FRI0057 INSULIN RESISTANCE IN ELDERLY ONSET RHEUMATOID ARTHRITIS AND POLYMYALGIA RHEUMATICA

Abstract

Background: Rheumatoid arthritis (RA) patients have a higher insulin resistance (IR) and some studies report that it is present at diagnosis. Systemic inflammation has been pointed out as the reason. However, data on polymyalgia rheumatica (PMR) are controversial. Objectives: To analyse IR in a group of untreated patients with a recent diagnosis of RA and PMR, and to establish predictive factors related with IR. Methods: Longitudinal observational study of patients older than 60 years, newly diagnosed with elderly-onset AR (ACR/EULAR 2010) and PMR (ACR/EULAR 2012). Comparison with healthy control group of the same age. Inclusion: consecutive and voluntary. Exclusion: patients with insulindependent diabetes. Follow-up time: 12 months. The clinical-epidemiological, anthropometric and analytical characteristics were collected. IR was calculated by HOMA-IR [(homeostatic model assessment of insulin resistance) = glucose (mg/dL) ∗ insulin (mUI/L)/405] baseline and at 12 months. HOMA-IR>2.75 was considered IR (according to Spanish data). The statistical study was performed with Stata 15.1. Results: We recruited 42 patients with RA, 18 with PMR and 18 healthy controls. None of them had received treatment with corticosteroids or with DMARD at the baseline visit. Baseline characteristics are summarized in the table. RA (N=42) PMR (N=18) P value Epidemiological data Women n (%) 18 (42.9) 15 (83.3) 0.001 Age (mean ± s) 74.4 ± 7.6 76.4 ± 5.2 0.594 Diabetes mellitus 15 (35.7) 3 (16.7) 0.140 BMI (kg/m2) 27.7 [25.1-30.5] 26.5 [24.0-29.1] 0.393 Abdominal perimeter (cm) 100 [95-106] 94 [90-104] 0.076 Analytical data Glycohemoglobin% 6.1 [5.9-6.4] 5.8 [5.6-6.5] 0.107 ESR (mm/1hora) 49 [36-75] 52 [42-69] 0.508 CPR (mg/L) 24.4 [7.1-44.1] 22.1 [12.4-45.9] 0.670 RF positive n (%) 14 (33.3) 1 (5.6) 0.023 ACPA positive n (%) 13 (30.9) 2 (11.1) 0.104 RF and ACPA positive n (%) 17 (40.5) 3 (16.7) 0.073 Insulin resistance test HOMA-IR median[RIQ] 3.6 [2.1-5] 2.1 [1.6-3.4] 0.004 At baseline visit, 66.7% of patients with elderly-onset RA had IR, compared with 33.3% of controls (p=0.024) and 27.8% of PMR (p=0.006). Therefore, the prevalence of IR in patients with RA doubled that of controls and patients with PMR before starting treatment. After 12 months of evolution and treatment, patients with RA and IR decreased from 66.7% to 51.2%, not being statistically significant (p=0.179). On the other hand, the percentage of patients with PMR and IR remained the same (27.8%). The differences in IR between RA and PMR at 12 months remained statistically significant (p=0.048). Given the results we decided to analyze the predictive factors related with IR only in the 42 patients with RA. In the univariate logistic regression analysis, the predictors of presenting IR were the BMI, the abdominal perimeter and the scapular girdle involvement. Specifically for BMI, for each of 2 kg/m2 the probability of having IR was 1.24 times higher (OR=1.24, IC95%: 1.12-1.37). Patients with scapular girdle involvement had a 6-fold increased risk of developing IR (OR = 6.0, 95% CI: 1.3-26.6). And for every 5 centimetres of abdominal perimeter the risk increased almost 4 times more (OR=3.9, 95% CI: 2.9-5.1). In the multivariate analysis, the only independent factor to increase the IR was the abdominal perimeter (aOR = 1.23, IC95%: 1.07-1.41). Conclusion: Patients with elderly-onset RA have a higher IR than the general population. High IR in RA is present at diagnosis. IR in AR is not exclusively mediated by systemic inflammation, since patients with PMR do not have this increase. The predictors of presenting IR in late onset AR were BMI, scapular girdle involvement and abdominal perimeter. Only the abdominal perimeter was shown as an independent factor.