Using routinely collected laboratory data to identify high rifampicin-resistant tuberculosis burden communities in the Western Cape Province, South Africa : a retrospective spatiotemporal analysis
Date
2018
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Abstract
Background:
South Africa has the highest tuberculosis incidence globally (781/100,000), with an estimated
4.3% of cases being rifampicin resistant (RR). Control and elimination strategies will
require detailed spatial information to understand where drug-resistant We retrospectively identified cases of microbiologically confirmed tuberculosis and RRtuberculosis
from all biological samples submitted for tuberculosis testing (n = 2,219,891) to
the Western Cape National Health Laboratory Services (NHLS) between January 1, 2008,
and June 30, 2013. Because the NHLS database lacks unique patient identifiers, we performed
a series of record-linking processes to match specimen records to individual
patients. We counted an individual as having a single disease episode if their positive samples
came from within two years of each other. Cases were aggregated by clinic location (n
= 302) to estimate the percentage of tuberculosis cases with rifampicin resistance per clinic.
We used inverse distance weighting (IDW) to produce heatmaps of the RR-tuberculosis percentage
across the province. Regression was used to estimate annual changes in the RR- tuberculosis exists tuberculosis percentage by clinic, and estimated average size and direction of change was
mapped. We identified 799,779 individuals who had specimens submitted from mappable
clinics for testing, of whom 222,735 (27.8%) had microbiologically confirmed tuberculosis.
The study population was 43% female, the median age was 36 years (IQR 27±44), and
10,255 (4.6%, 95% CI: 4.6±4.7) cases had documented rifampicin resistance. Among individuals
with microbiologically confirmed tuberculosis, 8,947 (4.0%) had more than one disease
episode during the study period. The percentage of tuberculosis cases with rifampicin
resistance documented among these individuals was 11.4% (95% CI: 10.7±12.0). Overall,
the percentage of tuberculosis cases that were RR-tuberculosis was spatially heterogeneous,
ranging from 0% to 25% across the province. Our maps reveal significant yearly fluctuations
in RR-tuberculosis percentages at several locations. Additionally, the directions of
change over time in RR-tuberculosis percentage were not uniform. The main limitation of
this study is the lack of unique patient identifiers in the NHLS database, rendering findings to
be estimates reliant on the accuracy of the person-matching algorithm.
Conclusions: Our maps reveal striking spatial and temporal heterogeneity in RR-tuberculosis percentages
across this province. We demonstrate the potential to monitor RR-tuberculosis spatially and
temporally with routinely collected laboratory data, enabling improved resource targeting
and more rapid locally appropriate interventions.
and why it persists in those communities. We demonstrate a method to enable drug-resistant
tuberculosis monitoring by identifying high-burden communities in the Western Cape
Province using routinely collected laboratory data.
Methods and findings:
Description
CITATION: McIntosh, A. I., et al. 2018. Using routinely collected laboratory data to identify high rifampicin-resistant tuberculosis burden communities in the Western Cape Province, South Africa : a retrospective spatiotemporal analysis. PLoS Medicine, 15(8):e1002638, doi:10.1371/journal.pmed.1002638.
The original publication is available at https://journals.plos.org/plosmedicine
The original publication is available at https://journals.plos.org/plosmedicine
Keywords
Tuberculosis -- Drug resistance, Rifampin, Spatial analysis (Statistics)
Citation
McIntosh, A. I., et al. 2018. Using routinely collected laboratory data to identify high rifampicin-resistant tuberculosis burden communities in the Western Cape Province, South Africa : a retrospective spatiotemporal analysis. PLoS Medicine, 15(8):e1002638, doi:10.1371/journal.pmed.1002638