Clinical Predictors of the Response to Glucosamine in Chronic Knee Pain

Abstract

PURPOSE: To identify clinical features that predict response to treatment with glucosamine sulphate in individuals with chronic knee pain. The specific hypothesis is that age, body mass index, absence or presence of osteoarthritis and severity of osteoarhritis, predict response to glucosamine sulphate. METHODS: A prospective correlation study of pre- and post intervention was perfomed. A cohort of 45 patients with chronic knee pain were recruited and treated with 12 weeks of oral glucosamine sulphate 1.5g daily. Subjects underwent assessment at baseline and after completion of treatment. Baseline knee radiographs were used to assess presence and severity of osteo arthritis (OA). Primary outcome measures used to determine clinical response to glucosamine were the Visual Analogue Scale (VAS) for pain and function and the Knee Osteo arthritis Outcome Scale (KOOS). Secondary outcome measures were the Patient global change score and Patient Specific Functional Score. Statistical analysis was performed to confirm response and logistic regression analysis was used to identify predictor variables. RESULTS: Sixteen (35.6%) male and 29 (64.4%) female patients with a mean duration of symptoms of 9.5yrs (range 0.5–45) were included in the study. The mean age was 52.7yr (range 31–82) and BMI was 27.8kg/m2 (range 19.1–38.4). Thirty-eight (63.6%) had American College of Rheumatology denned OA. Severity of OA was determined by Kellgren and Lawrence grading: Gade I-9%, Grade II-9%, Grade 3–14%, Grade 4–16%. There were significant improvements in all primary and secondary outcome measures including VAS for pain on movement (p=0.002), VAS for pain at rest (p= 0.009), VAS for restriction in daily activites (p<0.001) and VAS for pain on worst activity (p<0.001). Four predictor variables; presence and absence of osteophytes, severity of OA, age and BMI were analysed by logistic regression with response to primary outcome measures. Presence of osteophytes (p=0.04) and more mild osteoarthritis (p=0.048) predicted improvement in restriction in activities of daily living as measured by VAS. However none of these clinical variables predicted response to any other outcome measure. CONCLUSIONS: Glucosamine sulphate 1.5g daily resulted in a significant improvement in all outcome measures in a population of patients with chronic knee pain. The presence of OA and milder OA are predictors of improvement in restriction in activities of daily living. However, response to all other outcome measures including, pain, other symptoms, sport and recreation and quality of live, are equal in patients with chronic knee pain regardless of age, BMI, presence or absence of OA and severity of OA.