Gout Diagnosis in Dialysis-Dependent Patients Linked to Higher Burden of Cardiovascular Comorbidities, Hospitalization, Mortality

Gout diagnosis, which was found in 13.5% of dialysis-dependent patients living in the United States, was associated with a higher burden of comorbid cardiovascular conditions and an elevated frequency of both hospitalization and mortality, according to a study published in Kidney360.¹ Findings underscore the importance of developing new and better treatments to improve outcomes in this patient population.

“Most studies of gout among patients with chronic renal disease have focused on pre-end-stage kidney disease (ESKD) patients,” Brad Marder, MD, Medical Director of Nephrology at Horizon Therapeutics, and a team of investigators, explained. “At present, very limited research exists regarding patients with ESKD with a gout diagnosis who require maintenance dialysis.”

Although dialysis is generally associated with a decrease in gout flares due to removal of uric acid, it is often unable to achieve target serum uric acid (sUA) levels, leading to the need for urate-lowering therapies (ULTs). In patients with ESKD, a gout diagnosis is linked to inflammation that may cause malnutrition, anemia, and other comorbidities.²

Data from the United States Renal Data System (USRDS) was utilized to perform a population-based retrospective cohort study of adult patients on dialysis who were covered by Medicare, which covers 93% of patients undergoing dialysis in the country. Primary outcomes included the presence of gout among patients on maintenance dialysis during 2017, all-cause mortality, and composite outcome including death and hospitalization for myocardial infarction (MI), congestive heart failure (CHF), and stroke.

Potential factors and odds of gout diagnosis were determined using multivariate logistic regression models. Further, descriptive and regression analyses evaluated the impact of antigout medications on anemia management for patients with and without a gout diagnosis. All-cause mortality and cardiovascular-related hospitalizations during a 1-year follow-up period were compared between patients with and without gout via multivariate Cox regression models.

Of the 231.841 patients with ESKD enrolled in Medicare Part A and B undergoing dialysis in 2017, 13.5% (n = 31,300) had at least 1 gout diagnostic code. In patients with gout, approximately 75% had ≥1 gout diagnosis within the last 2 years, which signified that most patients had a preexisting gout diagnosis.

These odds independently increased in patients who were older in age, male, obese, Asian, had a hypertension diagnosis, and those with cardiovascular disease. Additionally, patients were more likely to live in assisted living, nursing homes, or other institutions.

Gout was linked to a higher prevalence of anemia, which was indicated by increased erythropoietin-stimulating agent (ESA) requirements (odds ratio [OR] = 1.18, 95% confidence interval [95% CI], 1.14 – 1.22) and likelihood of blood transfusions (OR =1.34, 95% CI, 1.30 – 1.38). ESA doses were roughly 10% higher in patients with gout (P <0.0001).

At 1-year follow-up, 17.2% (n = 39,970) patients had died and 0.13% (n = 301) received a kidney transplant. Multivariable Cox proportional hazards regression analyses showed that mortality among patients with gout was 3% higher when compared with patients without a gout diagnosis during the follow-up period (hazard ratio [HR], 1.03; 95% CI, 1.00 – 1.06). A composite of death of cardiovascular disease (CVD) hospitalizationwas 6% higher in patients with gout after adjusting for comorbidities (HR, 1.06; 95% CI, 1.04 – 1.10).

Misclassification of study measures may have occurred due to USRDS’s reliance on Medicare billing claims. Additionally, as the patients were required to be on continuous dialysis for the entirety of 2017, the study may have introduced survivor bias because patients with a higher number of comorbidities may have died before completing the full year. However, the large sample size and reliability of the USRDS database strengthened the study. Further, as Medicare covers the vast majority of patients, results are generalizable among this population.

“Patients with ESKD on dialysis represent a vulnerable group of patients with a high risk for mortality and morbidity within the US population,” investigators concluded. “Notwithstanding the complexity of medical care required for these patients, these results suggest a significant opportunity exists to improve both quality of life and potentially cardiovascular risk in dialysis-dependent patients with coexisting gout.”

References

1. ^{Zhang Y, Kshirsagar O, Marder BA, Cohen AR, LaMoreaux B, Bleyer AJ. Gout among Patients with Dialysis: Prevalence, Associated Factors, Treatment Patterns, and Outcomes-Population-Based Retrospective Cohort Study. Kidney360. 2023;4(2):177-187. doi:10.34067/KID.0004132022}
2. ^{McAdams-DeMarco MA, Maynard JW, Coresh J, Baer AN. Anemia and the onset of gout in a population-based cohort of adults: Atherosclerosis Risk in Communities study. Arthritis Res Ther. 2012;14(4):R193. doi:10.1186/ar4026}