Does snake envenoming cause chronic kidney disease? A cohort study in rural Sri Lanka.

BACKGROUND: There is limited information on the risk of chronic kidney disease (CKD) following snakebite and its relationship with chronic interstitial nephritis in agricultural communities (CINAC). We aimed to investigate CKD in patients with a confirmed snakebite in rural Sri Lanka.

METHODS: Patients prospectively recruited to the Anuradhapura snakebite cohort with authenticated bites were followed up. Two groups of patients were followed up: 199 patients in group I with a snakebite (August 2013-October 2014), reviewed after 4 years, and 168 patients in group II with a snakebite (May 2017-August 2018), reviewed after one year, with serum creatinine (estimated glomerular filtration rate [eGFR]) and urinary albumin to creatinine ratio (ACR).

RESULTS: There were 12/199 (6%) in group I and 9/168 (5%) in group II with AKI following snakebite; 3/12 in group I and 2/9 in group II had haemodialysis. On review after 1 and 4 years, no patient had CKD and all had an eGFR ≥60 mL/min/1.73m2 . Of 234 patients with a creatinine measured on discharge, 17/140 in group I and 11/94 in group II had a low eGFR (<60mL/min/1.73m2 ). In group I, 14/17 had a normal eGFR after four years, including 11/12 who had AKI following snakebite, and the 3/17 with a low eGFR on review had CKD or co-morbidities for CKD. In group II, 10/11 had a normal eGFR after one year, including all nine patients with AKI following snakebite, and the one patient with a low eGFR on review had CKD. Fifty patients (25%) in group I and 43 (26%) in group II had a high urinary ACR on review, all but two in each group had microalbuminuria. Multivariate logistic regression showed in group I that only comorbidities for CKD were associated with high urinary ACR, and in group II comorbidities for CKD, snakebite associated AKI and snake type were associated with high urinary ACR. All nine patients from both groups with a low eGFR (CKD stages 3-5) had CKD prior to the snakebite or treatment for hypertension or diabetes.

CONCLUSION: There was no significant association between snakebite-associated AKI and CKD in patients followed up from a snakebite cohort post-bite. Microalbuminuria was common in these patients but likely associated with hypertension, diabetes mellitus and CINAC in this rural farming population.