Objectives To describe insulin resistance (IR) in patients with rheumatoid arthritis (RA) and compare it with healthy controls and to analyze the association between the accumulated inflammatory burden in patients with RA and IR.
Methods Design: Observational case-control study. Population: consecutive RA-patients (ACR/EULAR 2010 criteria), >16 years, selected from a prospective inception cohort (diagnosis of RA between 2007 and 2011). Patients with Diabetes Mellitus (according to ADA 2010 criteria) were excluded. Controls: sex- age and BMI -matched controls were collected from a health center in our hospital area. Protocol: Cases and controls were evaluated by a rheumatologist. Clinical data of disease activity (RA patients), analytical values and oral glucose tolerance test (OGTT) were determined. All participants signed informed consent. Main outcome: IR measured by the homeostasis model for insulin resistance (HOMA-IR) (IR>2.29 μU * mmol/ml). Secondary outcome: IR measured by quantitative insulin sensitivity check index (QUICKI) (<0.337μU * mmol/ml) and by the homeostatic model assessment of β-cell function (HOMAβ). Variables: Demographic, clinical-analytical variables, Disease Activity Score of 28 joints (DAS28-ESR), Health Assessment Questionnaire (HAQ), BMI (according to OMS classification) and glucose and insulin before and after OGTT values. Statistical analysis: Descriptive and paired T-test or Chi-square test followed by binary logistic regression in RA patients (Dependent variable: Insulin Resistance).
Results Sixty-two subjects were studied, 8 of them were excluded after OGTT (4 diabetic patients and their respective controls). Finally, 54 subjects were included; 27 RA and 27 healthy controls. The mean age of patients with RA was 52.2 (12.1) years. Most of them were women (88.9%), with seropositive (FR 81.5% and ACPA 74.1%) and erosive (63%) RA. The mean duration of the disease was 85.6 months (27.1) and mean DAS 28 index since the onset of the disease of 2.98 (0.9).
Differences between clinical characteristics and in relation to IR between cases and controls are shown in Table 1. No significant differences in the proportion of subjects with IR in cases and controls were observed. 33.3% of patients with RA had IR. In multivariate analysis, the only independent variable associated with IR in RA patients was disease activity score (DAS28) (OR [95% CI] = 3.6 [1.0–12.9], p=0.045).
Conclusions The only predictor of IR in RA patients was the inflammatory activity measured by DAS28. We did not find a higher IR in RA patients than in healthy controls, it could be because the patients were well treated and the inflammatory activity was controlled in the most of them.
Disclosure of Interest None declared