Association between disease-modifying antirheumatic drugs and diabetes risk in patients with rheumatoid arthritis and psoriasis.

CONTEXT: Rheumatoid arthritis (RA) and psoriasis have been linked with insulin resistance and diabetes mellitus (DM). Prior investigations suggest that systemic immunosuppressive drugs may improve insulin resistance and reduce the risk of DM. OBJECTIVE: To compare the risk of newly recorded DM among participants diagnosed with RA or psoriasis based on use of a variety of disease-modifying antirheumatic drugs (DMARDs). DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort study among 121,280 patients with a diagnosis of either RA or psoriasis on at least 2 visits. The analyses were conducted in the context of 2 large health insurance programs, 1 in Canada and 1 in the United States, using administrative data. The mean follow-up was 5.8 months and began with the first prescription for a DMARD after study eligibility was met. Drug regimens were categorized into 4 mutually exclusive groups: (1) tumor necrosis factor (TNF) inhibitors with or without other DMARDs; (2) methotrexate without TNF inhibitors or hydroxychloroquine; (3) hydroxychloroquine without TNF inhibitors or methotrexate; or (4) other nonbiologic DMARDs without TNF inhibitors, methotrexate, or hydroxychloroquine (reference exposure). MAIN OUTCOME MEASURE: Newly recorded DM as evidenced by a new diagnosis of DM with use of a DM-specific medication. RESULTS: The study cohort consisted of 13,905 participants with 22,493 treatment episodes starting 1 of the categories of DMARD regimens between January 1996 and June 2008. New diabetes cases and respective incidence rates per 1000 person-years were: other nonbiologic DMARDs (55 cases among 3993 treatment episodes; rate, 50.2; 95% confidence interval [CI], 47.3-53.2); TNF inhibitors (80 cases among 4623 treatment episodes; rate, 19.7; 95% CI, 19.1-20.3); methotrexate (82 cases among 8195 treatment episodes; rate, 23.8; 95% CI, 23.0-24.6); and hydroxychloroquine (50 cases among 5682 treatment episodes; rate, 22.2; 95% CI, 21.3-23.1). The multivariate adjusted hazard ratios for DM were 0.62 (95% CI, 0.42-0.91) for TNF inhibitors, 0.77 (95% CI, 0.53-1.13) for methotrexate, and 0.54 (95% CI, 0.36-0.80) for hydroxychloroquine compared with other nonbiologic DMARDS. CONCLUSION: Among patients with RA or psoriasis, the adjusted risk of DM was lower for individuals starting a TNF inhibitor or hydroxychloroquine compared with initiation of other nonbiologic DMARDs.

Cost-effectiveness of abatacept in patients with moderately to severely active rheumatoid arthritis and inadequate response to tumor necrosis factor-alpha antagonists.

OBJECTIVE: To assess cost-effectiveness of abatacept in patients with rheumatoid arthritis (RA) with inadequate response to tumor necrosis factor-alpha antagonists (anti-TNF). METHODS: We developed a simulation model to depict progression of disability [in terms of Health Assessment Questionnaire Disability Index (HAQ-DI)] in women aged 55-64 years with moderately to severely active RA and inadequate response to anti-TNF. At model entry, patients were assumed to receive either oral disease modifying antirheumatic drugs (DMARD) only or oral DMARD plus abatacept. Patients were then tracked from model entry until death. Future health-state utilities and medical-care costs (except study therapy) were estimated based on predicted values of the HAQ-DI. The model was estimated using data from a Phase III clinical trial of abatacept plus secondary sources. Cost-effectiveness was expressed in terms of incremental cost (2006 US$) per quality-adjusted life-year (QALY) gained alternatively over 10 years and a lifetime. Future costs and health effects were discounted at 3% annually. RESULTS: Over 10 years, abatacept would yield 1.0 additional QALY (undiscounted) per patient (4.0 vs 3.0 for oral DMARD) at an incremental (discounted) cost of $45,497 (100,648 vs $55,151) respectively; over a lifetime, corresponding figures were 1.6 QALY (5.8 vs 4.2) and $64,978 ($140,714 vs $82,489). Cost-effectiveness was [mean (95% CI)] $50,576 ($47,056, $54,944) per QALY gained over 10 years, and $45,979 ($42,678, $49,932) per QALY gained over a lifetime. Findings were robust in sensitivity analyses. CONCLUSION: Abatacept is cost-effective by current standards of medical practice in patients with moderately to severely active RA and inadequate response to an anti-TNF.

Frequency, predictors, and economic impact of upward dose adjustment of infliximab in managed care patients with rheumatoid arthritis.

OBJECTIVE: To examine dosing patterns and costs among rheumatoid arthritis (RA) patients newly treated with infliximab in a large national health care claims database. METHODS: Using data from a proprietary database of pharmacy and medical claims for 75 U.S. health plans, RA patients newly treated with infliximab between June 2000 and June 2002 were selected and assigned an .index date. based on the first infusion. A pretreatment period of 6 months was created; patients were also followed for a minimum of 6 months after the initial infusion. Follow-up was allowed to vary beyond this minimum 6 months in order to preserve all available patient data. A maintenance number of infliximab vials was determined as of the second infusion; patients with 1 subsequent increase in vials used or 2 intervals between infusions of <49 days were considered to have had an upward dose adjustment. Differences (i.e., between those with upward dose adjustment and those with no upward dose) in patient characteristics were examined using descriptive statistics. In addition, time to upward dose adjustment and factors influencing its likelihood were analyzed using Kaplan-Meier and Cox proportional hazards techniques. Finally, differences in RA-related and unrelated costs (medication, outpatient, inpatient, and total, expressed in 2003 dollars) were examined using Wilcoxon rank-sum tests and were also stratified by a number of patient characteristics found to differ between the 2 groups. RESULTS: A total of 1,236 patients met all study entry criteria and were included in these analyses. One or more upward dose adjustments were experienced by 61.7% (N=762) of patients during an average of 15 months of follow-up (median =13 months, range=6 to 31 months). The majority (63.3%) of upward dose adjustments were due to increases in the number of billed vials. Median time to upward dose adjustment was 254 days and declined steadily based on year of initiation (from 330 days in 2000 to 224 days in 2002). Factors significantly influencing upward dose adjustment included pretreatment use of leflunomide, comorbid Crohn.s disease, and pretreatment liver function testing. During followup, patients in the upward dose adjustment group used a mean (SD) of 30.28 (20.90) vials of infliximab, compared with 15.90 (14.28) among those not adjusting dose (P<0.001). Annualized (i.e., standardized to a 365-day rate) RA-related costs were higher by more than 50% among patients with upward dose adjustment (SD $22,283 [$20,517] versus $14,425 [$10,828] for those without upward dose adjustment; P<0.001); differences were driven almost entirely by the costs of infliximab itself ($16,336 [$9,490] versus $9,573 [$6,790], P<0.001). CONCLUSIONS: In a cohort of managed care members with RA, upward dose adjustment with infliximab was frequent and appeared to occur earlier in the drug therapy in 2002 compared with 2000. Upward dose adjustment was associated with significant increases in drug treatment costs; therefore, payers and providers should consider the impact of current dosing trends when monitoring the use of biologics for autoimmune diseases.