Platelet counts in patients with rheumatoid arthritis at the Kenyatta National Hospital Afri J Rheumatol

Abstract

Background: Rheumatoid arthritis (RA) is a disease associated with significant morbidity and mortality. Thrombocytosis is one of the haematological manifestations of rheumatoid arthritis that occurs in active disease. Platelet counts may vary depending on disease activity and the variation has been shown to correlate with clinical and laboratory indices of disease activity in RA. Occasionally patients with RA may have drug induced thrombocytopenia. Objectives: To determine the relationship between platelet counts and clinical disease activity in patients with RA at Kenyatta National Hospital (KNH). Design: A cross-sectional descriptive study. Setting: Rheumatoid arthritis patients attending the KNH Rheumatology Outpatient Clinic (ROPC). Methods: Patients presenting to the clinic were screened and those meeting the inclusion criteria recruited into the study. Consecutive sampling technique was done. A targeted history was obtained, following which a physical exam was done on the recruited patients. The patients’ platelet counts were measured using Abbot Cell Dyn 1300. The patents’ erythrocyte sedimentation rate (ESR)) was measured with the Wintrobe’s method. The patients’ clinical disease activity using the DAS 28 score was recorded. Results: One hundred and four patients were recruited over the 6 months period between November 2010 and April 2011. Females were 90(86.5%) and 14(13.5%) were males giving a male to female ratio of 1:6.4. The mean age of the patients was 48 years. Regarding medication use, 75% of the patients were on disease modifying anti-rheumatic drugs (DMARDs), 72.1% on non-steroidal analgesics (NSAIDs) and 46.2% on steroids. The mean platelet count was 313.2 ±SD94 x 10/L with a range of 152 -611 x 10/L. Only 15 (14.4%) had thrombocytosis (>400x 10/L). No case of thrombocytopenia was recorded. Ninety two had active disease (88.5%) while 10(11.5%) were in remission. Among those with active disease,10(9.6%) had mild disease, 51(49%) moderate disease and 31(29.6%) high disease activity. The DAS28 score was not significantly different between those who had thrombocytosis and those who had normal platelet counts (p=0.413). However, HB, MCV and MCH were significantly lower in those with thrombocytosis at P values of 0.02, 0.002, 0.03 respectively. No correlation was found between platelet counts and clinical disease activity (DAS28). Conclusion: While thrombocytosis was found in 14.4% of patients with RA, this study demonstrated that no relationship exists between platelet counts and dis-ease activity in patients with rheumatoid arthritis seen at KNH