Cindynics applied to Nephrology, A Framework to StandardizeEarly Detection and Management of Kidney Diseases in Sub-Saharan Africa.

Abstract Background: Dialysis is not funded in the Cameroonian private sector where the prevalence of chronic kidney disease is unknown. Early detection and management of kidney disease must be optimal in sub-Saharan private hospitals where dialysis is not affordable. Lack of routine estimation of the glomerular filtration rate and the variability of serum creatinine reference values between laboratories are major barriers to early detection and treatment for kidney diseases. This must change. We aimed to explore the potential of cindynics, "the science of danger" as a framework to study and prevent kidney disease in sub-Saharan Africa. Methods: We conducted a retrospective study from January 1 2019 to December 31 2021, examining the distribution of reported serum creatinine values in one laboratory, which uses a standardized colorimetric-kinetic Jaffe method and CKD-EPI (2009) equation to estimate the glomerular filtration rate. Reference serum creatinine values were between 0.9 and 1.3 mg/dl for the entire test population. Findings: 7028 measurements were analyzed. The mean and median serum creatinine values were 1.2 mg/dl (SD 1.1) and 1.10 mg/dl (range 0.21 - 34 mg/dl) respectively. eGFR ranged from 1 to 238.6 ml/min per 1.73m2 with a mean value of 70.2 ml/min per 1.73m2. Serum creatinine was significantly different between females and males (p <0,005) above 18 years but not below (p=0,5). Mean eGFR was slightly higher in females above 18 years: 72.6 ml/min per 1.73m2 (SD 26,6) vs 68.3 ml/min per 1.73m2 (SD 28,8) in males. In the subgroup with normal ranges of serum creatinine, normal eGFRs (above 90 ml/min per 1.73m2) were present 8.6% in females and 43.7% in males. In this same subgroup, eGFRs below 60 ml/min per 1.73m2 were present 13.4% in females vs 0.1% in males. Interpretation and Conclusion: Chronic kidney disease, because of no immediate and apparent consequences, was here considered as "the danger". Most of the participants particularly females, had both normal serum creatinine values according to the laboratory and abnormal eGFRs. No unique serum creatinine reference values should be performed in the entire test population. "Reference values" are the 4th cindynics dimension. Applied to nephrology by physicians and health policy makers, cindynics is a comprehensive and personalized method implemented to standardize creatinine with low variability across laboratories, to estimate the glomerular filtration rate routinely in all the Cameroonian settings and then contribute more epidemiological data in Central sub-Saharan Africa. Key words: cindynics, kidney disease prevention, bionephrology, serum creatinine reference values, eGFR, CARE (cartographie rénale in French).