Sleep Apnea May Boost Gout Risk

Diana Phillips

October 22, 2015

Sleep apnea appears to be a significant risk factor for the development of incident gout, a population-based study has shown.

The risk of developing gout was up to 60% higher among patients with sleep apnea vs individuals without sleep apnea, Yuqing Zhang, MD, DSc, from the Boston University Clinical Epidemiology Research and Training Unit and the Department of Medicine at Boston Medical Center in Massachusetts, and colleagues write. They report their findings online October 19 in Arthritis & Rheumatology.

Using data from the Health Improvement Network in the United Kingdom, the investigators identified 9865 patients newly diagnosed with sleep apnea between 2000 and 2013. They matched each patient with up to five individuals (43,598 total) without sleep apnea based on sex, age, birth year, and body mass index.

During the 1-year follow-up period, 76 patients with apnea were newly diagnosed with gout compared with 194 of those in the control group. The median age at the time of gout diagnosis was 60 years (range, 25 - 86 years). The incidence rates of gout in the apnea and comparison cohorts, respectively, were 8.4 and 4.8 per 1000 person-years.

Compared with those in the control group, the crude rate ratio for incident gout among those with sleep apnea was 1.7 (95% confidence interval [CI], 1.3 - 2.2). The authors note that adjusting for potential confounders, including alcohol consumption, comorbidities, medication use, and the number of general practitioner visits, did not substantially change the effect estimate.

The crude rate difference of incident gout between the sleep apnea and comparison cohorts was 3.6 (95% CI, 1.6 - 5.6) per 1000 person-years, and the adjusted rate difference was 2.8 (95% CI, 0.7 - 4.9) per 1000 person-years, the authors write. The increased risk for incident gout from sleep apnea persisted across subgroups by sex, age, and obesity status.

"The observed increased risk of gout was 60% higher among patients with sleep apnea in ratio scale, as compared with individuals who were at a very high risk of developing gout (4.8 per 1000 person-years) with a high [body mass index] level (mean, 32.2 kg/m2), whereas the absolute difference in the incidence rate of gout was approximately 3 cases per 1000 person-years. Such a risk is much higher than that reported in other studies," the authors write.

One of the possible biological mechanisms for the association between sleep apnea and gout risk is apnea-induced hypoxia, which can promote nucleotide turnover, generating purines that are metabolized to uric acid, the authors suggest. In addition, previous studies have demonstrated a higher prevalence of hyperuricemia among patients with sleep apnea.

Because sleep apnea–associated hypoxia is treatable (eg, with noninvasive ventilation continuous positive airway pressure), "our findings may have both important clinical and public health implications in the prevention and management of gout," the authors write. The findings point to the need for additional research to examine the potential benefits of correcting sleep apnea–induced hypoxia on the risk for hyperuricemia and gout flares, the authors conclude.

The authors have disclosed no relevant financial relationships.

Arthritis Rheumatol. Published online October 19, 2015. Abstract

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