Background Rheumatoid arthritis (RA) is characterized by an increased cardiovascular diseases (CVD) risk, estimated to be about 50% greater when compared to the general population. Insulin resistance (IR), a key feature of the Metabolic Syndrome (MS) represents a well-recognized independent cardiovascular risk factor. RA has been epidemiologically correlated with an elevated prevalence of MS independently of corticosteroids exposure, and the coexistence of RA with MS appears to be associated with a higher disease activity.
Objectives Aim of this work was to examine the correlation between measures of inflammation and IR in RA patients.
Methods Height, weight and waist circumference (WC) were measured and Body Mass Index (BMI) was calculated with the standard formula. DAS28-CRP was used to evaluate disease activity. After overnight fasting, blood samples were obtained for laboratory evaluation including: complete blood count, plasma glucose, insulin, ferritin, erythrocyte sedimentation rate (ESR), High Sensitivity-CRP. Insulin resistance was estimated with the indirect measure Homeostasis Model Assessment of Insulin Resistance (HOMA-IR). Paired samples Student's t-test was used to compare means. The Pearson product-moment correlation coefficient was used to evaluate correlation between variables. Continuous variables that were not normally distributed were ln-transformed before analysis. A p-value <0.05 was considered statistically significant.
Results For the present study 100 RA patients (44 males, 56 females) and 100 age- and sex matched controls were recruited. Patients tended to be overweight and with a higher waist circumference compared to controls. In univariate correlational analysis HOMA-IR correlated significantly with age (r=0.34, p=0.001), BMI (r=0.69, p<0.0001), WC (r=0.66, p<0.0001), DAS28-CRP (r=0.25, p 0.02), ln(hs-CRP) (r=0.39, p=0.0002), ESR (r=0.43, p<0.0001), complement C3 (r=0.36, p=0.0006) and ln(Ferritin) (r=0.26, p=0.01). In controls, HOMA-IR correlated only with measures of obesity but not with inflammatory markers.
Conclusions In the present study we demonstrated that in RA patients, but not in controls, the indirect measure of insulin resistance HOMA-IR correlates with measures of inflammations. In this context, ESR is the single best parameter reflecting insulin resistance.
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Disclosure of Interest None declared