David Goldfarb and colleagues ask: “More kidney stones or better detection?”
Clinical Journal of the American Society of Nephrology: CJASN. 2009 Mar;4(3):680-4. Epub 2009 Mar 4.
Asymptomatic nephrolithiasis detected by ultrasound.
Bansal AD, Hui J, Goldfarb DS.
Department of Medicine, New York University School of Medicine, New York, New York, USA.
Significance:
Recent data suggest that the prevalence of kidney stones is increasing. Increasing prevalance of overweight, diabetes and hypertension, condition all associated with stones, may in part be responsible. It is also possible that greater utilization of imaging techniques, both ultrasound and computed tomography (CT) is detecting a greater number of asymptomatic stones. People may answer in the affirmative when asked about a history of kidney stones, aware of their history only because asymptomatic stones were detected by an imaging study performed for an indication having nothing to do with stones or the urinary tract. In this paper we demonstrated a significant prevalence of asymptomatic stones in a population with no prior history of stones, suggesting that estimates of increasing prevalence should take into account greater utilization of imaging techniques.
Abstract:
BACKGROUND AND OBJECTIVES: Data from several countries suggest a recent world-wide increase in the prevalence of stone disease. However, these studies have not analyzed the effect that increases in utilization of imaging modalities have had on detection of asymptomatic stones.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A retrospective chart review of all patients who had an abdominal or retroperitoneal ultrasound in 2005 at a Department of Veterans' Affairs Medical Center was conducted. The charts of patients who had ultrasounds demonstrating kidney stones were further reviewed. Patients were classified into symptomatic and asymptomatic groups on the basis of their clinical history. Age and sex for all patients were recorded. For those patients with stones, additional data were recorded. Of all patients in the study, the percentage of those with asymptomatic stones was calculated. Taking into account uncertainty about symptomaticity in some patients, a sensitivity analysis for the presence or absence of gross and microhematuria was performed to determine a range for the percent of asymptomatic stones. Appropriate statistical tests were used to determine significance.
RESULTS: The prevalence of all kidney stones in the study group was 8.6 %. Using the sensitivity analysis, 29.8 to 45.7% of all stones were asymptomatic. Of stones found on abdominal ultrasounds, 71.4% were asymptomatic, whereas 36.8% of stones found on retroperitoneal ultrasound were asymptomatic.
CONCLUSIONS: Asymptomatic stones have a relatively high prevalence on ultrasound. Epidemiologic estimates of prevalence of nephrolithiasis need to account for increases in utilization of imaging modalities and the resulting detection bias.
PMID: 19261817