Urinary calculi and an increased risk of stroke: a population-based follow-up study.

UNLABELLED: Study Type--Prognosis (cohort) Level of Evidence 2b. What's known on the subject? and What does the study add? Although early studies failed to detect an association between urinary calculi (UC) and subsequent cardiovascular risk, there is growing evidence among more recent research supporting this association with some studies more specifically suggesting that stroke is a major concern for UC sufferers. After adjusting for potential confounding factors, UC patients were more likely to have experienced a stroke then those without UC during the five-year follow-up period (hazard ratio = 1.43, 95% Cl = 1.35-1.50, P < 0.001).

OBJECTIVE: • To examine in a population-based study the relationship between a history of nephrolithiasis and/or ureterolithiasis and the subsequent risk of stroke, as previous studies have shown that stone disease is associated with several cardiovascular risk factors. However, none of the studies that have investigated the relationship between urinary calculi (UC) and stroke were able to detect an association at a significant level.

PATIENTS AND METHODS: • We used data sourced from the Taiwan Longitudinal Health Insurance Database 2000. • In all, 25,181 adult patients newly diagnosed with UC were recruited as a study cohort, along with 125,905 matched enrolees with no history of stone disease as a comparison cohort. • All the subjects were tracked for a 5-year period beginning from their index ambulatory care visits, and those who subsequently had a stroke identified. • Cox proportional hazards regressions were used to compare the risk of stroke between the study and comparison cohorts.

RESULTS: • During the 5-year follow-up period, the incidence rate of stroke was 1.78 (95% confidence interval [CI] 1.71-1.86) per 100 person-years in patients with UC and 1.25 (95% CI 1.22-1.27) per 100 person-years in patients without UC. • After adjusting for hypertension, diabetes, hyperlipidaemia, cardiovascular disease, urbanization level, gout, and obesity, patients with UC were more likely to have had a stroke than those without UC during the 5-year follow-up period (hazard ratio 1.43, 95% CI 1.35-1.50, P < 0.001).

CONCLUSION: • Our results suggest that there is an increased risk of stroke during the first 5 years after a diagnosis of UC.