Intravenous cyclophosphamide in acute exacerbation of rheumatoid arthritis-related interstitial lung disease: A propensity-matched analysis using a nationwide inpatient database

Abstract

ObjectivesWe aimed to investigate the effect of intravenous cyclophosphamide (CYC) as the initial therapy in patients with acute exacerbation of rheumatoid arthritis-related interstitial lung disease. MethodsThis was a retrospective observational study. Using the Japanese Diagnosis Procedure Combination inpatient database from July 2010 to March 2018, we identified patients with acute exacerbation of rheumatoid arthritis-related interstitial lung disease (RA-ILD) who received high-dose methylprednisolone within 3 days after admission. RA-ILD was defined as having either the diagnosis of RA-ILD or the diagnoses of both RA and ILD, based on the ICD-10 codes recorded by attending physicians. Patients were divided into two groups: those receiving intravenous CYC within 3 days after admission (CYC group) and those who did not (control group). One-to-four propensity-score matching analyses were performed. ResultsA total of 6130 eligible patients were included. After propensity score matching, 129 patients in the CYC group and 516 patients in the control group were further analyzed. 90-day in-hospital mortality, defined as all-cause mortality during hospitalization within 90 days after admission, was not significantly different between the CYC and control groups (50.4% versus 42.2%, hazard ratio 1.20, 95% confidence interval 0.91–1.58). A larger proportion of patients in the CYC group received platelet transfusion than that in the control group (7.0% versus 2.3%, odds ratio 3.05, 95% confidence interval 1.20–7.73). ConclusionIn this retrospective database study, the initial therapy with CYC did not show a survival benefit in patients with acute exacerbation of RA-ILD. CYC was associated with a larger proportion of platelet transfusion.