with progressive phenotype, and Systemic Sclerosis - associated ILD (SSc-ILD). Pirfenidone is solely approved for IPF. Pirfenidone and nintedanib have similar efficacy on IPF outcomes, and therapeutic choice is often individual. There is limited clinical data on the underlying diagnoses of patients prescribed anti-fibrotics. Here we examined the different diagnoses underpinning antifibrotic use and characteristics of patients taking pirfenidone versus nintedanib. Methods A retrospective cohort analysis using TriNetX US collaborative Network Adults (≥18 years) documented taking nintedanib (N = 21,181) and pirfenidone (N = 11,501) was performed. The two cohorts were compared for previous documentation of IPF diagnoses: Idiopathic Pulmonary Fibrosis (ICD-10 J84.112), Pulmonary Fibrosis Unspecified (ICD-10 J84.10), Interstitial Lung disease with progressive phenotype (ICD-10 J84.170) and Systemic Sclerosis with lung involvement (IC-10 M34.81). Baseline characteristics, related co-morbid conditions, and relevant medication history were compared between cohorts within five years of antifibrotic use. Differences in indexed IPF diagnoses, baseline characteristics, related conditions, and medications were evaluated with T-tests for means and Chi-Squared Tests for prevalences. Results Within the nintedanib cohort 11,142 (53%) patients had a prior diagnosis of IPF; 927(4%) had a diagnosis of intestinal lung disease with progressive fibrotic phenotype, and 755 (4%) had SSc-ILD. However, a large amount of the patients (n = 14,839;70%) taking nintedanib had a diagnosis of pulmonary fibrosis unspecified. In the cohort taking pirfenidone, 7,990 (69%) had a diagnosis of idiopathic pulmonary fibrosis, 273(2%) had a diagnosis of interstitial lung disease with progressive fibrotic phenotype and 92 (1%) had SSc-ILD documented. Many patients taking pirfenidone had pulmonary fibrosis unspecified (n = 8373;73%) listed as a diagnosis. Between the nintedanib and the pirfenidone cohorts there were differences (p 0.01) in conditions not limited to: emphysema (14% vs. 16%), pulmonary hypertension (30% vs. 28%), and rheumatoid arthritis (10% vs. 6%). (Table 1) Conclusions: Current indications for nintedanib are IPF, chronic fibrosing ILD with progressive phenotype, and SSC-ILD. In the case of pirfenidone, IPF is the only indication. Here we examined characteristics of patients taking pirfenidone and nintedanib. We also show a large subset of patients taking antifibrotics with an ICD-10 code of “pulmonary fibrosis unspecified” suggesting variability in clinical practice and potential off-label use. Current clinical practice, in real world scenarios where ICD-10 codes depict a pattern of misalignment with antifibrotic clinical guidelines, warrants further investigation. This abstract is funded by: None