In our setting, there were differences in the care received by TB patients in private compared to public healthcare settings that are likely to reflect both differences in clinician practice and the case-mix managed. Private physicians were less likely to perform genotypic testing, take a sputum sample, and less likely to prescribe all four first-line medications. Patients attending private healthcare did so sooner after symptom onset, were less likely to have positive sputum specimens and certain groups did not receive assessments or commence treatment as promptly as public patients. Despite these disparities, treatment outcomes were comparable and no significant differences in health system delays to treatment commencement were found in Cox proportional hazard analyses.
The ability to distinguish patient delay from health system delays allowed us to demonstrate that in our setting public and private patients exhibited different health-seeking behaviour, with private patients attending sooner after symptom onset. Although it has been proposed that seeking medical care more promptly may indicate more severe disease and symptoms , our results were consistent with studies showing a negative association between symptom duration and smear-positivity [27, 28]. In our cohort, private patients with pulmonary involvement were less likely to have a smear-positive sputum sample than public patients, and extrapulmonary private patients were less likely to have an abnormal CXR, suggesting that private patients may present to healthcare with less severe disease. The degree to which the disparity in health-seeking behaviour reflects barriers that public patients experienced in accessing their care is unknown, and collection of more detailed qualitative information on health-seeking behaviour would be valuable.
Following healthcare attendance, several of our findings suggested that certain groups of private patients do not receive assessments or commence treatment as promptly as public patients. While it is possible these findings are due to differences in clinician practice, it may also reflect differing disease severity of the cohorts presenting to each provider type. For example, the lower likelihood of sputum examination in private patients may reflect a decreased ability to expectorate rather than clinician practice. Similarly, the fact that private extrapulmonary patients didn’t receive radiological examinations as promptly and certain groups took longer to commence treatment following an abnormal radiological result may be consistent with either 1) avoidable diagnostic delays, 2) logistical issues related to access to radiological and/or treatment, or 3) generally less severe presentations posing little risk of significant morbidity and disease transmission or greater diagnostic difficulty. While contributions from the first two possibilities cannot be discounted, the latter explanation is supported by investigation results among private patients indicating less severe disease and the fact that no significant health system delay was present overall, and treatment outcomes were comparable. From a public health perspective, the patterns of earlier presentation, less frequent smear-positivity and less severe disease also suggest a lower risk of transmission of infection.
Despite this, two of our findings, necessitate action due to the increasing incidence of multi-drug resistant TB (MDR-TB) in our setting, namely the less frequent use of genomic diagnostics and of a full complement of first-line drugs in private settings . The VTP engages closely with both public and private physicians, so educational engagement will be possible across the sector to ensure improved uptake of genotypic testing and appropriate treatment regimens.
After adjustment for covariables (listed in the comments section of Table 3), we found no significant difference in health system or laboratory delays between public and private patients using Cox proportional hazard analysis. Similar analyses in other settings have revealed treatment delays by private providers and have proposed that these may be due to “deficiencies” , poorer knowledge regarding TB management [7, 8] or a lack of “effective diagnostic tools and follow-up routines” . Although these factors may well be contributing, most previous studies did not consider important covariables, such as sputum smear status, which have previously been associated with health system delays  and that we found to be an important confounder in analyses of treatment commencement. A physician’s index of suspicion and their decision to commence treatment is inevitably influenced by their own knowledge, experience and biases, but also by factors beyond their control, including patient characteristics, manifestation, severity of disease and investigation results. These factors differed between public and private patients in our setting, and had an important influence on our results. Understanding the effect of such covariables is therefore important in any analysis of TB management.
The majority of studies comparing public and private settings have been performed in middle to high incidence settings that differ from ours. Factors associated with diagnostic and treatment delays may differ due to differing health systems, types of practitioners and health-seeking behaviour , so results are likely to be context-specific. In our setting, all TB patients, both public and private, are supervised and monitored by the VTP and TB medication is free– factors that have long been identified as leading to successful implementation of TB management . The VTP has improved engagement with both public and private sectors over time, which allows comprehensive data collection, detailed analysis of care and effective feedback of results to practitioners. Our analyses showed that programmatic indicators such as treatment completion improved in our setting over the period of observation. In other settings, including many that have high TB burdens and growing private health sectors , we recognise that such engagement may be absent, data may be unavailable, and comprehensive and meaningful assessment of healthcare may be impossible. Fostering engagement between public and private healthcare sectors should therefore be the first priority in such settings. As has been noted, “private sector involvement might not be a bad thing in itself, but… public resources must be more effectively deployed for capturing and curating data of public interest from the private sector” .
As a well-resourced setting, we are privileged to have a large, well-curated dataset, and can provide a comprehensive analysis of TB management in both sectors, including treatment outcomes. However, we acknowledge the uncertainty inherent in any statistical analyses and the limitations of making multiple statistical comparisons, and urge caution in the interpretation of presented differences. Our study is also limited by the use of retrospective surveillance data and therefore subject to the influence of factors such as changes in data collection practices over time. Furthermore, analyses of some aspects of care were impossible due to small samples of private patients. We were also unable to include several covariables in analyses that have been shown to affect health system delays in some settings, including comorbidities  and education level . However, the addition of comorbidities may further moderate disparities in diagnostic delay in our study, given the older age of private patients . Further exploration regarding health-seeking behaviour and access to care, and the inclusion of outcomes such as relapse and the extent of onward transmission are planned.