Determinants of pulmonary function improvement in patients with scleroderma and interstitial lung disease

Background Inpatients with scleroderma-related interstitial lung disease (ILD), improvements of pulmonary function have been reported after treatment with cyclophosphamide (CYC) alone or CYC and high-dose steroids. The study objective was to identify therapeutic regimen that alone or in combination with laboratory or clinical characteristics were associated with pulmonary function improvement in these patients. Methods Scleroderma patients with ILD and serial pulmonary function measurements were retrospectively analyzed. We recorded forced vital capacity (FVC, % predicted), diffusion capacity (DLCO, % predicted), type of therapy, and various clinical and laboratory parameters. Treatment with IV CYC was recorded as cumulative dose (grams) and treatment with steroids as high or low dose; outcome was defined as a sustained increase in,FVC (% predicted) >= 10 points. Results Of the 59 patients who were included in the study, 29 (49 %) patients received IV CYC (cumulative dose 13.9 +/- 6.2, range 5.2-26.2 gr) for 3.3 +/- 2.4 years (range 5-60 months). Eighteen out of 59 (30 %) patients received high-dose prednisolone and 41 (70 %) received low-dose prednisolone. In an ordinal logistic model, patients receiving > 12 gr of CYC were 6 times more likely to improve FVC than to decrease or maintain FVC, compared to those who did not receive CYC (p = 0.02). In multivariate analysis, the effect of high dosage CYC on FVC persisted (OR 10.82, p = 0.02). Steroid dosage (high or low) was not associated with FVC improvement (p < 0.05). Conclusion In patients with scleroderma and ILD, treatment with CYC is the only variable that is independently associated with pulmonary function improvement and that prolonged (> 1 year) CYC therapy increases the probability of pulmonary function improvement more than shorter CYC courses.