Gout is a risk factor for the development of chronic kidney disease (CKD) stage 3 or higher, UK investigators concluded.
In a retrospective cohort study that matched 41,446 new gout cases to the same number of patients without gout, Matthew J. Roughley, MBChB, of the East London NHS Foundation Trust, and colleagues found that CKD stage 3 or higher developed in 6694 patients with gout (16.2%) and 3953 patients without gout (9.5%) during a median follow-up period of 6 years.
The absolute rate of CKD stage 3 or higher (per 10,000 person-years) was 28.6 in the gout group compared with 15.8 in the no-gout group, according to findings published in Arthritis Research & Therapy. After adjusting for age, gender, comorbidities, and other variables, gout was associated with a significant 78% increased risk of CKD stage 3 or higher.
Treatment with urate-lowering therapy had no significant effect on CKD development in adjusted analyses.
The investigators ascertained development of CKD stage 3 or higher based on 2 consecutive measures of an estimated glomerular filtration rate of less than 60 mL/min/1.73 m2 at least 3 months apart.
A baseline, patients had a mean age of 57 years, and 81% were male. Compared with the no-gout group, patients with gout had a higher prevalence of diabetes mellitus (6.5% vs 5.8%), treated hypertension (28.9% vs 16%), and obesity (36.9% vs 20.3%).
“Whilst it is not possible to make causal inferences from this observational study,” Dr Roughley’s team wrote, “it is worth considering the potential plausible mechanisms for the association between gout and CKD. Renal damage could result from comorbid hypertension, diabetes mellitus, obesity or use of nonsteroidal anti-inflammatory drugs.”
With regard to study strengths, the investigators noted that patients were selected from primary care settings where most patients with gout are managed, which would aid generalizability. “The sample size was large and the median follow-up was 6 years, which should be sufficient for development and ascertainment of CKD stage ≥3.”
The authors acknowledged that ascertainment bias is a possible study limitation because patients with gout presented more frequently to general practitioners and hospitals and had a higher prevalence of hypertension and diabetes, “which could have prompted more renal function testing.”
Roughley M, Sultan AA, Clarson L, et al. Risk of chronic kidney disease in patients with gout and the impact of urate lowering therapy: a population-based cohort study. Arthritis Res Ther. 2018;20:243. doi: 10.1186/s13075-018-1746-1