Evaluation of a social protection policy on tuberculosis treatment outcomes: A prospective cohort study

Background Tuberculosis (TB) still represents a major public health problem in Latin America, with low success and high default rates. Poor adherence represents a major threat for TB control and promotes emergence of drug-resistant TB. Expanding social protection programs could have a substantial effect on the global burden of TB; however, there is little evidence to evaluate the outcomes of socioeconomic support interventions. This study evaluated the effect of a conditional cash transfer (CCT) policy on treatment success and default rates in a prospective cohort of socioeconomically disadvantaged patients. Methods and findings Data were collected on adult patients with first diagnosis of pulmonary TB starting treatment in public healthcare facilities (HCFs) from 16 health departments with high TB burden in Buenos Aires who were followed until treatment completion or abandonment. The main exposure of interest was the registration to receive the CCT. Other covariates, such as sociodemographic and clinical variables and HCFs’ characteristics usually associated with treatment adherence and outcomes, were also considered in the analysis. We used hierarchical models, propensity score (PS) matching, and inverse probability weighting (IPW) to estimate treatment effects, adjusting for individual and health system confounders. Of 941 patients with known CCT status, 377 registered for the program showed significantly higher success rates (82% versus 69%) and lower default rates (11% versus 20%). After controlling for individual and system characteristics and modality of treatment, odds ratio (OR) for success was 2.9 (95% CI 2, 4.3, P < 0.001) and default was 0.36 (95% CI 0.23, 0.57, P < 0.001). As this is an observational study evaluating an intervention not randomly assigned, there might be some unmeasured residual confounding. Although it is possible that a small number of patients was not registered into the program because they were deemed not eligible, the majority of patients fulfilled the requirements and were not registered because of different reasons. Since the information on the CCT was collected at the end of the study, we do not know the exact timing for when each patient was registered for the program. Conclusions The CCT appears to be a valuable health policy intervention to improve TB treatment outcomes. Incorporating these interventions as established policies may have a considerable effect on the control of TB in similar high-burden areas.


Introduction
Background/rationale 2 Explain the scientific background and rationale for the investigation being reported The Introduction explains the scientific background and rationale for the investigation Objectives 3 State specific objectives, including any prespecified hypotheses Objectives are stated in the last two paragraph of the Introduction.

Study design 4
Present key elements of study design early in the paper The study design is stated in the Title, the Abstract and the first paragraph of Methods. Setting 5 Describe the setting, locations, and relevant dates, including periods of recruitment, exposure, follow-up, and data collection Setting and location is specified in paragraph 1 of the Methods section. The dates of data collection are described in paragraph 1 of the Results section Periods of recruitment, exposure and follow-up are explained in the Procedure section in paragraph 4 of the Methods. Participants 6 (a) Give the eligibility criteria, and the sources and methods of selection of participants. Describe methods of follow-up The section Study design and participants gives this information in paragraph 1 of Methods.
(b) For matched studies, give matching criteria and number of exposed and unexposed Number of exposed and unexposed and variable balance achieved by the Propensity score matching are included in paragraph 10 and 11 of Results.

Variables 7
Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable The section Variable and outcomes gives these definitions in paragraph 6, 7 and 8 of the Methods section.
Data sources/ measurement 8* For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe comparability of assessment methods if there is more than one group Explained in paragraph 5 of Methods under the section Procedures.

Bias 9
Describe any efforts to address potential sources of bias In the section Statistical Analysis we explained how we addressed potential bias (paragraph 11 of Methods) Study size 10 Explain how the study size was arrived at In paragraph 9 of Methods, under the Statistical Analysis we explained how the study size was arrived. Quantitative variables 11 Explain how quantitative variables were handled in the analyses. If applicable, describe which groupings were chosen and why The detailed analyses are explained in the section Statistical Analysis.
Statistical methods 12 (a) Describe all statistical methods, including those used to control for confounding The detailed analyses are explained in the section Statistical Analysis.
Please also see S1 Propensity Score & IPW adjustment. (b) Describe any methods used to examine subgroups and interactions Please also see S1 Propensity Score & IPW adjustment.
(c) Explain how missing data were addressed We had a few patients with missing information on the exposure (2.18%) and outcomes (1,6%). They were not included in the analysis. See  Other analyses 17 Report other analyses done-eg analyses of subgroups and interactions, and sensitivity analyses Pleases see Statistical analysis and supplementary material (S1 Propensity Score & IPW adjustment).

Discussion
Key results

18
Summarise key results with reference to study objectives First paragraph of the Discussion.

Limitations 19
Discuss limitations of the study, taking into account sources of potential bias or imprecision. Discuss both direction and magnitude of any potential bias In the Discussion section (paragraph 9) Interpretation 20 Give a cautious overall interpretation of results considering objectives, limitations, multiplicity of analyses, results from similar studies, and other relevant evidence All this items are described in the Discussion section.

Generalisability 21
Discuss the generalisability (external validity) of the study results Last paragraph of Discussion section.

Other information
Funding 22 Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on which the present article is based