The association between renal sonography and renal function in chronic kidney disease at Inkosi Albert Luthuli Chief Hospital: a retrospective descriptive study.
Frank, Astley Gershwyn.
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Background Non-communicable diseases (NCDs) are rapidly emerging as a major cause of chronic kidney disease (CKD) in Africa with a reported prevalence of 10.7% locally. At current, few high-quality studies assessing the epidemiology of CKD in South Africa have been published. Alarmingly, CKD is now at epidemic proportions and is a leading cause of mortality with significant cost implications. This study aims to investigate economic means of predicting renal function in CKD by exploring the association between estimated glomerular filtration rate (eGFR) and renal morphology evaluated by ultrasound (US). Methods This is a retrospective descriptive chart review conducted at the Department of Nephrology, Inkosi Albert Luthuli Central Hospital (IALCH), Cato Manor, Kwa-Zulu Natal from January 2016 to December 2016. A total of 455 patients who had met the Kidney Disease Improving Global Outcomes (KDIGO) definition of CKD with eGFR (MDRD) and renal US performed were included. Demographic, clinical, laboratory and renal morphological data (renal length (RL), increased echogenicity (IE) and loss of corticomedullary differentiation (LCMD)) on US were collected and analyzed with SPSS software (v. 27). Associations between eGFR, parameters on US and CKD risk factors were determined using logistic regression analysis. Results Black Africans 75.2% (n.342) and females 56.9% (n.259) predominated the sample. Whilst, Indians, Whites and Coloureds comprised of 20.4%, 2.42% and 1.98% of the study respectively. The median age was 45.8 ± 14.3 years. Hypertension 34.9%, diabetes 26.8%, HIV 27.5% and glomerulonephritis 9.89% were the four most frequently reported risk factors, of which Black Africans comprised more than 50% of cases (p <0.001). A significant proportion of patients 65.7% (n.307) had end-stage renal disease with a median eGFR of 14.4 ± 12.8ml/min/1.73m2 (p <0.001). The median right and left RL were short at 8.49 ± 2.16cm and 8.60 ± 2.20cm respectively. Black Africans were also found to have significantly shorter RLs and lower eGFRs (p <0.001). The dual effect of IE and LCMD predisposed to significantly shorter RLs and lower eGFRs than in the presence of one or no abnormality on US (p <0.001). IE [-9.29 OR; 95% CI (-13.8 - -4.77); p <0.001] and RL [right: 5.02 OR; 95% CI (3.44 – 6.60); p 0.04; left: 5.11 OR; 95% CI (3.56 – 6.66); p 0.04] were found to be significant predictors of eGFR. HIV was the only risk factor found to be negatively associated with all determined measures of renal function, as well as the sole predictor of IE [2.31 OR; 95% CI (0.17 - 3.15); p 0.02]. Conclusion The CKD epidemic is driven by the complex interplay between communicable (HIV) and NCDs (HPT/DM) and has emerged as an important public health and economic threat in Southern Africa. Africans are most vulnerable presenting with an advanced and accelerated disease course. GFR determination and US are inexpensive means of determining renal function particularly in resource limited settings. IE and RL are surrogate markers of renal function with an increased echogenic pattern being most predictive of renal dysfunction in CKD, particularly in HIV.