Discussion
DISEASE PROGRESSION
In this rural South African area with high HIV prevalence and where HBHCT campaigns were implemented in the context of the UTT TasP trial, linkage to care was suboptimal. In response to this, a linkage to care intervention was nested within the study 14 months after implementation. Despite the fact that not all eligible individals received the intervention, we showed that repeat referral to care through phone calls and home visits was effective in improving time to linkage to care amongst individuals who were offered the intervention. This result is consistent with previous studies conducted in southern Africa showing the effect of re-referral by lay counsellors visiting people at their home to increase rates of linkage to HIV care after a first home-based referral through HBHCT [Entry into HIV care and initiating a treatment lead to significant changes in daily life, and people may need time to process and accept their HIV status and link to HIV care [Another interesting result is that the effect of the intervention did not differ according to sex, age, educational level, or HIV care status at referral, suggesting that a simple re-referral intervention may be effective for various population groups. The other factors associated with linkage-to-care were discussed in a previous paper [Yet, fidelity of the intervention implementation was not optimal, with difficulties to implement the intervention timeously. First, it is essential to note that the linkage-to-care intervention targeted both people not in care at referral (on which this paper focused) and those in care in a DoH clinic at referral but who did not go to a TasP trial clinic; thus, while this paper explores only fidelity of the intervention among people not in care at referral, the workload for fieldworkers was more important. Second, the linkage-to-care was implemented only 14 months after the start of the trial, and in practice, the linkage-to-care team worked from lists not generated in real time.. The fact that there was delayed introduction of the linkage-to-care interventions could partially explain the low probability of contact or re-referral within six months of receiving an HIV test which were the outcomes used to assess fidelity in this study. For future implementation of such interventions, digital health systems need to be put in place to ensure that individuals eligible for tracking are identified in real-time. For example, SMS alerts could be sent to health care workers to prompt follow-up visits if patients do not present at a clinic after HBHCT [Furthermore, perhaps a three-month wait before tracking those not linked to care may have been too long, considering the very high mobility in this setting. Identifying and targeting the “non-linkers” requiring re-referral to care will be crucial for reaching 95-95-95 UNAIDS targets. However, we can expect this task to be highly complex due to the variety of HIV testing strategies (clinic- and community-based), cyclical engagement and disengagement from care, and the sub-optimal system for identifying patients who had not linked to care or had disengaged from care.In addition, our results show low exposure to the intervention. Indeed, the probability of PLHIV being re-referred was sub-optimal, as they were unreachable by phone or not at home. Fieldworkers experienced logistical challenges with phone calls, such as the frequency of power cuts in households (meaning that phones were not charged), poor network coverage, and high phone numbers turnover. In addition, people were not always available at the time of the phone calls or home visits: our results showed that people were less likely to answer their phone during the earlier hours of the day, probably because they were busy with domestic duties. A linkage-to-care intervention that relies on telephone contact requires high cell phone penetration and a list of phone numbers as complete as possible and regularly updated. A strategy that addresses the challenges highlighted here could lead to better early linkage-to-care, which is critical in preventing HIV transmission and disease progression.Our study has some methodological limitations. First, it is an observational study: although the data are drawn from a cluster-randomised trial, the tracking and re-referral of HIV-positive trial participants were not randomised. However, our results come from a longitudinal study, with re-referral considered as a time-dependent variable: this allows us to measure the effects of the intervention updated for each participant over time. Secondly, we do not know whether HIV-positive trial participants were linked to care outside of the TasP trial or the DoH HIV program, which could have led to underestimating the proportion of linkage to HIV care. Thirdly, even if the TasP trial targeted a whole community, more than 70% of the included population in this analysis were women as they were more likely to be contacted and tested for HIV at home than men (who could be more likely to work or have other occupation during the day). Fourth, although standardized procedures for this linkage-to-care intervention were available to all the linkage-to-care team, we did not observe the fieldworkers in the field and we thus have no data regarding the quality of delivery of this linkage-to-care intervention, including the exact content of the phone calls and home visits, and the counselling given by the fieldworkers.Despite these limitations, while the use of phones has mainly been dedicated to tracking people already in care and on treatment [