Assessing the completeness and accuracy of South African National Laboratory CD4 and viral load data: a cross-sectional study

Abstract

ObjectiveTo assess the accuracy of the South African National Health Laboratory Services (NHLS) corporate data warehouse (CDW) using a novel data cross-matching method.MethodsAdults (≥18 years) on antiretroviral therapy (ART) who visited a hospital-based HIV clinic in Durban from March to June 2012 were included. We matched patient identifiers, CD4 and viral load (VL) records from the HIV clinic’s electronic record with the NHLS CDW according to a set of matching criteria for patient identifiers, test values and test dates. We calculated the matching rates for patient identifiers, CD4 and VL records, and an overall matching rate.ResultsNHLS returned records for 3498 (89.6%) of the 3906 individuals requested. Using our computer algorithm, we confidently matched 3278 patients (83.9% of the total request). Considering less than confident matches as well, and then manually reviewing questionable matches using only patient identifiers, only nine (0.3% of records returned by NHLS) of the suggested matches were judged incorrect.ConclusionsWe developed a data cross-matching method to evaluate national laboratory data and were able to match almost 9 of 10 patients with data we expected to find in the NHLS CDW. We found few questionable matches, suggesting that manual review of records returned was not essential. As the number of patients initiating ART in South Africa grows, maintaining a comprehensive and accurate national data repository is of critical importance, since it may serve as a valuable tool to evaluate the effectiveness of the country’s HIV care system. This study helps validate the use of NHLS CDW data in future research on South Africa’s HIV care system and may inform analyses in similar settings with national laboratory systems.

Using national laboratory data to assess cumulative frequency of linkage after transfer to community‐based HIV clinics in South Africa

“…This estimate is lower and may be more accurate than our previous estimate of 82%, which was based on patient self-report of re-linkage and validation of an initial clinic visit for a subset of patients [28]. We have previously assessed the completeness and accuracy of the NHLS CDW by matching patient identifiers and pretransfer CD4 and VL test results from the McCord Hospital dataset to data returned by NHLS; we reported that NHLS did not find a match for 10% of the patients in the transfer cohort [23], which may have also affected the ability to match post-transfer laboratories for a small proportion of patients. It is also possible that patients in care post-transfer were classified as "not re-linked" because they were not receiving guideline concordant CD4 count and VL monitoring at their new clinical site.…”

“…As we reported previously, after extensive efforts assessing the quality of subject matching for data provided by the NHLS, we determined that 99.7% of the individuals were correctly matched . Based on this result, we previously recommended that matches from NHLS be accepted without extensive review, and have followed this approach in the current analysis . Patients who had at least one NHLS record, whether CD4 count or VL, within approximately three years after the end of the transfer period were considered re‐linked.…”

“…All data, including patient identifiers, name of facility, date of sample and tests requested, are sent to the CDW and are captured electronically by the NHLS information system in real time. We have previously evaluated the completeness and accuracy of the NHLS CDW using a novel data crossmatching method .…”

“…Data from the National Health Laboratory Service (NHLS), South Africa's repository for all public sector laboratory measurements, have previously been used to evaluate the effectiveness of certain government‐funded HIV‐programmes , to identify patterns of the country's TB epidemic , and to determine cancer incidence rates among HIV‐infected patients . While we have previously assessed the completeness and accuracy of the NHLS Corporate Data Warehouse (CDW) and have validated the NHLS CDW as a reliable data source , the use of NHLS data to evaluate the outcome of patient transfers has been limited . Despite that, it has been shown to be an effective tool for more accurately estimating lost to follow‐up for women transferring to postpartum care .…”

Cancer in HIV-positive and HIV-negative adolescents and young adults in South Africa: a cross-sectional study

“…The data from the CDW has been evaluated for completeness and accuracy and validated as a good source of data for research on HIV in South Africa. [21]…”