Tracing of patients lost to follow-up and HIV transmission: mathematical modeling study based on 2 large ART programs in Malawi

Centering healthcare workers in digital health design: Usability and acceptability of two-way texting to improve retention in antiretroviral therapy in a public HIV clinic in Lilongwe, Malawi

New initiates on antiretroviral therapy (ART) are at high risk of treatment discontinuation, putting their health at risk. In low- and middle-income countries, like Malawi, appropriate digital health applications (apps) must fit into local clinic, connectivity and resource constraints. We describe the human centered design (HCD) and development process of an open-source, hybrid, two-way texting (2wT) system to improve ART retention. We detail the critical role of diverse healthcare workers (HCWs) in the HCD process to inform app usability, create buy-in, and ensure appropriate optimization for the local context. We optimized 2wT usability and acceptability over three HCD phases: 1) informal feedback sessions with diverse 2wT stakeholders, 2) a small pilot, and 3) key informant interviews. Phase one included four sessions with diverse HCWs, including "expert ART clients", clinical, technical, supervisory, and evaluation teams to inform 2wT design. In phase 2, a small pilot with 50 participating ART clients aimed to inform implementation improvement. Phase three included interviews with ten HCWs to deepen understanding of 2wT acceptability and usability, documenting strengths and weaknesses to inform optimization. Multi-phase feedback sessions with HCWs helped refine 2wT language and message timing for both weekly and tailored client-specific visit reminders. The pilot led to improvements in educational materials to guide client responses and ease interaction with HCWs. In interviews, the HCWs appreciated the HCD co-creation process, suggested ways to increase access for low-literacy clients or those without consistent phone access, and felt integrating 2wT with other eHealth platforms would improve scalability. Inclusion of HCWs across phases of HCD design, adaption, and optimization increased 2wT usability and acceptability among HCWs in this setting. Engaging HCWs into 2wT co-ownership from inception appears successful in co-creation of an app that will meet HCW needs, and therefore, enhance support for 2wT clients to attend visits and remain in care.

The spatial spread of HIV in Malawi: An individual-based mathematical model

Background

The prevalence of HIV varies greatly between and within countries. We aimed to build a comprehensive mathematical modelling tool capable of exploring the reasons of this heterogeneity and test its applicability by simulating the Malawian HIV epidemic.

Methods

We developed a flexible individual-based mathematical model for HIV transmission that comprises a spatial representation and individual-level determinants. We tested this model by calibrating it to the HIV epidemic in Malawi and exploring whether the heterogeneity in HIV prevalence could be reproduced. We ran the model for 1975-2030 with five alternative realizations of the geographical structure and mobility: (I) no geographical structure; 28 administrative districts including (II) only permanent inter-district relocations, (III) inter-district permanent relocations and casual sexual relationships, or (IV) permanent relocations between districts and to/from abroad and inter-district casual sex; and (V) a grid of 10 × 10km2 cells, with permanent relocations and between-cell casual relationships. We assumed HIV was present in 1975 in the districts with >10 % prevalence in 2010. We calibrated the models to national and district-level prevalence estimates.

Results

Reaching the national prevalence required all adults to have at least 22 casual sex acts/year until 1990. Models II, III and V reproduced the geographical heterogeneity in prevalence in 2010 to some extent if between-district relationships were excluded (Model II; 4.9 %-21.1 %). Long-distance casual partnership mixing mitigated the differences in prevalence substantially (range across districts 4.1%-18.9 % in 2010 in Model III; 4.0%-17.6 % in Model V); with international migration the differences disappeared (Model IV; range across districts 6.9%-13.3 % in 2010). National prevalence decreased to 5 % by 2030.

Conclusion

Earlier introduction of HIV into the Southern part of Malawi may cause some level of heterogeneity in HIV prevalence. Other factors such as sociobehavioural characteristics are likely to have a major impact and need investigation.

Adherence to antiretroviral therapy and associated factors among human immunodeficiency -positive patients accessing treatment at health centers in East Gojjam Zone, Northwest Ethiopia, 2019: Community-based cross-sectional study

Background

To achieve an effective treatment outcome, Antiretroviral Therapy (ART) for people living with the Human immunodeficiency virus (HIV) needs at least a 95% adherence level. The aim was to assess adherence to antiretroviral therapy and its associated factors among patients accessing treatment at Health centers in East Gojjam Zone, Northwest Ethiopia.

Methods

A community-based cross-sectional study was conducted on 770 HIV-positive patients from April 1 to May 10, 2019, in East Gojjam Zone. The study participants were selected by simple random computerized sampling methods. Primary data was collected from the patients through face-to-face interviews and home-to-home visits. Bivariable and multivariable binary logistic regression analyses were done. Independent variables with a P-value of <0.2 in bivariable binary logistic regression analysis were considered for multivariable binary logistic regression analysis. A P-value of <0.05 was used as the cut-off point for the presence of statistical significance.

