Trends of stone composition in Hong Kong over a decade

Abstract

Introduction and objectives: Diet high in animal fats and obesity in recent years have been shown to increase the proportion of female stone formers as well as uric acid stones in Western countries. This study aims to identify the changing trends of stone composition in Hong Kong over the past decade. Identifying such trends could help in formulating strategies for tackling the problem of renal stones in Hong Kong. Materials and methods: Patients with upper urinary tract stones and subsequent stone analysis results were identified through the clinical management system from 2004 to 2005 (referred to as 2000s) and from 2015 to 2016 (referred to 2010s). Patient records were retrieved and demographics, nature of stones on analysis, and location of stones were identified. Categorical data were analyzed with Chi-square test whereas continuous variables were analyzed with t-test. Results: 70 patients were identified in 2000s, whereas 66 patients were identified in 2010s. Mean age of patients in 2000s were 56.3 years old compared with 51.4 years old in 2010s (P = 0.07). 70% were males in 2000s vs 59.1% in 2010s; a rise in female stone formers was noted but it was not statistically significant (P = 0.211). In general, there were more patients with carbonate (P = 0.001) & oxalate stones (P = 0.001) in 2010s and less calcium phosphate (P = 0.001) and struvite stones (P = 0.045). These findings were reflected in males but less so in females on subgroup analysis. Interestingly, there were no increase in uric acid stones in our study. Conclusion: There was a change from calcium phosphate and struvite stones to carbonate and calcium oxalate stones in the past decade in Hong Kong. There were no increase in uric acid stones as seen in other studies performed in Western countries.