Methods
disability, primary retention
DISORDER, REGRESSION, SECONDARY, TUBERCULOSIS
HPTN 071 (PopART) was a three-arm CRT conducted from 2013 through 2018, in 21 urban or peri-urban communities in Zambia and South Africa [PC participants were recruited according to the following steps: (i) household census data were collected prior to PC0 to create a sampling frame; (ii) households in trial communities were randomly selected; (iii) research enumerators approached each selected household for enumeration of individual residents in the household using an electronic data capture device (EDC); (iv) from each enumerated household, one adult aged 18–44 years was randomly selected for invitation to participate in the PC, following eligibility determination; (v) if the randomly selected individual was willing to participate, an informed consent process was conducted. PC inclusion criteria included aged 18–44 years and the intention to remain in the study community for the trial duration. In contrast to facility-based studies, PopART follow-up visits were conducted in households and communities with extensive retention-focused activities. Scheduled retention activities included flexible household visit schedules in the form of household visits completed during weekday evenings and Saturdays, to reach individuals who were engaged in work or educational activities during the day [The primary objective of the current study was to evaluate characteristics associated with follow-up retention among participants enrolled at PC0. Our primary retention outcome was defined as the total number of annual visits where a participant completed a study questionnaire, with values ranging from 0 to 3. A secondary aim was to characterize retention during the study, including visit-level summaries of incomplete study visit outcomes (missed and withdrawal visits), as well as reasons for study withdrawal.PC survey data and laboratory outcomes were used in this analysis. Only data from participants enrolled at PC0 were included; participants enrolled at PC12 and PC24 were excluded from the analysis, to simplify the presentation and interpretation of results. A standardized electronic questionnaire (survey), completed at each annual round, included questions on demographic, socioeconomic, and biomedical factors. Questionnaires were administered by research enumerators who entered responses directly into the EDC which was programmed to include automated quality control steps. EDC data were uploaded in real time to the PC database managed by the HPTN data and statistical monitoring center (SCHARP). Data from laboratory test results were subsequently linked to questionnaire data in the database at SCHARP. Extensive iterative quality assurance processes were led by SCHARP with regular communication with site colleagues for resolution.Baseline variables providing a description of the research sample and hypothesized a priori to be related to retention, where data were available, were included in the analysis. Variable categories were chosen to align with those used for PopART primary and secondary analyses. We investigated the following variables: age (18–24, 25–34, 35–44); sex (male, female); marital status (married/living as married, never married, divorced/separated/widowed); nights spent away from home in the past 3 months (none, 1 to 7, 8 to 30, > 30); socioeconomic factors—education level (none to primary, partial or full secondary school, college/university), employment status (employed, student, unemployed), country-specific socioeconomic status (SES) level (low, medium, high, calculated using methods described in the supplementary materials); study factors—arm (arm A, arm B, arm C); behavioral factors—multiple sex partners in the past 12 months (yes, no), condom-less last sex (yes, no), alcohol use disorder identification test (AUDIT) score (categories low: 0–7 medium: 8–14, high: 15–40) [Combinations of longitudinal patterns of retention at the participant level were described in terms of retained visits (where a participant completed a study questionnaire) and not retained visits. Not retained visits were classified as either “missed visits” where follow-up was attempted at the next round or “withdrawal visits” where the participant was exited from the study. For each follow-up visit (PC12, PC24, PC36), we summarized the proportion of PC0 enrolled participants that were retained or had a missed or withdrawal visit, as well as reasons for study withdrawal. At PC36, all participants were considered retained or not retained, since it was the final study visit.We modeled retained visits using univariable and multivariable Poisson regression with robust Huber-White standard error estimates. All participants were assumed to have the same rate denominator of 3 possible follow-up visits. Our final multivariable model included sex as the primary exposure of interest. The following variables were hypothesized a priori to be related to retention: age, education, marital status, employment, country-specific SES, AUDIT score, and lab-confirmed HIV status. We additionally included the remaining variables (arm, nights spent away from home in the past 3 months, multiple sex partners in the past 12 months, condom-less last sex, recreational drug use, sick days taken off from work in past 3 months, disability status, self-reported HIV status and care, and self-report of ever told you have tuberculosis) if they showed a significant association (Ethical approval of the HPTN 071 (PopART) trial protocol was obtained from the ethics committees of the University of Zambia (HPTN071/PopART UNZA BREC REF: 011–11-12), Stellenbosch University (N12/11/074), and the London School of Hygiene and Tropical Medicine (6326). All participants included in this study have undergone a full informed consent process for PopART.