Prevalence and risk factors for chronic kidney disease of unknown cause in Malawi: a cross-sectional analysis in a rural and urban population

Hamilton, S. A., Nakanga, W. P., Prynn, J. E., Crampin, A. C. , Fecht, D., Vineis, P., Caplin, B., Pearce, N. and Nyirenda, M. J. (2020) Prevalence and risk factors for chronic kidney disease of unknown cause in Malawi: a cross-sectional analysis in a rural and urban population. BMC Nephrology, 21, 387. (doi: 10.1186/s12882-020-02034-x) (PMID:32894093) (PMCID:PMC7487679)

Abstract

Background: An epidemic of chronic kidney disease of unknown cause (CKDu) is occurring in rural communities in tropical regions of low-and middle-income countries in South America and India. Little information is available from Southern African countries which have similar climatic and occupational characteristics to CKDu-endemic countries. We investigated whether CKDu is prevalent in Malawi and identified its potential risk factors in this setting. Methods: We conducted a cross-sectional study from January–August 2018 collecting bio samples and anthropometric data in two Malawian populations. The sample comprised adults > 18 years (n = 821) without diabetes, hypertension, and proteinuria. Estimates of glomerular filtration rate (eGFR) were calculated using the CKD-EPI equation. Linear and logistic regression models were applied with potential risk factors, to estimate risk of reduced eGFR. Results: The mean eGFR was 117.1 ± 16.0 ml/min per 1.73m2 and the mean participant age was 33.5 ± 12.7 years. The prevalence of eGFR< 60 was 0.2% (95% confidence interval (95% CI) 0.1, 0.9); the prevalence of eGFR< 90 was 5% (95% CI =3.2, 6.3). We observed a higher prevalence in the rural population (5% (3.6, 7.8)), versus urban (3% (1.4, 6.7)). Age and BMI were associated with reduced eGFR< 90 [Odds ratio (OR) (95%CI) =3.59 (2.58, 5.21) per ten-year increment]; [OR (95%CI) =2.01 (1.27, 3.43) per 5 kg/m2 increment] respectively. No increased risk of eGFR < 90 was observed for rural participants [OR (95%CI) =1.75 (0.50, 6.30)]. Conclusions: Reduced kidney function consistent with the definition of CKDu is not common in the areas of Malawi sampled, compared to that observed in other tropical or sub-tropical countries in Central America and South Asia. Reduced eGFR< 90 was related to age, BMI, and was more common in rural areas. These findings are important as they contradict some current hypothesis that CKDu is endemic across tropical and sub-tropical countries. This study has enabled standardized comparisons of impaired kidney function between and within tropical/subtropical regions of the world and will help form the basis for further etiological research, surveillance strategies, and the implementation and evaluation of interventions.

• Item Type: Articles
• Additional Information: The results reported herein correspond to specific aims of grant MRC GCRF Foundation Grant MR/P02386X/1 which funded the cross-sectional study data collection and laboratory analyses in the United Kingdom. This work was also supported by grants from the Medical Research Council – Public Health England PhD studentship funding, and the Imperial College Medical Research Council Supplement Scheme #63.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Crampin, Professor Mia
• Authors: Hamilton, S. A., Nakanga, W. P., Prynn, J. E., Crampin, A. C., Fecht, D., Vineis, P., Caplin, B., Pearce, N., and Nyirenda, M. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
• Journal Name: BMC Nephrology
• Publisher: BioMed Central
• ISSN: 1471-2369
• ISSN (Online): 1471-2369
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in BMC Nephrology 21: 387
• Publisher Policy: Reproduced under a Creative Commons License