October 04, 2017
The Journal of Urology
TAKE-HOME MESSAGE
- Using data from the Health Professionals Follow-Up Study and the Nurses’ Health Study, this study characterized the association of modifiable risk factors with the incidence of stone disease. Investigators found that maintaining a normal BMI, consuming an adequate amount of fluid, eating a balanced diet rich in fruits and vegetables, and avoiding sugar-sweetened beverages were protective with respect to incident stone events in multiple large prospective observational cohort studies.
- These data underscore the importance of lifestyle and dietary factors in driving stone risk, and should be emphasized at every clinic visit to minimize the burden of stone disease in high-risk populations.– Matthew Resnick, MD, MPH, MMHC
Primary Care
Reducing kidney stone risk in half with lifestyle choices
This study evaluated 192,126 people from the Health Professional’s Follow-Up Study (HPFS) and the Nurses’ Health Study (NHS) and documented the diagnosis of a first-time kidney stone, of which the majority (86%) was composed of calcium oxalate. The participants were then placed in low- and high-risk categories for five lifestyle factors that have been associated with the risk of kidney stones. The results suggested that if an individual went from high to low risk in these five categories, the incidence of kidney stones would be reduced by half.
The five factors were found to reduce the risk of kidney stones by 50%.
The lifestyle factors that had the greatest protective benefit were adequate water intake in the HPFS cohort (more men), with a number needed to prevent (NNTP) of 67, and a low BMI in the NHS cohort (more women), with a NNTP of 138. When all five factors were added together, the NNTP for the HPFS cohort was 19 and the average NNTP for the NHS cohort was 30.
For those who have recurring calcium oxalate stones despite lifestyle changes, adding a thiazide diuretic (hydrochlorothiazide or chlorthalidone) to reduce calcium buildup in the kidneys may be all the doctor needs to order.
Abstract
PURPOSE
Several dietary and lifestyle factors are associated with a higher risk of kidney stones. We estimated the population attributable fraction and the number needed to prevent for modifiable risk factors, including body mass index, fluid intake, DASH (Dietary Approaches to Stop Hypertension) style diet, dietary calcium intake and sugar sweetened beverage intake.
MATERIALS AND METHODS
We used data on the HPFS (Health Professionals Follow-Up Study) cohort and the NHS (Nurses’ Health Study) I and II cohorts. Information was obtained from validated questionnaires. Poisson regression models adjusted for potential confounders were used to estimate the association of each risk factor with the development of incident kidney stones and calculate the population attributable fraction and the number needed to prevent.
RESULTS
The study included 192,126 participants who contributed a total of 3,259,313 person-years of followup, during which an incident kidney stone developed in 6,449 participants. All modifiable risk factors were independently associated with incident stones in each cohort. The population attributable fraction ranged from 4.4% for a higher intake of sugar sweetened beverages to 26.0% for a lower fluid intake. The population attributable fraction for all 5 risk factors combined was 57.0% in HPFS, 55.2% in NHS I and 55.1% in NHS II. The number needed to prevent during 10 years ranged from 67 for lower fluid intake to 556 for lower dietary calcium intake.
CONCLUSIONS
Five modifiable risk factors accounted for more than 50% of incident kidney stones in 3 large prospective cohorts. Assuming a causal relation, our estimates suggest that preventive measures aimed at reducing those factors could substantially decrease the burden of kidney stones in the general population.
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