POS0551 MEDICAL COSTS FOR PATIENTS STARTING TREATMENT FOR RHEUMATOID ARTHRITIS WHO HAVE COMORBID DIABETES MELLITUS IN JAPAN

Abstract

Background:Rheumatoid arthritis (RA) patients can experience various comorbidities1. The incidence of diabetes mellitus (DM) is reported higher in patients with RA2 and comorbid DM is likely to affect treatment outcomes3 and then healthcare resource uses, however, no previous study has not focused on it.Objectives:To evaluate medical costs and resource use in patients starting treatment for RA with and without DM using a large claims database in Japan.Methods:We used a large Japanese administrative claims database constructed by the Japan Medical Data Center (JMDC)4. Patients with the International Classification of Diseases 10th revision (ICD-10) codes for RA who started medication with disease-modifying antirheumatic drugs (DMARDs) after 6 months without them in the period from 1/1/2012 to 12/31/2017 and who were observable for 12 months as a follow-up period were enrolled. These patients were categorized as DM or non-DM group with ICD-10 codes for DM plus use of antidiabetic drugs in 6 months before starting DMARDs (baseline period). To adjust baseline characteristics between the 2 groups, they were matched by sex, age, Charlson Comorbidity Index (CCI) except for DM, months from the first RA codes to starting DMARDs, and medications. The primary endpoint was mean medical cost per patient in the 12-month follow-up period. Costs in JPY were converted into EUR (1 EUR = 125 JPY in 2020). Costs for drugs, treatments, and materials and their subcategories were evaluated both with and without DM-specific costs. The secondary endpoints were the proportions of patients using the subcategories of each resource.Results:Patients of 161 for the DM group and 2,974 for the non-DM group were eligible, and 109 patients were matched from each group. The medians of age and CCI were 59 years and 2.0 in both groups and no significant difference was observed in all baseline characteristics used for matching between the groups. Total mean costs were significantly higher in the DM group (DM, 5,331 EUR, non-DM 3,200 EUR; P< 0.05). After excluding DM-specific costs, drug costs were significantly higher in the DM group than in the non-DM group (DM 1,883 EUR, non-DM 896 EUR; P < 0.05), especially costs for biological DMARDs (DM 1,156 EUR, non-DM 292 EUR; P < 0.05), mainly because a higher proportion of patients used these drugs in the DM group (Table 1). Treatment costs (DM 2,380 EUR, non-DM 2,133 EUR) and material costs (DM 74 EUR, non-DM 149 EUR) were not different between the groups, but only costs for examinations were significantly higher in the DM group (DM 970 EUR, non-DM 779 EUR; P < 0.05).Table 1.Number and proportion of patients who used drugsType of drugDrug use, n (%)DM (N = 109)Non-DM (N = 109)P-valuecsDMARDsTotal109 (100.0)109 (100.0)1.000Methotrexate101 (92.7)102 (93.6)1.000Others46 (42.2)51 (46.8)0.583bDMARDsTotal16 (14.7)6 (5.5)0.041TNFi11 (10.1)4 (3.7)0.118IL6i6 (5.5)2 (1.8)0.219T-cell4 (3.7)0 (0.0)0.125tsDMARDs0 (0.0)0 (0.0)1.000CSs65 (59.6)62 (56.9)0.711AnalgesicsTotal103 (94.5)96 (88.1)0.167Acetaminophen24 (22.0)23 (21.1)1.000Acetaminophen /Opioids10 (9.2)6 (5.5)0.454NSAIDs102 (93.6)93 (85.3)0.093Opioids0 (0.0)4 (3.7)0.125Others25 (22.9)17 (15.6)0.185bDMARDs=biological disease-modifying antirheumatic drugs; CSs=corticosteroids; csDMARDs=conventional synthetic disease-modifying antirheumatic drugs; DM=diabetes mellitus; IL6i=interleukin-6 inhibitor; NSAID=non-steroidal anti-inflammatory drug; T-cell=selective T-cell co-stimulation modulator; TNFi=tumor necrosis factor α inhibitor; tsDMARDs=targeted synthetic disease-modifying antirheumatic drugs; P-values were calculated using McNemar testConclusion:Medical costs for RA were higher in the DM group than in the non-DM group because of more prevalent use of biological DMARDs in the DM group.