Assessment of pain severity and functional status in patients with knee osteoarthritis at the Kenyatta National Hospital , Nairobi, Kenya

Abstract

Background: Chronic pain in knee osteoarthritis influences the quality of life and functional status of these patients. Despite numerous  treatment modalities, pain may be inadequately controlled and affect a patient’s functional status. This may be more evident in our local  setup as patients tend to present later in the disease. This study was designed to understand the burden of pain in knee osteoarthritis.

Objective: To assess pain severity and the level of function in patients with knee osteoarthritis at the Orthopedic and Rheumatology  clinics at the Kenyatta National Hospital (KNH).

Methods: A cross-sectional descriptive study that assessed patients above the age of 18  years with a diagnosis of knee osteoarthritis on follow-up who fit the inclusion criteria. The pain was assessed by the Brief Pain Inventory- Short Form (BPI-SF) and the functional status was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index  (WOMAC). Pain severity was analyzed and presented as a proportion of patients having either mild, moderate, or severe pain. Any patient reporting a pain score >4 in question 5 of BPI-SF indicating moderate (4-7) or severe pain (>8) was classified as having inadequate pain  control. Functional impairment was assessed using the WOMAC score (0-96). A higher score indicated poorer function. Pain severity was  associated with functional status using the ANOVA test. The chi-squared test was used to associate patient-related factors with pain  control. A 5% level of significance was used to interpret all the statistical tests (p-value less or equal to 0.05).

Results: A total of 270  patients were recruited into the study of whom 139 (51.5%) were females and 131 (48.5%) were males, The mean age of the study  population was 55.1 years. The majority of the patients were overweight (n= 134, 49.6%) with a smaller number (n=27, 10%) being obese. The median duration of osteoarthritis diagnosis was 48 months. Bilateral knee osteoarthritis (n= 172, 63.7%) was more prevalent than  unilateral disease (n= 98, 36.3%). Knee pain was inadequately controlled in 265 (98.1%) participants with these patients scoring >4  (moderate to severe pain) in Question no 5 (pain on average) of the BPI-SF. The majority of participants (n=259, 95.9%) also had  functional impairment/disability. Participants with inadequate pain control (moderate pain or higher) had a worse functional status  p-0.026 (<0.05). Older patients had higher pain severity p-0.029 (<0.05).

Conclusion: Pain severity is mostly moderate or severe indicating  poor pain control in patients with knee osteoarthritis. Higher pain severity is more common in older patients and is associated with worse  functional status. This limits their daily activities and enjoyment of life.