A pilot study of behavioral, environmental, and occupational risk factors for chronic kidney disease of unknown etiology in Sri Lanka

Abstract

Chronic kidney disease of unknown etiology (CKDu) was first recognized in Sri Lanka in the early 1990s, and since then it has reached epidemic levels in the North Central Province of the country. The prevalence of CKDu is reportedly highest among communities that engage in chena and paddy farming, which is most often practiced in the dry zone including the North Central and East Central Provinces of Sri Lanka. Previous studies have suggested varied hypotheses for the etiology of CKDu; however, there is not yet a consensus on the primary risk factors, possibly due to disparate study designs, sample populations, and methodologies. The goal of this pilot case-control study was to evaluate the relationships between key demographic, cultural, and occupational variables as risk factors for CKDu, with a primary interest in pesticide exposure both occupationally and through its potential use as an ingredient in brewed kasippu alcohol. A total of 56 CKDu cases and 54 control individuals were surveyed using a proctored, self-reported questionnaire. Occupational pesticide exposure and alcohol consumption were not found to be significant risk factors for CKDu. However, a statistically significant association with CKDu was observed with chewing betel (OR: 6.11, 95% CI: 1.93, 19.35), age (OR: 1.07, 95% CI: 1.02, 1.13), owning a pet dog (OR: 3.74, 95% CI: 1.38, 10.11), water treatment (OR: 3.68, 95% CI: 1.09, 12.43) and pests in the house (OR: 5.81, 95% CI: 1.56, 21.60). The findings of this study suggest future research should focus on practices associated with chewing betel, potential animal interactions including pests in the home and pets, and risk factors associated with water. AUTHOR SUMMARYSince a new variant of chronic kidney disease was acknowledged in the early 1990s among those in the agricultural community of Sri Lanka, especially rice farmers, the research community has searched for causes of what has become known as chronic kidney disease of unknown etiology or CKDu. Previous studies have focused on heavy metals in the environment as they are known to be toxic to the kidneys however, a proverbial "smoking gun" has yet to be identified. Understanding that the causes is potential multifactorial we implemented a pilot case-control study using a One Health methodology administering a comprehensive interview to assess environmental, animal, and, human exposures that may be contributing to the diagnosis of CKDu. We found statistically significant odds ratio among those that reported having a pet dog, chewing betel (a traditional preparation or various ingredients wrapped in a betel leaf inserted between the teeth and cheek), pests in the home, treating drinking water, and older age. These results serve to guide further hypothesis generation regarding mechanisms behind associated exposures from infectious diseases such as hantavirus and leptospirosis to food preparation through boiling drinking water in aluminum vessels and oral pesticide exposure linked to betel preparation.