The Burden of Fibromyalgia in End-stage Kidney Disease Patients Undergoing Maintenance Haemodialysis – a Multicentre Study

Abstract

Background: Fibromyalgia (FM) is a disease seen in rheumatology and is getting increasingly acknowledged. It presents with chronic widespread pain and specific tender points on clinical examination. The cause is unknown but its aetiopathogenesis is multifactorial. It has several associated symptoms which include fatigue, sleep disorders and depression. These symptoms may remarkably affect the quality of life of affected individuals. The burden of chronic kidney disease (CKD) is increasing in our set up due to an increase in non-communicable diseases (NCDs) such as diabetes and hypertension. The prevalence of fibromyalgia in end stage kidney disease (ESKD) patients undergoing maintenance haemodialysis (HD) in our setting is not known. Objective: The aim of this study was to determine the burden of fibromyalgia in patients with end stage kidney disease patients undergoing maintenance hemodialysis. Materials and Methods: This was a multicenter cross-sectional study that was done at the renal units in Kenyatta National Hospital (KNH), Nairobi Hospital (NH) and the Parkland’s Kidney Center (PKC). The study participants were adults undergoing maintenance hemodialysis and a total of 167 patients were studied. Proportionate random sampling was done to recruit patients from each centre. A written informed consent was obtained. A study proforma that included demographic characteristics and clinical details were administered to patients coming in for maintenance haemodialysis. The diagnosis of fibromyalgia was established using the 1990 American College of Rheumatology criteria. The revised Fibromyalgia Impact Questionnaire (FIQR) was administered to the group of patients with fibromyalgia to evaluate severity of the disease. Quality of life was determined by administering the 36-item short form health survey. Data from the study proforma were assigned unique codes. After data cleaning and validation, data analysis was performed using SPSS version 25.0 with the help of a statistician. Categorical data of the study population such as gender, marital status and level of education are summarized into proportions. Continuous variables such as age, duration of dialysis in months and frequency of dialysis per week are summarized into means, medians and standard deviations. The prevalence of fibromyalgia is presented as a percentage in each center. The severity of fibromyalgia is presented as a proportion in each class (mild, moderate and severe). The quality of life is expressed as a proportion of those with poor quality of life (an average score of less xii than 50%) in individuals with ESKD undergoing maintenance hemodialysis. Statistical differences between QoL in patients with and without fibromyalgia was assessed using the Student t-test. Logistic regression analysis was applied to estimate the probability of being in good health. A P value of ≤0.05 was considered significant for all statistical tests. Results: A total of 167 patients were recruited into the study. The prevalence of fibromyalgia in ESKD patients undergoing haemodialysis in the three centres was 18.0% (n=30). The mean age of these patients was 53.8 with a female preponderance of 66.7% (n=20). The median duration of dialysis was 22 months, and patients with fibromyalgia had dialysed 12 months longer than those without fibromyalgia. A majority of the patients had hypertension and diabetes as the underlying aetiology for development of ESKD. There was however no association between fibromyalgia and underlying aetiology or frequency of dialysis per week. The mean FIQR score was 50.3. The majority of patients diagnosed with fibromyalgia had moderate severity of symptoms. The patients diagnosed with fibromyalgia were six times more likely to have a poorer quality of life than those without fibromyalgia and this was statistically significant (p<0.001). Conclusion: In our study the prevalence of fibromyalgia in CKD was found to be 18%. This is higher than the baseline population prevalence of 1%. Majority of the fibromyalgia patients had mild to moderately severe disease. Patients with fibromyalgia in ESKD on haemodialysis are six times more likely to have a poorer quality of life than those without fibromyalgia in ESKD on haemodialysis.