BackgroundSymptoms and prognosis of patients with rheumatoid arthritis (RA) have improved with more intensive therapy, including the biological disease-modifying anti-rheumatic drugs (bDMARDs). Real life data concerning how comorbidities are distributed among patients treated or not treated with bDMARDs are scarce. Our objective was to investigate differences in comorbidity and health care consumption in RA patients, with and without bDMARDs.MethodsThis cross-sectional study was performed in the Southwestern part of Sweden. Patients, aged ≥ 18 years and diagnosed with RA in secondary health care during 2009–2010, were identified in the regional health care database. Aggregated data of comorbidity and health care consumption were retrieved between 2006 and 2010. RA patients treated with bDMARDs on 31st December 2010 were identified in the Swedish Rheumatology Quality Register (SRQ), which includes the biologics register Anti-Rheumatic Therapy in Sweden (ARTIS). Descriptive, comparative, univariate and multiple logistic regression analyses were used to identify factors associated with bDMARDs.ResultsSeven thousand seven hundred and twelve (7712) RA patients were identified (age 64.8 ± 14.9 years, women 74.3%), of whom 1137 (14.7%) were treated with bDMARDs. Overall, the most common comorbidities were infections (69.2%), hypertension (41.1%), chronic respiratory disease (15.3%), ischemic heart disease (14.0%) and malignancy (13.7%). Patients without bDMARDs were older and had more comorbidity. In the multiple logistic regression analysis, older age, cerebrovascular and chronic respiratory disease, heart failure, depression and malignancy were all associated with no present bDMARDs. Infections were associated with bDMARDs. Patients treated with bDMARDs consumed more secondary outpatient care but less visits in primary health care compared to patients without bDMARDs.ConclusionsPatients treated with bDMARDs versus no bDMARDs were younger and had significantly lower period prevalence for most common comorbidities, with the exception of infections. Differences in comorbidities between RA patients with or without bDMARDs should be taken into consideration when evaluating effectiveness and safety of bDMARDs in ordinary care.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-016-1354-7) contains supplementary material, which is available to authorized users.

BackgroundTreatment with biological DMARDs (bDMARDs) in rheumatoid arthritis (RA) is increasing. There is a selection of patients with less comorbidity in randomized controlled trials assessing the effects of bDMARDs. If characteristics differ between RA patients on bDMARDs vs not on bDMARDs in routine care has not been extensively studied.ObjectivesThe aim of this study was to investigate the use of bDMARDs in patients with RA in western Sweden and if characteristics and comorbidity differed between patients receiving bDMARDs and patients who did not in cross-sectional analysis in a population based setting.MethodsPatients, ≥18 years, diagnosed with RA, attending a specialist care unit at least once 2009 through 2010, were identified in the regional health care database, Vega. Cumulative frequencies for in- and outpatient visits with predefined comorbidities were extracted from Vega for the period 2006 through 2010. Patients on bDMARDs 31 December 2010 were identified in the national Swedish biologics register, ARTIS and by linkage also in Vega. Data from ARTIS were validated against the medical records. Descriptive, comparative and multiple logistic regression analysis were used to identify factors significantly associated with biological treatment or not.ResultsA total of 7712 patients with RA were identified out of which 1137 (14.7%) were on bDMARDs. Another 390 patients were identified having bDMARDs, but validation process revealed that they had stopped or planned to begin a bDMARD and were excluded from further analyses. In all, 60% of the patients on bDMARDs were treated with their first bDMARDs and 28% their second. The three most frequently used bDMARDs were Infliximab (36%), etanercept (28%) and rituximab (16%). The patients on bDMARDs had a disease duration of (mean ± SD) 16±11 years, a disease activity score of 28 joints (DAS28) of 3.0±1.3, and had been treated with their present bDMARDs for 41±33 months. Characteristics of the patients are shown in the table. Patients treated with bDMARDs had compared to those not treated lower age and lower occurrence of cerebrovascular, congestive heart, chronic respiratory disease, depression and malignancy in multiple logistic regression models, whereas the occurrence of infectious disease was higher. Sex, presence of diabetes and ischemic heart disease were not significantly different between the two groups.ConclusionsIn western Sweden, 14.7% of RA patients were on bDMARDs 31 December 2010. Those treated with bDMARDs compared to those not were younger and had overall lower occurrences for comorbidities, with the exception for documented infections supporting the overall safety in the manner bDMARDs are used in the population.Disclosure of InterestNone declared