People with gout are around 30% more likely to develop advanced chronic kidney disease than their peers, a UK study suggests.
In the study, around 70,000 patients with gout and 600,000 patients without gout were matched by age, sex and GP clinic.
After adjusting for possible confounders (like medications, lifestyle and co-morbidiites) the researcher found that patients with gout were 29% more likely to develop advanced chronic kidney disease than the non-gout group over four years.
The patients with gout were also more than twice as likely to develop end-stage kidney disease than their peers.
The observational research was published in BMJ Open in August. The study was funded by AstraZeneca.
“This is an important and well-done study which adds to previous work which has suggested an independent adverse effect of gout on renal function,” said Associate Professor Neil McGill, a rheumatologist based in Sydney.
The results fit in with experimental studies showing that elevated uric acid levels inflict renal injury via intraglomerular hypertension and the development of tubulointerstitial fibrosis, the authors said.
But it was possible that the apparent increased risk of kidney disease from gout was due to unmeasured confounding factors, they said.
“Although the increased risk persisted after correction for these other risk factors, the authors acknowledged that there remained a possibility of residual confounding,” said Associate Professor McGill.
“The critical studies that will clarify the effect of gout on renal function are the intervention studies of urate lowering drug therapy (allopurinol and febuxostat) are currently underway.”
Professor Austin Stack, a nephrologist from the University of Limerick in Ireland and the lead author of the study, said: “The clinical community has always believed that high levels of uric acid might be bad for kidneys and that patients who suffered from gout were at greater risk of kidney failure than those without gout.
“Our study is the largest and most detailed study published to-date that has examined in detail the link between gout and risk of advanced CKD including kidney failure in over 620, 000 patients.
“We have confirmed that there is a very strong link between gout and the development of advanced CKD, which is not explained by hypertension, diabetes or several other factors.”
The identification of gout as a potential risk factor opened up several new opportunities for the prevention of kidney disease and its consequences, he said.
“First, patients with a diagnosis of gout should be viewed as a high-risk group for kidney disease and should be screened for kidney disease with blood test and urine sample.
“Second, every effort should be made to get good control of gout as per international guidelines, although it is not yet proven whether optimal control (achieving target uric acid levels < 360 µmol/L) can reduce the risk of kidney failure.
“Third, many patients with gout have other conditions such as diabetes or hypertension, and these should be treated effectively in order to reduce overall risk.
“Finally, we encourage the conduct of new clinical trials need to test whether better control of gout leads to less kidney failure.”
BMJ Open 2019, 31 August