Study setting
We implemented a TB ACF program based at a routine HCT and TB screening center in a transportation hub in central Johannesburg, South Africa from August 2011 to April 2012. The screening center was located in a space within the transport hub that was easily accessible to commuters and transport workers. The center served approximately 100,000 short-distance commuters daily who were traveling within greater Johannesburg and near-by towns or informal settlements [12]. During the study period, approximately 2,000 drivers operated daily from the transport center.
The active case finding model
Prior to implementation of the ACF model, we obtained stakeholder buy-in from the transport center management, the 11 minibus associations operating within the center, and nearby public health clinics. In addition, we conducted focus group discussions with drivers to explore their perceptions regarding TB ACF and to identify ways to encourage TB screening. The formative interviews identified three key issues: (1) TB screening should be decoupled from HIV testing because drivers unwilling to undergo HCT were interested in TB screening, (2) TB screening needed to be brought to the driver, and (3) the total time required for the process needed to be short (<15 minutes).
We designed a program around these parameters. We provided screening in portable gazebos in minibus parking bays, limited the recipients of this service to transport workers to keep waiting queues short (routine HCT and TB screening was still available at the fixed center site), and made HIV testing optional and available at the end of the TB screening. The ACF team was comprised of two nurses who led a team of four trained lay counsellors. This team size allowed for screening 50 or more drivers during the main downtime in the drivers’ day, between 9 am and 3 pm, each in less than 15 minutes. Drivers were mobilized for screening through a combination of minibus association meetings, distribution of pamphlets, daily individual and group outreach, and provision of vouchers for food or fuel (valued at ZAR50/US$6).
TB screening was performed using the WHO four symptom tool (any duration of cough, fever, night sweats, or weight loss) [13]. In order to assess the sensitivity of the symptom screen in this population, a single spot sputum sample was collected from all drivers and sent to a single commercial laboratory for fluorescence microscopy and culture on mycobacterial growth indicator tubes (MGIT, Becton, Dickenson, & Company, New Jersey, USA).
Cultures that were positive for Mycobacteria species were identified as M tuberculosis or a non-tuberculosis mycobacteria species using Hain GenoType MTBDRplus and the Hain GenoType Mycobacterium CM (Hain Lifescience GmbH, Germany). Positive cultures were tested for drug susceptibility to first-line TB drugs using the Becton Dickinson BACTEC MGIT SIRE system (Becton-Dickinson, Franklin Lakes, USA). Participants were contacted telephonically to collect their TB microscopy results and when culture results were available. Individuals who were positive for TB were educated on the meaning of the test result and importance of treatment, referred to a health facility, and followed-up to ascertain entry into TB care.
All drivers were also offered HCT, but were not specifically required to undergo HCT to be screened for TB. HIV testing was done on-site using a rapid lateral flow assay (Determine® HIV-1/2, Alere, Massachusetts, USA) and, if positive, a confirmatory test was done using a different rapid lateral flow assay (Unigold™ Recombigen® HIV, Bray, Ireland). In addition, blood pressure screening and spot capillary blood glucose testing were offered to all drivers (Roche Accucheck® Active Test Kit, Basel, Switzerland).
Our goal was to screen 80% (1,600) of the minibus drivers at the transport center. We planned on a three month project period given the screening team capacity and goal. However, we extended screening an additional 5 months (total 8 months) due to low uptake.
Study design
We performed a cross-sectional assessment. All participants were administered a brief questionnaire that included questions on demographics, working conditions, TB and HIV testing history, TB knowledge, attitudes and beliefs towards seeking health care, and current symptoms (any duration of cough, fever, night sweats, or weight loss). All participants completed a signed informed consent process prior to study procedures. The study was approved by the University of the Witwatersrand Human Subjects Ethics Committee.
Analysis
We defined uptake by the total number of drivers screened as a proportion of the total population of drivers working at the transport center. Analyses of TB diagnosis were restricted to definite TB, defined as a sputum culture positive for M. tuberculosis. We excluded smear microscopy positive, culture negative TB from the analysis because of the limited specificity of a single sputum sample. We defined elevated random glucose as a random capillary blood glucose assay result of greater than 7.8 mmol/L [14]. We used logistic regression to assess for associations between undiagnosed prevalent TB and individual characteristics including sex, age, HIV status, duration of work, work hours, incarceration history, glucose level, and current smoking status. Incarceration history was defined as a participant reporting having spent at least one night in a police holding cell or in a correctional service facility. Multivariable logistic regression with backward elimination techniques was used for the final model. Retention of study variables was based upon a Chi-squared p-value of 0.05 or less.