Epidemiology of chronic kidney disease in KwaZulu-Natal: evaluation of risk factors, complications and diagnostic methods.
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Date
2017
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Abstract
Chronic kidney disease (CKD) is associated with increased morbidity and mortality as well
as costly renal replacement therapy. The aim was to determine risk factors and complications
that contribute to morbidity as well as a suitable diagnostic detection method for CKD.
Methods
Observational studies were done at 2 hospitals. To assess risk factors, 283 patients were
included at the Durban site, and sub-studies undertaken within this sample for CKD
complications, while 302 patients were studied at the Empangeni outreach site. To evaluate
predictive performance of estimated glomerular filtration rate (eGFR), data from 148 patients
were analysed. A further 76 patients were recruited, to develop an African equation. Cockcroft Gault, Modified Diet in Renal Disease and CKD Epidemiology Collaboration eGFR equations were compared with technicium-99-mdiethylenetriaminepentaacetic acid (99mTc-DTPA)-GFR
as the gold standard. Body composition was assessed by anthropometry and dual energy X-ray
absorptiometry. Data were analysed with STATA.
Results
The commonest CKD risk factors were hypertension (75%), diabetes (29%) and human
immunodeficiency virus (HIV) infection (24%), with HIV commoner at the outreach site
(28.5% vs 19.8%). Over 80% of females and ∼60% males were overweight/obese overall;
however, clinical cardiovascular disease was commoner in Durban (28% vs 5%).
Complications were observed in early CKD; prevalence increased as eGFR declined from ≥90
ml/min/1.73m2 to <30 ml/min/1.73m2: hyperuricaemia increased from 17% to 74%, metabolic
acidosis (11.6% to 72.7%), anaemia (2.9% to 69.7%), hyperphosphataemia (10.1% to 48.5%),
all p<0.001, respectively, and hypocalcaemia from 1.5% to 18.2% (p=0.003). Lower GFR
levels were also associated with lower serum albumin levels, and lower whole body as well as
regional lean mass and fat mass in males. A further observation at GFR <30 ml/min/1.73m2
was that eGFR underestimated 99mTc-DTPA-GFR in African patients. Prediction of 99mTc DTPA-GFR was also poor at GFR levels ≥60 ml/min/1.73m2, with eGFR overestimating
99mTc-DTPA-GFR. An eGFR equation developed in African patients resulted in significantly
better GFR prediction and showed the lowest bias, highest precision as well as accuracy.
Conclusion
Efforts are needed to enable non-nephrologists to manage CKD risk factors and complications.
Prediction of GFR may be substantially improved by using an equation developed in Africans.
Description
Doctoral Degree. University of KwaZulu-Natal, Durban.