Gout is the most common cause of inflamed joints and occurs when levels of uric acid in the blood get so high that tiny uric acid crystals form inside joints. Erectile dysfunction (difficulty obtaining and maintaining an erection) is also a common problem, particularly in older men. Men with gout and erectile dysfunction very commonly have other medical problems such as high blood pressure, heart disease and being overweight, and both conditions are more common in people who drink alcohol excessively. It seems likely therefore that gout and erectile dysfunction should commonly occur together. In this study, we will examine whether men who have gout are more likely to develop erectile dysfunction than men who do not have gout.
The objective of this study is to determine whether there is a potentially causal association between the diagnosis of gout and the subsequent development of erectile dysfunction. The study design is a matched cohort study. Men with a new diagnosis of gout will be matched (1:4) on year of birth and general practice to men without gout up to the date of their matched gout patient's diagnosis. Patients with and without gout will also be free of a diagnosis of erectile dysfunction and not prescribed medication for this condition prior to this date. The outcome of interest will be a diagnosis of incident erectile dysfunction. A feasibility count in CPRD suggests that there are 49,462 men with an incident diagnosis of gout and no pre-existing diagnosis of or treatment for erectile dysfunction from 01/01/1990 to 31/12/2010. Assuming that 8% of men without gout consult for erectile dysfunction over a 10-year period, this sample size provides 98% power detect a hazard ratio of 1.2. Cox regression models will be used to assess the association between gout status (exposure) and time to diagnosis of erectile dysfunction, adjusted for confounding comorbid conditions and prescriptions.