RenalTWO - Advancing chronic kidney disease (CKD) epidemiology and non-communicable disease research in semi-rural Tanzania through longitudinal risk assessment

Chronic kidney disease (CKD), diabetes, and hypertension are major public health challenges in sub-Saharan Africa (SSA) all interlinked with each other, yet data on their burden, risk factors, and progression remain scarce. The RenalTWO project, launched on June 21. 2023, aims to address this gap by recruiting patients from the Bagamoyo District Hospital (BDH) outpatient clinic and two adjacent dispensaries, representing a semi-rural SSA setting. The project investigates CKD and non-communicable diseases (NCDs) using internationally recognized diagnostic methods and classification guidelines, contributing to improved diagnostics and patient management.

RenalTWO assesses the CKD risk signature by evaluating a wide range of biomarkers, anthropometrics, and in-depth questionnaires covering medical history, socioeconomics, nutrition, lifestyle, and physical activity. In addition to traditional cardiovascular disease (CVDs) risk factors, the project explores non-traditional CKD risk factors such as endemic infectious diseases and exposure to environmental toxins, particularly those linked to small-scale agriculture in low- and middle-income countries (LMICs). Physical activity is objectively measured using step-count devices.

Unlike many CKD studies, RenalTWO includes a confirmation visit after ≥3 months, addressing a common limitation in CKD epidemiology where single-time assessments may overestimate prevalence. This approach makes RenalTWO likely the first study to properly confirm CKD diagnoses in an unselected primary care population form SSA.

With its third assessment the 1-year follow-up, the cohort will provide even more evidence on the on-set of CKD and its CVD risk factors  and their chronicity.

The project integrates clinical, epidemiological, and laboratory data to enhance the understanding of CKD and its interplay with NCDs. It includes DNA extraction and biobank storage to investigate genetic variants associated with CKD, particularly APOL1 high risk gen variants sofar only studied in Southern and West African populations from SSA.

We hypothesize that the prevalence of CKD in SSA, and Tanzania in particular, is lower than reported despite an increasing risk burden, and that the risk for developing CKD encompasses factors beyond classic cvRFs.

Our General Aims are to:
(i) Establish guideline conform prevalence data of CKD and its major cvRFs and non-traditional risk factors.
(ii) Prospectively define the incidence of cardiovascular- and non-traditional risk factors of CKD.
(iii) Define the prevalence of APOL1 gene variants
Integrating data from (i), (ii), and (iii) we then aim to:
(iv) interrogate the linked interaction over time between risk factors and development of CKD, thus developing a SSA-specific risk model.

RenalTWO has established a clinic at BDH, trained a local team—including a medical doctor, nutritionist, lab technicians, study nurses, and recruiters—to ensure high-quality data collection and patient engagement. Approximately 1200 patients have been enrolled at BDH and 300 at dispensaries in Yombo and Fukayosi, ensuring representation from different healthcare settings.

RenalTWO aims to generate high-quality epidemiological data to improve CKD screening strategies, refine prevalence estimates for SSA, and inform national and regional health policies. Future efforts include cohort expansion and long-term follow-ups in 2026 for state transition analysis, pending funding, to better understand disease trajectories and develop effective public health interventions to mitigate the NCD epidemic in LMICs.

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