Towards cost-effective tuberculosis control in the Western Cape of South Africa: intervention study involving lay health workers on agricultural farms

BACKGROUND At the request of the farming community, the local public health authority in a tuberculosis (TB) high-burdened area implemented a farm-based lay health worker (LHW) project focusing on TB control. This project achieved a significantly better (15%) treatment adherence rate among adult TB patients. Management was keen to expand the intervention, but non-randomised sampling methodology had been used and could have resulted in an over-estimation of results. A more rigorous research design was requested to evaluate this project before replication; therefore this study. OBJECTIVE To evaluate the effectiveness of an LHW intervention within a primary health care (PHC) framework, aimed at improving TB case finding and case holding among permanent farm dwellers, to explore the perceptions of the different stakeholders, and do a cost-effectiveness analysis, in order to contribute to TB control in South Africa. METHODS This LHW model was rigorously evaluated using an unblinded, pragmatic cluster randomised control trial (RCT), while qualitative research evaluated the perceptions of the stakeholders, and a cost-effectiveness analysis established the costeffectiveness of LHWs in conjunction with the standard TB control programme. RESULTS The successful treatment completion rate in the new smear-positive (NSP) adult TB patients was 18.7% higher (P = 0.042, 95% CI 0.9%-36.4%) on farms in the intervention group than in the control group. The treatment interruption rate was 4% on intervention farms, compared to 26% on control farms. In the intervention group 8% more (P = 0.2671) farms increased their adult NSP TB case finding, compared to farms in the control group. A cost-effectiveness analysis showed a potential saving of 59% for the public health sector in direct staff costs for clinic-based directly observed treatment of TB patients living on farms. Qualitative studies found that farmers remained positive; however, they desired recognition from the public health sector. LHWs, 95% of whom were women, were grateful for the opportunity, but feared becoming overburdened. Among temporary farm workers the NSP TB point prevalence was 6/356 (1.7%), and the total TB point prevalence was 10/356 (2.8%). CONCLUSIONS Although the focus of this study was on permanent farm labour there has been a subsequent significant change in the labour structure on farms, resulting in a shift towards temporary employment. This will require a separate study. However, the research conducted on permanent farm dwellers shows convincingly that resident, trained LHWs on farms, in conjunction with the public health sector, have the potential to substantially enhance TB control activities on farms and in similar community settings. Pivotal for success are political commitment, a dedicated project champion, an adequate budget and adoption by the health service system and other stakeholders.