Association of hyperuricemia and serum uric acid lowering therapy with mortality in hemodialysis patients

Gout among Patients with Dialysis: Prevalence, Associated Factors, Treatment Patterns, and Outcomes-Population-Based Retrospective Cohort Study

Key Points

Population-based retrospective cohort study to evaluate clinical correlates of gout and its impact on patients undergoing chronic dialysis. 13.5% of US dialysis-dependent patients had gout and were older and male, with a higher prevalence of hypertension and cardiovascular disease. Gout diagnosis was associated with a higher incidence of cardiovascular conditions, levels of anemia, hospitalization, and mortality.

Background

An association between gout and nondialysis chronic renal disease has long been recognized, yet limited research exists regarding prevalence, treatment, anemia management, and outcomes in patients with ESKD undergoing dialysis.

Methods

Using data from United States Renal Data System, we conducted a population-based retrospective cohort study in adult patients covered by Medicare and on dialysis in 2017. Multivariate logistic regression models were used to estimate potential factors and odds of gout diagnosis. Antigout medications and impact on anemia management were assessed and compared between gout and nongout dialysis patients using descriptive and regression analyses. Associations for all-cause mortality and cardiovascular-related hospitalizations during 1 year of study follow-up were compared between gout and nongout patients using multivariate Cox regression models.

Results

Of 231,841 ESKD Medicare patients in 2017 undergoing continuous dialysis, 31,300 (13.5%) had one or more gout diagnostic code(s). Increased odds of having a gout diagnosis were independently associated with older age, male sex, Asian race, obesity, hypertension, and cardiovascular disease. Gout diagnosis was associated with higher prevalence for anemia as indicated by increased erythropoietin-stimulating agent requirements (odds ratio=1.18 for high versus low erythropoietin-stimulating agent dose, 95% confidence interval [95% CI], 1.14 to 1.22) and likelihood of blood transfusions (odds ratio=1.34, 95% CI, 1.30 to 1.38). During the 1-year study follow-up, mortality among gout versus nongout patients was higher by 3% (95% CI, 0 to 6) and a composite association of mortality and cardiovascular disease hospitalization was higher by 6% (95% CI, 3 to 9) after adjusting for comorbid conditions.

Conclusions

A gout diagnosis was found in 13.5% of US dialysis-dependent patients and was associated with a higher burden of comorbid cardiovascular conditions as well as an elevated incidence of hospitalization and mortality. These observations improve our current understanding of gout among the dialysis population and highlight the importance of new and better treatments to improve outcomes.

Urate-lowering therapy for patients with gout on hemodialysis

OBJECTIVE

Gout is the most common form of inflammatory arthritis and is caused by deposition of monosodium urate crystals resulting from a high burden of uric acid (UA). High UA burden also has been associated with increased morbidity and mortality in the general population and progression to chronic kidney disease. In persons with gout and end-stage renal disease (ESRD), prior studies suggest that UA levels decrease after initiation of hemodialysis (HD). We evaluated UA level and the use of urate-lowering therapies (ULTs) in patients with gout and ESRD on HD.

METHODS

We performed a retrospective review of patients with gout and ESRD seen at a large urban public hospital (The MetroHealth System). We extracted data from the medical record (Epic) for patients diagnosed with gout and ESRD on HD. The main outcomes were the UA level and the use of ULTs before and after HD initiation.

RESULTS

We identified 131 patients with gout on HD. Of these, 21 patients had crystal proven gout diagnosis, 10 of whom had data on UA level pre-HD and post-HD and were included in the analysis. For the total sample (N = 21), the mean age was 65 years, 7 were female and 20 were African American. Mean pre-HD and post-HD UA levels were 8.4 and 3.98 mg/dL respectively. Twenty-one patients were receiving ULT pre-HD, 11 discontinued post-HD.

CONCLUSION

Among patients with gout and ESRD, we observed a decrease in UA level associated with initiation of HD. For this group, discontinuation of ULTs may be appropriate.

Correlation analysis of low-level serum uric acid and cardiovascular events in patients on peritoneal dialysis

Background

The impact of serum uric acid (SUA) on development of cardiovascular disease (CVD) in patients undergoing peritoneal dialysis (PD) remains controversial, especially the impact of hypouricemia (HUA) on CVD. The aim of our study was to investigate the influence of low-level SUA on cardiovascular (CV) events in PD patients.

Methods

A retrospective cohort study was conducted.728 PD patients from February 1, 2010 to May 31, 2019 were enrolled. All demographic and laboratory data were collected at baseline and 6 months after PD treatment. The study cohort was divided into four groups according to SUA level (μmol/L) after 6 months of PD: Group1 (< 360), Group2 (360–420), Group3 (420–480), Group4 (≥ 480). The clinical characteristics of each group were analyzed. With Group2 as reference, logistic regression analysis was performed to investigate the correlation between SUA levels and risk of CV events in patients undergoing PD. Use Kaplan–Meier method to generate CV events risk graph.

Results

728 patients were enrolled in this study, including 403 (55.4%) males and 325 (44.6%) females, with an average age of 48.66 ± 13.98 years; of which 158 (21.7%) patients developed CV events. Multivariate COX regression showed that after adjusting for multiple clinical factors, Group1 (HR = 1.92, 95% CI 1.17–3.15, P = 0.01), Group3 (HR = 1.89, 95% CI 1.13–3.15, P = 0.015), and Group4 (HR = 2.38, 95% CI 1.35–4.19, P = 0.003) are all independent risk factors for developing CV events. The Kaplan–Meier risk curve of CV events showed that the risk of CV events in the Group1, Group3 and Group4 were significantly higher (Log-Rank = 12.67; P = 0.005). Restricted cubic spline (RCS) showed that SUA level is non-linearly associated with the risk of CV events, showing an U-shaped curve (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi_{4}^{2}$$\end{document}χ42=13.3 P = 0.01).

Conclusions

Our study suggested that patients with SUA level less than 360 μmol/L also exhibited the higher risk for developing CV events, an U-shaped association between SUA level and risk of CV events in patients undergoing PD. Both SUA levels below 360 μmol/L and above 420 μmol/L were found to be significant risk factors for developing CV events in patients undergoing long-term PD.