Chronic Kidney Disease of undetermined cause (CKDu), an emerging disease in developing nations

Abstract

OPS 25: Drinking water contamination and adult health, Room 411, Floor 4, August 26, 2019, 10:30 AM - 12:00 PM Background: There is increasing recognition of epidemics of primarily tubular-interstitial chronic kidney disease (CKD) clustering amongst working-age populations in agricultural communities in low-and-middle-income countries. These conditions have been termed CKD of undetermined cause (CKDu) due to unidentified underlying aetiology. Hypothesised causes include heat stress and heavy metal exposure through potable water. Our aim was to investigate CKDu presence in Malawi, and identify potential risk factors including nephrotoxic heavy metals in potable drinking water. Methods: Blood and urine samples (n=770) taken from an urban and rural study site (January-August 2018) were used to estimate kidney function across the sample population. We applied linear and logistic regression models with postulated risk factors including age, sex, education, residence, vegetarianism, and body mass index to estimate risk of low glomerular filtration rate (eGFR) (<90 ml/min/1.73m2). We collected potable water samples which were tested for trace metals by Nottingham University. We analysed the spatial distribution of trace metals across the study area using inverse distance weighting with standardised z-scores. Results: Mean eGFR was 117.1±15.83ml/min/1.73m2. Prevalence of low eGFR was 5% (95%CI = 3.0, 6.2), and did not vary substantially between sites. Factors associated with low eGFR included low income (<10,000 Malawian Kwacha) [OR (95%CI) = 0.16 (0.02, 1.07)]; and age [4.87 (0.39, 6.00)] per 10-year increase. Mean trace metal concentrations did not exceed permissible limits. However, some sites contained nephrotoxic metal concentrations which neared limits, including Cadmium (2.66µg/L, World Health Organisation limit 3.00µg/L). Conclusions: Reduced kidney function in the absence of known risk factors (eGFR <90 ml/min/1.73m2) was observed across our study area, however little difference in risk between sites was observed. No known nephrotoxic trace metals exceeded permissible limits, however, analyses of heavy metals concentrations in bio samples will be conducted to rule these out as risk factors for reduced kidney function in Malawi.