Gout or gouty arthritis is a common and painful inflammatory arthritis characterised by deposition of monosodium urate crystals in joint fluid and articular tissue. Gout affected over 7.5 million Americans during 2009–2010.
The probability of developing gout can depend not only on urate load but also on other risk factors such as older age, obesity, male sex, female menopause, hyperuricaemia, hypertension, chronic kidney disease (CKD), excessive purine-rich diet and excessive alcohol consumption
To assess the role of CKD as an independent risk factor for developing incident gout, in the study titled “Chronic kidney disease as a risk factor for incident gout among men and women: retrospective cohort study using data from the Framingham Heart Study”, Weiqi Wang from Stanford University School of Medicine and colleagues, assessed a total of 2,558 women and 2,159 men who were enrolled in the Framingham Heart Study (FHS). Study participants were sought from the National Heart, Lung, and Blood Institute (NHLBI) from 1948 to 2002. Importantly, researchers excluded from their primary analysis all patients that at baseline had a diagnosis of chronic kidney disease (CKD) or gout.
Patients were followed biennially (the mean age at entry to the cohort was 45 years) and patient’s data were collected, included BMI, smoking status and presence of diabetes or hypertension. The median follow-up time was of 36 years.
Gout was identified through patient’s records, including a physician’s diagnosis of gout or the use of a gout medication (allopurinol, probenecid or colchicine), and CKD was identified by a physician’s diagnosis. Serum uric acid (SUA) was measured at visits 1, 2, 3, 4 and 13; estimated glomerular filtration rate (eGFR) was available for five visits, and serum creatinine levels were available sporadically.
Results revealed that there were 371 incident cases (231 men and 140 women) of gout over the follow-up of 140 421 person-years. The rates of gout incidence per 1,000 person-years for participants with and without CKD were of 6.82 and 2.43, respectively. Results from the multivariable Cox models showed that CKD was associated with gout, with a HR of 1.88 among men and 2.31 among women. Additional analyses using alternate definitions for CKD and cross-sectional study did not change the results.
According to the researchers, these prospective data from the FHS provide the empiric basis that CKD is a risk factor for gout and the temporality of the association points towards an underlying causal nature.