Orlando–Gout, caused by primarily by elevated serum uric acid in the blood, is the most common form of inflammatory arthritis. Recommendations in guidelines from the American College of Rheumatology call for lowering serum uric acid levels to <6 mg/dL for all patients with gout. Elevated serum uric acid is also associated with chronic kidney disease and results of previous studies suggest that urate-lowering therapy, predominantly xanthine oxidase inhibitors (XOIs), can slow progression of renal disease.
Jean J. Lim, MD, and colleagues recently conducted a study to examine the prevalence of CKD among adult gout patients in the United States, both controlled and uncontrolled, stratified by XOI treatment status. Controlled gout was defined as serum uric acid level <6 mg/dL and uncontrolled as serum uric acid level ≥6 mg/dL. Study results were reported during a poster session at the NKF 2017 Spring Clinical Meetings in a poster titled Prevalence of CKD and Uncontrolled Gout among US Adults: Results from NHANES 2007-2012.
The researchers utilized data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012. NHANES is conducted by the National Center for Health Statistics and is used to estimate the disease prevalence of the non-institutionalized US population. The study sample included respondents with valid data of gout status, sex, race/ethnicity, serum uric acid and serum creatinine levels; individuals <20 years of age were excluded.
Study measures included CKD defined following the 2002 National Kidney Foundation Kidney Disease Outcomes Quality Initiative, using estimated glomerular filtration rate (eGFR) as a marker of renal function and albumin-creatinine ratio (ACR) as a marker of renal damage. Other study measures were gout, uncontrolled gout, gout medication, hypertension, obesity, diabetes, cardiovascular disease, demographic variables, and health insurance status.
Of the 15,868 respondents in NHANES 2007-2012, 715 individuals had been told by a physician that they had gout. Those respondents represented an estimated total of 7.7 million US individuals with gout (US prevalence of 3.7%). Among the estimated gout population, 74% (n=5.7 million) had normal to stage 2 CKD, 15% (n=1.1 million) had stage 3a CKD, and 11% (n=0.8 million) had stage 3b to 5 CKD. Of those with gout, 22% with normal to stage 2 CKD, 42% with stage 3a CKD, and 44% with stage 3b to 5 CKD were currently being treated with an XOI; most of those taking an XOI were taking allopurinol.
Comorbidities in the overall estimated gout population were obesity (54%), diabetes (24%), hypertension (69%), and cardiovascular disease (22%). Those with more severe CKD had higher proportions of hypertension and cardiovascular disease.
Regardless of CKD stage, the majority of gout was uncontrolled: 63% in normal to stage 2 CKD, 62% in stage 3a CKD, and 72% in stage 3b to 5 CKD. In those with normal to stage 2 CKD, 44% of those taking an XOI had uncontrolled gout and 68% of those not taking an XOI had uncontrolled gout. In the population with stage 3a CKD, 36% taking an XOI had uncontrolled gout and 80% of those not taking an XOI had uncontrolled gout. Among those with stage 3b to 5 CKD, 57% of patients taking an XOI had uncontrolled gout and 83% of those not taking an XOI had uncontrolled gout. Of the overall population taking an XOI, 34% were uncontrolled and had normal to stage 3a CKD.
In conclusion, the researchers said, “The majority of non-institutionalized US adults who self-report that they have been diagnosed with gout have uncontrolled gout regardless of CKD stage, with the highest proportion of uncontrolled gout among those patients who have stage 3b to 5 CKD. Among those estimated gout patients who are taking an XOI, 34% are uncontrolled and have normal to stage 3a CKD, and therefore, may benefit from alternative treatment options indicated for their CKD stage.”
Source: Lim JJ, Fu AC, Reasner D, Taylor DCA. Prevalence of CKD and Uncontrolled Gout among US Adults: Results from NHANES 2007-2012. Poster presented at the National Kidney Foundation 2017 Spring Clinical Meetings, April 19-22, 2017, Orlando, Florida.