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Body mass index and persistence of conventional DMARDs and TNF inhibitors in rheumatoid arthritis

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McCulley CB1, Barton JL2, Cannon GW3, Sauer BC3, Teng CC3, George MD4, Caplan L5, England BR6, Mikuls TR6, Baker JF7. Clin Exp Rheumatol. 2018 Nov 7. [Epub ahead of print]

Abstract

Author information 1 VA Portland Health Care System; Oregon Health & Science University, OR, USA. caroline.bonafede@gmail.com. 2 VA Portland Health Care System; Oregon Health & Science University, OR, USA. 3 VA Salt Lake City Healthcare System; University of Utah; Salt Lake City VA Medical Center (IDEAS 2.0) University of Utah, Division of Epidemiology, Team VERITAS, OR, USA. 4 Division of Rheumatology, University of Pennsylvania, Philadelphia, PA, USA. 5 Department of Medicine, Rocky Mountain VA Medical Center, Aurora, CO, USA. 6 VA Nebraska-Western Iowa Health Care Center and the University of Nebraska Medical Center, Omaha, NE, USA. 7 Division of Rheumatology, University of Pennsylvania, Philadelphia, and Corporal Michael C. Crescenz VA Medical Center, Philadelphia, PA, USA.

Abstract OBJECTIVES: Obese patients with rheumatoid arthritis (RA) may be more likely to discontinue therapy than non-obese patients, possibly signifying a more refractory phenotype. The purpose of this study was to examine the association between body mass index (BMI) and discontinuation rates for different RA treatments accounting for confounding factors.

METHODS: Veterans Affairs administrative databases were used to define initial courses of methotrexate (MTX), hydroxychloroquine, sulfasalazine, prednisone, and self-injectable tumour necrosis factor inhibitors (TNFi). Discontinuation was defined as a lapse in drug refill >90 days. Using overweight BMI (25-30 kg/m2) as the referent group, multivariable Cox proportional hazards models were used to evaluate associations between BMI category and time to treatment discontinuation.

RESULTS: There were 46,970 initial RA treatment courses identified from 2005-2014 among 23,669 Veterans with RA. In multivariable models, severe obesity (BMI >35 kg/m2), compared to overweight BMI, was not associated with treatment discontinuation with the exception of prednisone [HR 1.10 (1.04, 1.17) p<0.001]. Patients with low (<20 kg/m2) and normal BMI (20-25 kg/m2) were more likely to discontinue MTX, TNFi, and HCQ compared to overweight patients. Other factors associated with earlier MTX and/or TNFi discontinuation included female sex, black race, greater comorbidity, depression, malignancy, congestive heart failure, current smoking, and more recent calendar year.

CONCLUSIONS: Obesity was not associated with therapy discontinuation among veterans with RA after accounting for confounding factors, suggesting that obesity is not a biological mediator of more refractory disease. Conversely, low BMI, comorbidity, and depression were identified as important predictors of drug discontinuation.