A39-31 Predictors of Treatment Response to Antifibrotic Therapy in Patients With Idiopathic Pulmonary Fibrosis

Abstract Rationale Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing interstitial lung disease of unknown cause, characterized by worsening dyspnea, decline in lung function, and poor prognosis. Median survival is approximately 3-5 years from diagnosis, making it one of the most lethal pulmonary disorders. Antifibrotic agents such as pirfenidone and nintedanib are currently the standard of care, slowing but not reversing disease progression. However, treatment response varies considerably among individuals. Identifying baseline predictors of response could facilitate individualized treatment strategies, timely therapeutic adjustments, and improved patient outcomes. Methods We conducted a retrospective analysis of consecutive patients diagnosed with IPF at our institution between 2012 and 2020. Eligible patients had received antifibrotic therapy for ≥3 months and completed baseline and follow-up pulmonary function tests (PFTs). Clinical characteristics, laboratory values, PFT parameters, and high-resolution computed tomography (HRCT) patterns were collected at baseline. Disease deterioration within one year was defined as worsening symptoms, radiologic progression, or ≥ 5% absolute decline in FVC. Logistic regression was used to explore potential predictors of poor response. Results Forty-seven patients (32 men, 15 women; mean age 74.3 ± 1.1 years) were included; 63.8% were ever-smokers (mean 31.7 ± 4.7 pack-years). The mean modified MRC dyspnea score was 1.5 ± 0.2. Laboratory data showed mean WBC 7262 ± 328.6/μL, monocytes 461 ± 48.6/μL, LDH 246 ± 8.9 U/L, and KL-6 1568 ± 315.5 U/mL. PFT results included mean %PEF 77.9 ± 4.4, %TLC 73.9 ± 2.6, %FVC 72.2 ± 2.7, and %DLco 63.7 ± 4.8. HRCT patterns were definite UIP in 20 patients, probable UIP in 19, and indeterminate in 8. Lower baseline %PEF (OR 0.977, p = 0.097) and %TLC (OR 0.953, p = 0.071) were associated with deterioration within one year. Over a median follow-up of 24 months, the median survival was 47 months. Patients with preserved %PEF and %TLC tended to have a slower rate of functional decline. Conclusions Lower %PEF and %TLC at baseline may predict a poorer clinical response to antifibrotic therapy in IPF. These readily obtainable PFT indices could serve as practical, noninvasive markers for risk stratification and early intervention. Prospective, multicenter studies are warranted to confirm their predictive value and to integrate them into clinical decision-making algorithms. This abstract is funded by: None