Mycophenolate therapy in interstitial pneumonia with autoimmune features: a cohort study

Abstract

Objectives: International experts recently characterized interstitial pneumonia with autoimmune features (IPAF) as a provisional diagnosis for patients with interstitial lung disease who have characteristics of autoimmune disease but do not meet criteria for a specific autoimmune disease. We describe clinical characteristics of IPAF patients and examine responses to mycophenolate as a therapy for IPAF.

Methods: This retrospective cohort included adult patients meeting European Respiratory Society/American Thoracic Society classification criteria for IPAF. Sociodemographic, clinical, and pulmonary function test data were abstracted for patients with and without mycophenolate treatment and followed longitudinally from interstitial lung disease diagnosis for change in pulmonary function test results.

Results: We identified 52 patients who met criteria for IPAF. Of 52 IPAF patients, 24 did not receive mycophenolate and 28 did, with median time to mycophenolate treatment 22 months. Changes in FVC% and percentage predicted lung diffusion capacity for carbon monoxide (D_LCO%) between the mycophenolate-treated and untreated groups were not significantly different (FVC% change P=0.08, D_LCO% change P=0.17). However, there was a trend toward more rapid baseline decline of both FVC% and D_LCO% in the mycophenolate-treated cohort before vs after mycophenolate therapy. The slope of both FVC% and D_LCO% values improved after onset of mycophenolate exposure for the treated group, although this finding was not statistically significant.

Conclusion: Patients with IPAF might benefit from mycophenolate therapy. Larger prospective clinical trials are needed to evaluate the efficacy of mycophenolate for patients who meet criteria for IPAF.

Keywords: autoimmune disease; connective tissue disease; interstitial lung disease; mycophenolate.

Figure 1

Exclusion and inclusion of patients who met criteria for IPAF diagnosis and saw both pulmonology and rheumatology departments within the University of Wisconsin health system. Note: *Three patients saw a pulmonologist familiar with rheumatologic disease and were considered to fill both rheumatologic and pulmonary visit requirements. Abbreviations: ILD, interstitial lung disease; IPAF, interstitial pneumonia with autoimmune features; UW, University of Wisconsin.

Figure 2

(A) Raw FVC% months after IPAF diagnosis in the mycophenolate-unexposed (n=24) group, graphed individually in light gray, with mean is represented by the bold black line. (B) Raw FVC% in the mycophenolate exposed (n=27) groups, graphed individually in light gray, with mean represented by the bold black line. (C) Linear regression of FVC% months from the date of diagnosis in both the mycophenolate-exposed and unexposed groups. (D) Raw D_LCO% months after diagnosis date in the mycophenolate-unexposed (n=19) group, graphed individually in light gray, with mean represented by the bold black line. (E) Raw D_LCO% in the mycophenolate-exposed (n=26) group, graphed individually in light gray, with mean represented by the bold black line. (F) Linear regression of D_LCO% over time from the date of diagnosis in both the mycophenolate-exposed and unexposed groups. Abbreviations: D_LCO, diffusion capacity of lungs for carbon monoxide; IPAF, interstitial pneumonia with autoimmune features.

Figure 3

(A) Raw FVC% in months before and after mycophenolate exposure among the mycophenolate-exposed. Data graphed individually (n=26) in light gray, and mean with SEM represented with the bold black line. (B) Linear regression of FVC% before and after mycophenolate exposure with SD. (C) D_LCO% before and after mycophenolate exposure, graphed individually (n=26) in light gray and mean with SEM represented with the bold black line. (D) Linear regression of D_LCO% before and after mycophenolate exposure with SD. Abbreviations: D_LCO, diffusion capacity of lungs for carbon monoxide.