Evaluation of adverse drug reactions in patients with Rheumatoid Arthritis in the Yaoundé Central Hospital

Elvis NKENG (cenkeng@gmail.com)
Internal Medicine, University of Yaoundé I
June, 2017


Background: Rheumatoid arthritis (RA) is a chronic autoimmune disease which is characterized by chronic inflammatory synovitis and joint erosion. Treatment of RA is based on non-steroidal anti-inflammatory drugs (NSAIDs), steroids and disease modifying antirheumatic drugs (DMARDs). Patients require these treatments all through their life to prevent joint damage and to maintain day to day functioning. However, due to their significant toxicity, these could cause adverse drug reactions (ADRs) which are estimated to be the 7th most common cause of death. Due to the adverse effects caused by these drugs, coupled to the narrow therapeutic window and the immunosuppressive properties of some drugs used in the treatment of RA and very few publications on the prevalence of ADRs in patients with RA in Cameroon, we proposed to carried out this study to evaluate adverse drug reactions in patients with RA attending the Rheumatology outpatient unit of Yaoundé Central Hospital- Cameroon.
Methods: We carried out a prospective observational study from January 5th 2017 to March 31st 2017 in the Rheumatology outpatient unit. We consecutively recruited participants who filled the ACR/EULAR criteria for RA, who were currently on medications and who filled the inform consent. Using our questionnaire which consisted of the patient’s demographic details, medication details and relevant data of laboratory investigations, patient’s prescriptions were collected and analysed. The medication details collected from the patients included data like name of the prescribed drug or drug combinations, dosage form, daily dosage, frequency, drugs prescribed and all the co-prescribed drugs. A modified version of the Pharmacy and Poisons board yellow form for reporting suspected adverse drug reaction was used. Causality assessment was done by using Naranjo Adverse Drug Reaction Probability Scale scoring system. The severity assessment was done using modified Hartwig and Siegel Severity Assessment scale. The one-way analysis of variance (ANOVA) was used to compare means, proportions were compared using the student t test and all p values < 0.05, considered statistically significant.
Results: A total of 40 people were people were included in the study. Majority (33; 82.5%) of the study population were female. The age groups 51-60 years and 61-70 years each made up 20% of the population. The average number of drugs per prescription was 3.15 with 62.5% on single DMARD, 30.0% on 2 DMARDs and none on 3 DMARDs or biologic agents. About 67.5% were prescribed steroids. A total of 125 adverse drug reactions were reported with an average of 3.1 per patient. The most common ADRs were pruritus and excessive fatigue which accounted for 10.4% of all suspected ADRs. The most affected body systems were the hematological (20.0%), dermatological (20.0%) and neurological (19.2%) body systems respectively. Eighty percent (80%) of ADRs were mild with 42.9% resulting in dose reduction. People aged between 61-70 years had the highest number of ADRs (28.8%).
Conclusions: Treatment of rheumatoid arthritis is based on DMARDs and glucocorticoids where it is difficult to prevent the occurrence of ADR. Our results highlight the high frequency of adverse drug reactions among individuals treated for rheumatoid arthritis. Early initiation of therapy should also be followed by an important detailed counseling and monitoring to maintain treatment adherence.

Keywords: Rheumatoid arthritis, Adverse drug reactions.