Disease burden and treatment sequence of polymyositis and dermatomyositis patients in Japan: a real-world evidence study

Abstract

Introduction/objectivesSince new consensus on polymyositis (PM) and dermatomyositis (DM) were released in Japan, an updated evidence on treatment landscape and PM/DM burden was essential. This study evaluates treatment burden and overall treatment cost of PM/DM-related inpatient and outpatient visits, treatments, and procedures/patient/year.MethodThis retrospective, observational study analyzed insurance claims from Japan Medical Data Center (JMDC) database. Patients with at least one PM/DM diagnosis/one dispensation of treatment between 1 January 2009 and 31 December 2019 were enrolled. Patient characteristics, treatment patterns and sequence, treatment choices, healthcare resource utilization (HCRU), and related costs were assessed. Chi-square test and linear regression model were used to assess impact of patient characteristics on treatment choice.ResultsPatients (836/4,961) receiving a relevant treatment were analyzed. Heart disease (35%), interstitial lung disease (27%), and diabetes mellitus (26%) were frequently identified as comorbidities. Concomitant dispensation of immunosuppressants and systemic steroids was largely found in first and second line of treatment (LoT) while systemic steroids remained as single dominant treatment across all LoTs. HCRU was very low for inpatient visits (0.68 [1.43]) or rehabilitation (4.74 [14.57]). The mean (SD) number of inpatient visits decreased from first (1.23 [2.32]) to third year (0.11 [0.54]). Total mean (SD) healthcare cost per patients per year was ¥ 3,815,912 (7,412,241), with overall drug dispensation compounding to 80% of total cost.ConclusionsHigh concomitant immunosuppressant and systemic steroid prescriptions in first LoT recommend early optimal treatment to manage PM/DM. Although inpatient costs are low, outpatient dispensation costs increase overall economic burden.Key Points• Japan faces treatment challenges in the prognosis of polymyositis (PM) and dermatomyositis (DM) and thus, we assessed the real-world treatment landscape, practice, patterns, and healthcare resource utilization as an evidence to support healthcare outcome improvement and treatment burden reduction.• Systemic steroids were the dominant preferred choice of treatment, but it increases the overall cost of the treatment due to the resultant comorbidities considering possible side-effects promotion.• Thus, an increased awareness towards the disease management among patients and medical doctors is required for better management goals based on this real-world practice evidence.