Screening for Chronic Kidney Disease (CKD) in a high risk population using a Point of Care Instrument for creatinine measurement: A community based study (The Bellville South Africa Study)
Thesis (MMedSc)--Stellenbosch University, 2017
ENGLISH ABSTRACT : Chronic kidney disease (CKD) is described as abnormal kidney function in which one third is lost over a period of 3 months and is a global epidemic with a particularly concentrated incidence within developing countries, such as Sub-Sahara Africa (SSA). Health facilities in SSA are limited due to lack of funding and a dearth in disease and medical knowledge. This coupled with the high incidence of both communicable and non-communicable diseases makes for an ideal environment for the implementation of Point-of-Care Testing (POCT), defined as an analytical test that is performed near the patient, delivering results in real time without the need for a conventional laboratory. CKD POCT involves the measurement of creatinine in capillary whole blood samples in order to determine the estimated glomerular filtration rate (eGFR) of patients in order to stage their CKD status from stage 1-6. This study aimed to bridge the gap in knowledge with regard to cut-offs of creatinine levels and eGFR values when screening a mixed ancestry populations. Currently there is only documented and standardized cut-offs for Caucasian and African American populations. This study looked at the African mixed ancestry population and acts as a starting point for standardizing POCT cut-offs for other international mixed ancestry populations. 103 participants were recruited from the Bellville South community, Cape Town, South Africa. The study was a comparative study that was designed to evaluate the Nova Statsensor® point of care instrument for the measurement of creatinine for the detection of CKD in adult mixed ancestry subjects from the Bellville South Community in South Africa. Secondary objectives included (1) the prevalence of CKD based on the results of the instrument, and (2) the correlation between the Nova Statsensor®, and the central laboratory creatinine values (IDMS traceable). Ancillary objectives of the study were to evaluate the technical quality of POC testing for creatinine in a community setting, as well as the evaluation of the cost implications when introducing this form of POCT into a primary care setting. The study found that the Nova Statsensor® in this study had a sensitivity of 66.7% and a specificity of 100%, displaying excellent diagnostic accuracy. It was found that the device displayed negative proportional bias which may lead to future CKD patients being misdiagnosed as healthy within screening programmes. The prevalence was found to be 2.9% within this mixed ancestry population. The device was user friendly and requires a small sample volume, however it is costly to implement. The laboratory evaluation study found that the Nova Statsensor® creatinine meter produced a direct creatinine concentration comparison that was less than expected, possibly due to creatinine levels depending on several factors which include muscle mass, obesity, gender, and age and having a wide reference interval. Thus highlighting the importance of the use of the equations to calculate eGFR in CKD screening in order to obtain the CKD staging results which displayed better correlation to the reference method, compared to creatinine measurement alone. The device was comparable to the reference method when performance was measured based on CKD staging through the calculation of the MDRD equation.
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