CUA guideline on the evaluation and medical management of the kidney stone patient ‒ 2016 update

Despite technological advances in the surgical management of upper tract urinary stone disease that have significantly reduced patient morbidity and recovery time, new stone formation and recurrence remain significant health issues. Data from the U.S. National Health and Nutrition Examination Survey (NHANES) published in 2012 noted a kidney stone prevalence of 10.6% in men and 7.1% among women.1 Comparing these results to a similar survey conducted between 1976 and 1994, the overall prevalence of stone disease in the U.S. population has increased from 5.2 to 8.2%.2 An increase in stone formation, particularly among women, has also been observed such that the male:female ratio appears to be decreasing.3,4 Recent evidence also suggests there may be an increase in the incidence of certain stone compositions, such as uric acid, a type of stone clearly linked to both dietary and metabolic risk factors.5 Recurrence rates after an initial symptomatic stone event are reported to be from 30‒50% within 10 years of first presentation.6,7 Patients are, therefore, generally motivated to explore prevention strategies.1 Studies have shown, however, that patients are more willing to undergo metabolic evaluation compared to physicians’ willingness to further investigate them.8 Epidemiological data from the U.S. show that only 7% of patients with a high risk of recurrent stone disease undergo metabolic evaluation by any physician.9 The odds of undergoing metabolic evaluation were 2.9 and 3.9 times higher if patients were seen by a nephrologist or urologist, respectively. Bensaleh et al noted that 81% of patients interviewed would prefer to take a prophylactic medication than undergo another stone episode, and 92% of respondents preferred medication to undergoing surgery.8 In summary, the vast majority of stone patients would benefit from metabolic evaluation, but are not being investigated. The economic burden of recurrent stone disease is also significant. Estimates of direct costs to care for and treat patients with stones and the indirect costs related to lost work time exceed $5 billion USD.10,11 The observed increases in healthcare expenditures associated with nephrolithiasis are likely due to the increasing prevalence12 and procedure-related costs, despite a shift towards outpatient treatment, shorter length of hospital stay, and more minimally invasive procedures.11 Given the rising rates of obesity and diabetes and their association with stone formation, the cost of managing stone disease is expected to increase to 1.24 billion dollars yearly in the U.S. by 2030.13 Clearly, the need for stone prevention in those at risk will continue to have an important role. In 2010, the Canadian Urological Association (CUA) Guidelines Committee commissioned the development of a clinical practice guideline on the evaluation and medical management of patients with upper tract urolithiasis. The aims of the guideline were to help clinicians identify patients at heightened risk of stone recurrence, to outline the required investigations to assess these patients, and to provide up-to-date advice on dietary and medical interventions of proven benefit in the Canadian context. In accordance with the CUA’s policy of reviewing the content of guidelines every five years, this topic was felt to be ready for revision to reflect new advances in the preventative management of patients with renal stones. It should be noted that this guideline addresses the evaluation and medical prophylaxis of upper tract stones and not stones forming within the bladder.