The Effect of Spironolactone on Pain in Older People With Osteoarthritis

This pilot study will obtain preliminary evidence on which to base sample size calculations for a future trial of whether spironolactone (an aldosterone blocker) reduces knee pain in older people with symptomatic OA knee when given in addition to usual analgesia. Aldosterone is known to be pro-inflammatory, and spironolactone suppresses cytokine production in chronic arthritis. This application builds on previous work by the applicants showing that spironolactone significantly improved quality of life (particularly pain) in frail older people. The investigators will recruit 86 people (aged 70 years or over) with well-defined OA knee to 25mg spironolactone daily or to matching placebo for 12 weeks. The primary outcome is the between group difference in change in WOMAC pain sub-score at 12 weeks. Secondary outcomes are the WOMAC stiffness and physical function subscales and health related quality of life (EQ-5D). Morning cortisol levels will be measured to assess the effect of mineralocorticoid receptor blockade on glucocorticoid levels, which may mediate the anti-inflammatory effect of spironolactone; and urinary CTX-II, and serum matrix metalloproteinase-3 (MMP-3) will be measured as biomarkers as both are sensitive to the effects of pharmacological interventions for osteoarthritis.