Gout Patients Face a Higher Risk for Advanced Kidney Disease

Gout patients who respond successfully to urate lowering therapy have higher rates of chronic kidney disease improvement, a study presented on Nov. 13 at American College of Rheumatology annual meeting shows.

The study, presented by Gerald Levy of Southern California Kaiser Permanente, is featured in Arthritis & Rheumatology and shows that lowering serum urate levels to less than 6mg/dl utilizing urate lowering therapy produces more robust improvement in kidney function in the form of more than 30% increases in glomerular filtration rate. This improvement is seen in all stages of chronic kidney failure and the urate lowering effect is most pronounced in stage 3-kidney disease.

Chronic kidney disease is an important cause of morbidity in patients with elevated uric acid levels and the effect of achieving American College of Rheumatologists goal of serum uric acid levels less than 6mg/dl has not been described.

The authors performed a retrospective cohort study and included patients with a serum uric acid level greater than 7mg/dL that had estimated glomerular filtration rate determination within the six months preceding the index date. Furthermore, patients could not have been on urate lowering therapy prior to enrollment. Primary outcomes consisted of either a 30% increase or reduction in glomerular filtration rate.

12,751 patients were enrolled with 2,690 starting urate lowering therapy and 10,061 not receiving urate-lowering therapy. 42% of patients put on urate lowering therapy reached serum urate levels less than 6mg/dL and subsequently 17.1 % of those patients saw a 30% increase in estimated glomerular filtration rate while only 10.4% of those not reaching the goal saw corresponding increases in glomerular filtration. (95% CI= 4.0-9.4, p< .001) When pairwise comparison was applied to kidney disease staging the results show patients at or below goal urate levels achieved 30% increases in glomerular filtration rates in the following numbers:  Stage 2: 7.1% to 3.3% for those not reaching serum urate goal (95% CI= 0.7-7.0, p= .015), Stage 3: 19.9% to 10% (95% CI= 6.1-13.6, p< .001), and Stage 4: 30% to 22.2% (95% CI -1.1-16.8, p= 0.080).

Gout is Associated with an Increased Risk of Advanced Chronic Kidney Disease

A related British study presented on Nov. 16 at ACR 2016 shows that patients with gout experienced significantly higher risk of advanced chronic kidney disease as compared to patients without gout.

Utilizing the UK Clinical Practice Research Datalink database, a cohort study of adult patients with gout was conducted based on records between January 2000 and March 2013. A total of 68,897 gout patients and 554,964 controls were enrolled. The patients were prescribed urate lowering therapy and each adult case was matched with up to 10 controls without gout. The median follow-up was 3.68 years.

The composite outcome was defined as need for dialysis, renal transplant, stage five kidney disease, estimated glomerular filtration rate less than 10ml/min, death with kidney disease or doubling of serum creatinine.

When patient differences were accounted for, the authors found that patients with gout were at higher risk of high-grade chronic kidney disease than those without gout (hazard ratio with gout 1.29 95% CI 1.23-1.35: hazard ratio without 1.00). When propensity matching was employed the results did not change significantly (hazard ratio 1.23, 95% CI 1.17-1.29).

Disclosures:

The authors of "Association of Gout with Risk of Advanced Chronic Kidney Disease" disclosed a number of pharmaceutical company-related conflicts of interest.

References:

Gerald D. Levy. "Urate Lowering Therapy in Moderate to Severe Chronic Kidney Disease," Abstract number 912. 11:45 a.m., Nov. 13, 2016. ACR/ARHP 2016 Annual Meeting. 

Austin Stack. "Association of Gout with Risk of Advanced Chronic Kidney Disease," Abstract number 3188. 11:45 a.m., Nov. 16, 2016. ACR/ARHP 2016 Annual Meeting.