Title Treatment of rheumatoid arthritis in the Medicare Current Beneficiary Survey Permalink

Introduction: Numerous studies across different health systems have documented that many patients with rheumatoid arthritis (RA) do not receive disease-modifying anti-rheumatic drugs (DMARDs). Relatively little is known about correlates of DMARD use and whether there are socioeconomic and demographic disparities. We examined DMARD use during 2001 to 2006 in the Medicare Current Beneficiary Survey (MCBS), a longitudinal US survey of randomly selected Medicare beneficiaries. Methods: Participants in MCBS with RA were included in the analyses, and DMARD use was based on an in-home assessment of all medications. Variables included as potential correlates of DMARD use in weighted regression models included race/ethnicity, insurance, income, education, rheumatology visit, region, age, gender, comorbidity index, and calendar year. Results: The cohort consisted of 509 MCBS participants with a diagnosis code for RA. Their median age was 70 years, 72% were female, and 24% saw a rheumatologist. Rates of DMARD use ranged from 37% among those <75 years of age to 25% of those age 75 to 84 and 4% of those age 85 and older. The multivariable adjusted predictors of DMARD use include: visit with a rheumatologist in the prior year (odds ratio, OR, 7.74, 95% CI, 5.37, 11.1) and older patient age (compared with <75 years, ages 75 to 84, OR 0.58, 95% CI 0.37, 0.92, and 85 and over, OR 0.09, 95% CI 0.02, 0.31). In those without a rheumatology visit, lower income and older age were associated with a significantly reduced probability of DMARD use; no association of DMARD use with income or age was observed for subjects seen by rheumatologists. Race and ethnicity were not significantly associated with receipt of DMARDs. Conclusions: Among individuals not seeing rheumatologists, lower income and older age were associated with a reduced probability of DMARD use. Introduction Rheumatic disease experts and their professional societies widely embrace the importance of early and sustained use of disease-modifying antirheumatic drugs (DMARDs) for rheumatoid arthritis (RA) [1,2]. Despite this recommendation, several population-based and community-based studies demonstrate under-use of these agents. Several large studies of community-based practice suggest that rates of DMARD use may be no higher than 50% [3-5], with some evidence of recent improvement [6,7]. A more complete understanding of patterns of DMARD use could inform potential quality improvement interventions. Studies that have assessed correlates of under-use have identified several important variables. A prior study within the Medicare population and another using data from health plans suggested that specific race/ethnicity groups, such as black race, was associated with underuse [4,6]. The largest study of this topic used data from Medicare Managed Care plans enrolled in the National Committee on Quality Assurance’s Healthcare Effectiveness Data and Information Set (HEDIS) program [6]. This study found several patient characteristics associated with lower DMARD use, including black race, lower income, and older age. All studies that have examined the inclusion of a rheumatologist in a patient’s care have found this factor to be the strongest predictor * Correspondence: dsolomon@partners.org Division of Rheumatology, Immunology, and Allergy, Brigham and Women’s Hospital, 75 Francis Street, Boston MA, 02115, USA Full list of author information is available at the end of the article Solomon et al. Arthritis Research & Therapy 2013, 15:R43 http://arthritis-research.com/content/15/2/R43 © 2013 Solomon et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. of DMARD use, with a 2to 7-fold increase in prescribing among patients seeing a rheumatologist [4,5,7,8]. These findings are consistent across various countries. Just as with other health care interventions, including total joint replacement, cardiac revascularization and organ transplant, vulnerable populations (people at high risk for disparities in health and health care delivery, typically including groups categorized by age, gender, race, ethnicity, geography, and disability status) appear to receive DMARDs less often than the general population [9-11]. DMARDs are recommended as the standard of care for RA and have been shown to improve function and reduce pain. Thus, differences in care can be described as treatment disparities, which have been defined as ‘racial or ethnic differences in the quality of healthcare that are not due to access-related factors of clinical needs, preferences, and appropriateness of intervention’ [12]. We examined potential disparities in DMARD use for RA in the Medicare Current Beneficiary Survey (MCBS), a large representative survey of Medicare beneficiaries in the US. The goal of these analyses was to identify potential demographic and socioeconomic disparities in DMARD use in the total cohort and within the sub-groups of individuals who did and did not see a rheumatologist. Methods Study cohort and design The MCBS is conducted by the Center for Medicare and Medicaid Services on a representative sample of Medicare beneficiaries, excluding those exclusively in Medicare Advantage Plans (a Medicare health plan offered by a private company that contracts with Medicare to provide all physician and hospital benefits). Beneficiaries are visited in their homes and instructed to keep all paperwork related to medical services. Each year since 1992, approximately 4,000 to 6,000 Medicare beneficiaries have been recruited and then surveyed annually for four consecutive years. They assure its representativeness through a strategic sampling procedure. The MCBS sample is selected through a three-stage process that results in a sample of individuals who are more likely to live close to each other than a random draw of individuals. In the first stage, primary sampling units are selected consisting of metropolitan statistical areas or clusters of nonmetropolitan counties. In the second stage, ZIP code clusters are sampled within the primary sampling unit. In the third stage, beneficiaries are sampled within the ZIP code clusters. The MCBS also oversamples individuals under age 65 years (disabled) and age 85 or older (the oldest old) to increase the precision of estimates for these groups. The survey includes sociodemographic information, medical illnesses, insurance information, region of residence, and medication use. There are few missing data in the MCBS survey, with one recent study finding 2.7% of all data elements missing [13]. In addition to the survey data from MCBS, we also had linked Part A and Part B health care claims from Medicare. This information includes ambulatory and inpatient diagnoses, visits and procedure codes. We used MCBS data from 2000 to 2006. Subjects entering in the last few years did not have complete follow-up over the four years of the survey; we included data from the available years through 2006. Individuals with RA were required to meet two criteria: 1) report RA on the survey and 2) experience a health care claim coded with a diagnosis of RA. Those who were in a Medicare Advantage Plan must have had some period during which individual health care utilization claims were reported. We began follow-up of the study cohort at the first of these two criteria and continued through the end of the four years of surveys, allowing each participant to potentially contribute multiple years of follow-up. We required at least one year of follow-up after qualifying with a diagnosis of RA to determine subsequent DMARD use (the study outcome); thus, our last cases entered the cohort in 2005. Since several of our variables relied on data from the 12 months prior to qualifying for the definition of RA, our earliest cases entered the study cohort in 2001. All of the MCBS data are publically available and do not require subjects’ informed consent. Medicare performs the linkage and de-identifies the dataset. The Partners Healthcare Institutional Review Board approved the study protocol. DMARD use endpoint DMARD use was based on an in-home assessment of all medications by MCBS interviewers. Participants were asked to retain all medication vials and prescription receipts. Detailed information on drug name, strength, and number of tablets was collected at the in-home visits. The medication data reported in the survey were assessed for report of any non-biologic (azathioprine, cyclosporine, d-penicillamine, hydroxychloroquine, leflunomide, methotrexate, and sulfasalazine) or biologic (abatacept, adalimumab, etanercept, infliximab, kineret, and rituximab) DMARDs used during the study time period. We also examined the medication reports for oral glucocorticoids, but these were not included in the DMARD category. Participants were followed over several years and may have used DMARDs in certain years but not in others. Thus, each year of follow-up was considered a separate observation for the endpoint of DMARD use, allowing subjects to contribute multiple endpoints. Potential predictors of DMARD use Sociodemographic We defined several sociodemographic variables as potential predictors of DMARD use. These included age Solomon et al. 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