Abstract
BackgroundTo determine whether initiation of a tumor necrosis factor inhibitor (TNFi) or methotrexate improves hemoglobin A1c in patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), or ankylosing spondylitis (AS) who also have diabetes mellitus (DM).MethodsA retrospective cohort study was conducted in Optum’s de-identified Clinformatics® Data Mart Database, an administrative claims database, using data from 2000 to 2014. Patients with PsA, RA, or AS, with DM (defined by ICD-9-CM codes) and/or HbA1c ≥7%, who newly initiated either a TNFi, MTX, or metformin (positive control) were identified. The change in HbA1c after drug initiation was calculated. Statistical differences in the change in HbA1c between drugs were assessed using the Wilcoxon rank sum test and linear regression models adjusting for potential confounders.ResultsAmong 10,389 drug initiations in 9541 patients with PsA, RA, or AS, and available HbA1c values, HbA1c was ≥7 at baseline in 254 (35%) TNFi initiations, 361(37%) MTX initiations, and 2144 (50%) metformin initiations. Median HbA1c change was − 0.35 (IQR -1.10, 0.30) after TNFi initiation, − 0.40 (IQR -1.20, 0.30) after MTX initiation, and − 0.80 (IQR -1.60, − 0.10) after metformin initiation. In adjusted analyses, TNFi initiators had less of a decrease in HbA1c compared to MTX initiators (β 0.22, 95% CI: 0.004, 0.43), p = 0.046. Metformin initiators had a significantly greater decrease in HbA1c than MTX, β − 0.38 (95% CI: − 0.52, − 0.23), p < 0.001. Glucocorticoid use was not accounted for in the models.ConclusionHbA1c decreased with TNFi initiation or MTX initiation. Reductions in HbA1c after initiation of a TNFi or MTX are about half (~ 0.4 units) the decrease observed after initiation of metformin.
Highlights
To determine whether initiation of a tumor necrosis factor inhibitor (TNFi) or methotrexate improves hemoglobin A1c in patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), or ankylosing spondylitis (AS) who have diabetes mellitus (DM)
More patients in the elevated Hemoglobin A1c (HbA1c) group were on diabetes medications in the baseline period than those in the DM criteria cohort (TNFi 91% vs 76%, MTX 88% vs 72%)
Neither of the sensitivity analyses significantly changed the results. In this retrospective cohort study in patients with DM and inflammatory arthritis, we found that, among patients with an elevated HbA1c at baseline, patients treated with TNFi and MTX had, on average, a small decrease in HbA1c that was approximately half of that seen with metformin initiation
Summary
To determine whether initiation of a tumor necrosis factor inhibitor (TNFi) or methotrexate improves hemoglobin A1c in patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), or ankylosing spondylitis (AS) who have diabetes mellitus (DM). Tumor necrosis factor (TNF)-α, an inflammatory cytokine, is a key player in the pathogenesis of RA, PsA, AS,. In type II diabetes, a chronic inflammatory state exists, marked by increased cytokines such as TNFα, IL-1, and IL-6 [12]. Patients with inflammatory arthritis were found to have greater insulin resistance compared to controls, and this was true for PsA [13]. Another study suggested that infliximab treatment in RA and AS patients may improve insulin sensitivity in patients with high insulin resistance [22]. This study did not compare TNFi use to other common DMARDs
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