Gout in Patients With Advanced Chronic Kidney Disease

Individuals with compromised kidney function are at an increased risk of gout, a common but potentially serious inflammatory arthritis. As many as 24% of patients with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² experience gout. Meanwhile, patients with both gout and hyperuricemia (uncontrolled gout with serum urate >6 mg/dL) are at a higher risk of chronic kidney disease (CKD). Thus, recognizing and managing concurrent gout and CKD is important for improving outcomes. However, management of gout and hyperuricemia with CKD can be difficult due to constraints on the use of oral urate-lowering therapy (ULT) and gout flare treatment and prophylaxis.

Therefore, Leonard Stern, MD, and other researchers conducted a chart review of patients with CKD at nephrology clinics with the goal of better understanding the prevalence, associated comorbidities, and medical management of gout in a large cohort of patients with moderate to advanced CKD. Their study results appeared in Gout, Urate, and Crystal Deposition Disease.

A group of 443 nephrologists responded to a request for anonymized chart data from patients with CKD stages 3 to 5 (eGFR <60 mL/min/1.73 m²). Gout was not mentioned as the subject of the study. Ultimately, 746 patient charts from 111 nephrologists comprised the study group.

Physicians selected the advanced CKD patients they had seen most recently, within 3 months before data collection. Mean eGFR among the 746 patients was 32.2±15.5 mL/min/1.73 m², 54% were male, and mean age was 56.2±18.3 years. They had a CKD history of 4.0±4.8 years, and the mean body mass index was 31.4±10.9 kg/m². There were 123 patients (16%) with end-stage renal disease and 61 (8%) who were transplant recipients; 90% of those were renal transplants.

For purposes of the study, gout was defined as being listed as a comorbidity, ULT use, and/or reported gout symptoms (tophi, >1 flare). Uncontrolled gout was defined as hyperuricemia (serum urate >6 mg/dL) with tophi, ≥2 gout flares/year, or ≥1 swollen/tender joint. Of the 746 patients with CKD who were included in the study, 173 (23%) met the criteria for gout. Most of these patients had CKD stage 3b or 4 (both 28%). There were 110 patients (64%) in the gout group who had gout listed as a comorbidity and 109 (64%) who were using a ULT. More than one-third of patients with gout did not have a gout diagnosis in their medical records. There were 135 patients with known flare occurrence; of those, 40 (30%) had at least one acute gout flare within the previous year. Of 131 patients in whom gout-related pain was known, 67 (51%) reported chronic pain.

Although baseline characteristics were similar between patients with and without gout, those with gout were significantly more likely to have diagnoses of CKD-mineral bone disorder (40% vs 26%; P<.001), ischemic heart disease (23% vs 13%; P=.004), congestive heart failure (21% vs 14%; P<.001), peripheral vascular disease (15% vs 9%; P=.03), and chronic back pain (13% vs 6%; P=.008). Patients with gout also had higher HbA1c levels (7.5±1.40 vs 7.1±1.38 mmol/mol; P=.02), more shortness of breath (21% vs 14%; P=.02), urination changes (15% vs 7%; P=.001), and joint symptoms (16% vs 7%; P<.001).

The prevalence of comorbidities was similar between patients with controlled and uncontrolled gout, but pulmonary hypertension (14% vs 4%; P=.04) occurred significantly more often, and diabetes (27% vs 50%; P=.03) was present significantly less often in patients with uncontrolled gout. Patients with uncontrolled gout had ≥2 gout flares in the prior year (48% vs 26%; P=.0495) and more often had degenerative joint disease (32% vs 15%; P=.06) versus those with controlled gout.

Limitations cited by the study’s authors were primarily a result of its retrospective and cross-sectional nature. Among their concerns, the researchers noted that differences observed between patients with and without gout cannot be used to determine causality. Recall bias was possible. and data accuracy was subject to question. It is possible that some patients without gout were incorrectly labeled as having gout, and others might have been improperly included in the “controlled gout” population. Finally, the number of patients with uncontrolled gout was small.

“In conclusion, these data suggest that gout negatively impacts cardiovascular and bone health in patients with advanced CKD, with uncontrolled gout adding additional health burden,” the authors wrote. “Importantly, over one-third of patients with gout signs and symptoms and/or taking a ULT did not have a formal gout diagnosis in the medical record, and over one-third of patients who had a gout diagnosis were not receiving a ULT. In addition to avoiding the painful and debilitating joint sequelae of untreated gout, our data suggest that improved management of gout in CKD patients could also represent an important opportunity to improve overall patient health and well-being.”

Source: Gout, Urate, and Crystal Deposition Disease