AUA: Lithotripsy-Diabetes Link Remains Unresolved

By Charles Bankhead
ORLANDO, 29 may 2008-- Recent studies have suggested that extracorporeal shockwave lithotripsy increases the risk of diabetes, but new research presented here fails to clarify the issue.
One study reported at the American Urological Association meeting found no connection between lithotripsy and diabetes, another revealed a positive association, and a third showed that obesity and older age -- not the mode of stone removal -- were factors.
To examine the link, Antoine Makhlouf, M.D., of the University of Minnesota in Minneapolis, and colleagues used a mail survey to collect information on 1,942 patients treated between 1999 and 2002 with the same lithotripsy machine. For comparison the investigators used data from participants in the National Health and Nutrition Examination Survey (NHANES), matched for age, sex, and body mass index.
At the time of lithotripsy, 8.67% of the patients had a diabetes diagnosis, which increased to 13.9% by the 2007 follow-up survey. Over the same period the prevalence of diabetes in the NHANES control group increased from 8.34% to 14.1%.
From the similar rate of increase (5.2% in the lithotripsy group compared with 5.6% in the NHANES group, P=0.07), Dr. Makhlouf and colleagues concluded that lithotripsy does not increase the risk of diabetes.
In the second study, Canadian investigators examined the association between lithotripsy and diabetes in 152 patients who underwent the procedure at Vancouver General Hospital between 1985 and 1987. Diabetes status approximately 20 years later was assessed by means of a telephone survey. Mean age of patients at the time of the survey was 67.4 years.
The lithotripsy patients had more than twice the rate of diabetes compared with the general population, reported Ben Chew, M.D., of the University of British Columbia in Vancouver.
The overall diabetes prevalence in the lithotripsy patients was 26.3%, including 29.4% in men and 20% in women. That compared with a background prevalence of 10.1% in men and 9.1% in women in the general population of British Columbia.
Noting that the study lacked a proper control group, the researchers said. "It would be premature to conclude that this increased prevalence is due to [lithotripsy] alone. It may be attributable to the fact that diabetic patients are prone to developing stone disease and that diabetes does not manifest until later in life."
Despite the uncertainty surrounding the data, the study "supports that an association exists," the authors concluded.
Matthew C. Kincade, M.D., of the University of Tennessee at Memphis, and colleagues compared the prevalence of diabetes and hypertension in patients who had kidney stones treated with lithotripsy or ureteroscopy from 2002 to 2007. The study involved 712 patients who underwent lithotripsy and 146 who had stones removed ureteroscopically.
At baseline, 634 lithotripsy patients (89%) and 113 ureteroscopy patients (93%) were free of diabetes. Additionally, 408 (57%) lithotripsy patients and 69 (56%) ureteroscopy patients did not have pre-existing hypertension.
During follow-up, 9.1% of the group treated with lithotripsy and 7.4% of the ureteroscopy group developed new-onset diabetes.
New diagnoses of hypertension were documented in 21.1% of the lithotripsy group and 14.5% of patients who underwent ureteroscopy.
In a multivariate analysis, the type of treatment for stone disease did not influence the risk of diabetes or hypertension. Age 60 and older and BMI ≥30 were the only significant predictors of diabetes risk, and only BMI ≥30 predicted an increased risk of hypertension.
"ESWL is a safe option for the treatment of urinary stone disease when compared to ureteroscopy," Dr. Kincade and colleagues concluded. "Patients with increased BMI . . . are at increased risk for both de novo diabetes and de novo hypertension after treatment of stones with either ESWL or ureteroscopy. Patients 60 years of age or greater are at an increased risk of developing de novo diabetes after treatment of stone disease."
Dr. Makhlouf disclosed that he is a consultant/adviser for Timm Medical Technologies and American Medical Systems. Dr. Chew disclosed relationships with multiple commercial interests. Dr. Kincade had no disclosures.
Primary source: Journal of UrologySource reference:Makhlouf AE, et al "Extracorporeal shockwave lithotripsy does not increase the risk of diabetes" J Urol 2008; 179(suppl): 462. Abstract 1350.