ABSTRACT
There are few studies about the relationship between platelet indices and the activity of rheumatoid disease and it is still a controversial issue. Therefore we decided to study the relationship between platelet indices and severity of rheumatoid arthritis according to DAS28 criteria. In this Historical cohort study, 250 patients with rheumatoid arthritis and 250 people who accompanied the patients were selected via convenient sampling method. After written consent; 2cc of blood was taken from each patient and was sent to our laboratory. All patients were examined by a rheumatologist for diagnosis of disease activity. DAS28 formula was used to evaluate the severity of disease activity. Data were entered into SPSS 16 software and analyzed by independent t-test, Pearson correlation and multiple regression analysis. The mean values of hemoglobin [p<0.001], hematocrit [p<0.001], MCH [p<0.001], and PLcr [p=0.002] were lower in the patient group compared to the control group. The mean values of platelet [p<0.001], RDW [p=0.001], and PDW [p= 0.03] were higher in the patient group in comparison to the control group. There was no statistically significant differences between the two groups in relation to the mean values of MCV [p= 0.22] and MPV [p= 0.21]. A significant negative correlation was observed between DAS28 scores of hemoglobin [p=0.005] and hematocrit [p=0.02]. Increased severity of the rheumatoid arthritis led to decreased hemoglobin and hematocrit and increased platelet count. Therefore, these blood parameters can be used as a primary prognostic factor. Also ESR can be regarded as a good prognostic factor. However, MCV and MPV are not suitable prognostic factors for the patients with rheumatoid arthritis