WASHINGTON -- Patients with hyperuricemia and chronic kidney disease who achieved their serum uric acid target had a significantly greater improvement in estimated glomerular filtration rate (eGFR) than those with persistent elevations of uric acid, a retrospective study found.
"Getting to goal helped prevent progression of renal disease and actually improved renal function in a significant number of people," , of Southern California Kaiser Permanente in Downey, said at a press conference here at the .
Hyperuricemia can lead to the deposition of crystals and in some patients, to chronic kidney disease, and progressive kidney disease leading to dialysis can have an impact on patients on a daily basis, he explained, adding that hyperuricemia represents a major cost to the healthcare system.
A total of 12,751 patients enrolled in the large integrated healthcare delivery system during the years 2008 to 2014 had chronic kidney disease and serum uric acid levels above 7 mg/dL. Of these, 2,690 received urate-lowering therapy, and 42% achieved the target serum uric acid of less than 6 mg/dL.
Patients undergoing active treatment for cancer, who were on dialysis, or who had received a kidney transplant were excluded. At the time of enrollment, participants could not have previously been receiving urate-lowering therapy, and had to have stages 2, 3, or 4 chronic kidney disease. Patients also were required to have had continuous healthcare coverage during the entire period of the study.
Among participants who initiated urate-lowering therapy and achieved the target within one year, 17.1% had a 30% or more improvement in eGFR compared with 10.4% of those who failed to reach the target, for a difference of 6.7% (95% CI 4-9.4, P<0.001).
The benefits of reaching the serum urate target on eGFR also were seen across the various stages of chronic kidney disease. In stage 2, the proportion of patients who had a 30% or greater improvement in eGFR was 7.1% for those who reached the target compared with 3.3% for those who did not -- a difference of 3.8% (95% CI 0.7-7, P=0.015).
The benefits were most notable in patients with stage 3 disease: 19.9% versus 10%, for a difference of 9.9% (95% CI 6.1-13.6, P<0.001), while in stage 4, the respective percentages were 30% versus 22.2%, for a nonsignificant difference of 7.8% (95% CI -1.1 to 16.8, P=0.080), Levy reported.
When the researchers calculated ratios for improvement in kidney function among patients who had a 30% improvement in eGFR plus those whose eGFR did not worsen, the odds ratios were 2.86 in stage 2 patients who reached the serum urate goal and 3.89 for stage 3 patients -- "encouraging information," he said.
However, for patients in stage 4, there was no improvement: "It was probably too late. Stage 3 seems to be the sweet spot."
The study suggested that patients with chronic kidney disease should undergo testing for uric acid, whether or not they have gout, Levy concluded. "In patients with significantly elevated serum uric acid and moderate kidney failure, the use of urate-lowering therapy may help stabilize kidney function."
Primary Source
American College of Rheumatology
Levy G, et al "Urate lowering therapy in moderate to severe chronic kidney disease" ACR 2016; Abstract 912.