Better outcomes for patients with kidney stones: study

Dialysis

By Siobhan Calafiore

3 Jul 2024

Patients with kidney failure as a result of kidney stones appear to have a survival advantage over patients with kidney failure due to other causes when undergoing dialysis, although this advantage doesn’t extend to transplantation, Australian data suggest.

The study involved 78,705 adult patients with kidney failure who commenced kidney replacement therapy (dialysis or transplantation) between 1981 and 2020 from the Australia and New Zealand Dialysis and Transplant (ANZDATA) registry.

This equated to a total follow-up time of 285,250.4 patient-years.

Of these patients, 834 (1.1%) began kidney replacement therapy (KRT) due to renal calculi.

The crude incidence for the cohort was 1.17 cases per million population per year (men 1.27 and women 1.07 per million population), with the annual incidence remaining stable for the 40-year study period (annual percentage change -0.3%).

Although incidence appeared to have declined annually over the last 10-15 years, noted the researchers in Nephrology Dialysis Transplantation [link here].

“This is noteworthy when viewed in context of an increasing global prevalence of kidney stones in the general population,” the researchers wrote.

“We are unable to examine possible causes or contributing factors for this decline, but it may reflect better management incorporating life-style advice or medications, patient awareness and follow-up of patients with kidney stones, translating into a lower risk of progression to kidney failure.”

Patients starting KRT due to calculi as opposed to other causes were less likely to be male (53% vs 60%), older (62 vs 59) and less likely to have diabetes (26% vs 45%) and peripheral vascular disease (17% vs 24%), the researchers noted.

During follow-up, more than half of patients died (55%), one quarter received a transplant and one in five reached the end of the study period.

Findings showed that patients with kidney stones on dialysis had higher survival versus kidney failure patients without kidney stones (hazard ratio [HR], 0.89) in the adjusted analysis. Estimates were similar in the matched cohort (HR 0.87).

The researchers said their results should be reassuring, although suggested the increased risk of mortality in the control group could be possibly explained by almost half of patients having kidney failure due to diabetes or renovascular causes.

As for transplant patients, wait times were significantly longer for patients with kidney stones compared to those without (2.5 years vs 1.7 years, respectively).

“The risk and concern of recurrence may explain why we found a significant delay in time to transplantation between the two groups, with patients with kidney failure due to kidney stones waiting an average of almost a year more to undergo kidney transplantation,” the researchers said.

However, there was no differences in risk of mortality (HR 1.02) or graft failure (HR 1.07) between kidney stones versus non-kidney stones in the kidney transplant group, with death and graft failure occurring in 35% and 24% of participants overall.

Again, there were similar estimates in the matched group (HR 0.94 and 1.04).

The researchers noted they could not examine the risk of kidney stone recurrence post transplant, and were also unable to confirm stone type or the severity of kidney stone disease, which would have added more information and value to the study.

“Our results can be used to inform and reassure care providers in the management of patients with kidney stones, particularly those approaching kidney failure and who are being considered for dialysis or transplantation,” they concluded.

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