Results

About 396 (51.8%) of the study participants had good adherence. Being 18-24 years old [Adjusted Odd Ratio (AOR) = 0.43; 95% CI = 0.21-0.86], having a marital status of being widowed (AOR = 0.29; 95% CI = 0.14-0.58), having a disease duration of >10 years (AOR = 0.47; 95% CI = 0.24-0.94), taking a drug regimen of Tenofovir (TDF) + Lamivudine (3 TC) + Nevirapine (NVP) (AOR = 2.94; 95% CI = 1.406.15), not being socially stigmatized (AOR = 0.52; 95% CI = 0.34-0.78), and having not encountered an opportunistic infection (AOR = 3.91; 95% CI = 2.68-5.72) were significant factors.

Conclusions

The level of adherence was low. Opportunistic infection prevention, reduction of social stigma, and other intervention activities should be strengthened to increase the level of adherence.

Centering healthcare workers in developing digital health interventions: usability and acceptability of a two-way texting retention intervention in a public HIV clinic in Lilongwe, Malawi

Background

New initiates on antiretroviral therapy (ART) are at high risk of treatment discontinuation, putting their health at risk. In low-resource settings, like Malawi, appropriate digital health applications must fit into local connectivity and resource constraints. Target users' perspectives are critical for app usability, buy-in and optimization. We describe the formative stages of the design of a two-way text-based (2wT) system of tailored reminders and adherence messages for new ART initiates and share results from key informant interviews with HCWs focused on app usability and acceptability.

Methods

Using a co-creation approach with clients, clinical, technical and evaluation teams and over app development, we held four informal user feedback sessions, a small pilot with 50 clients, and ten key informant (KIIs) to deepen our understanding of healthcare workers (HCWs) needs, acceptability and usability.

Results

Formative research informed the design of interactive client-to-HCW communication, refining of the language and timing of weekly text blast motivational messages and tailored client-specific visit reminders. Informal feedback from HCW stakeholders also informed educational materials to enhance 2wT client understanding of how to report transfers, request visit date changes and ask questions related to their visits. In KII, HCWs noted their appreciation for the co-creation process, believing that the participatory HCD process and responsive design team enabled the development of a highly acceptable and usable 2wT digital tool. HCWs also suggested future improvements to promote inclusion of clients of varying literacy levels and economic backgrounds as well as integrating with other health platforms to improve uptake of 2wT.

Conclusions

Inclusion of HCWs increased perceptions of app usability and acceptability among HCWs. HCWs believe that 2wT will improve on-time ART visit attendance and provide valuable early retention in care support. The co-creation approach appears successful in designing an app that will meet HCW needs and, therefore, support client adherence to visits.

Time Until Loss to Follow-Up, Incidence, and Predictors Among Adults Taking ART at Public Hospitals in Southern Ethiopia

Introduction

According to the World Health Organization, more than seventeen million people were accessing ART in 2015 globally. Adherence to effective ART reduced the risk of transmitting the virus to uninfected persons. The government and other stakeholders’ focus was high to reduce the rate of loss to follow-up in HIV programs among patients who are already on ART follow-up, but its incidence rate increases from time to time.

Methods

A retrospective cohort study was conducted among the records enrolled from 1 January 2013 to 30 December 2017 at Public hospitals in Southern Ethiopia. Data were entered into Epi info V 7 and exported to STATA V 14 for analysis. The Kaplan–Meier survival curve together with a log rank test was used to estimate the survival time of the ART attending patients. Variables which had p-value <0.05 in multivariable analysis using the cox proportional hazard model were declared as statistically significant.

Results

The incidence rate of loss to follow-up from ART services among adults attending ART was 6.48 (95% CI:5.67,7.29) per 1000 person months. The cumulative survival probability at the end of the 10th, 20th, 40th and 60th follow-up month was 0.89 (95% CI:0.87,0.91), 0.82 (95% CI:0.79,0.85), 0.78 (95% CI:0.75,0.81) and 0.74 (95% CI:0.70,0.77), respectively. Distance >5 kilometers (AHR:3.71; 95% CI:2.32,5.95), not having registered phone number (AHR:2.52; 95% CI:1.76,3.60), not initiating Isoniazid (AHR:2.15; 95% CI:1.50,3.08), body mass index <18.50kg/m² (AHR:1.87; 95% CI: 1.18; 2.97) and not having primary caregiver (AHR: 2.59; 95% CI: 1.84, 3.66) were statistically significant predictors of loss to follow-up.

Conclusion

The time until loss to follow-up was high in the first 20 months of the initiation of the ART and it declines after 20 months; longer distance between home and hospital, not having registered phone number, not initiating INH, lower body mass index and not having primary caregiver were the independent predictors of loss to follow-up from ART services.

The role of HIV viral load in mathematical models of HIV transmission and treatment: a review

Introduction

HIV viral load (VL) is accepted as a key biomarker in HIV transmission and pathogenesis. This paper presents a review of the role of VL testing in mathematical models for HIV prevention and treatment.

Methods

A search for simulation models of HIV was conducted in PubMed, yielding a total of 1210 studies. Publications before the year 2000, studies involving animals and analyses that did not use mathematical simulations were excluded. The full text of eligible articles was sourced and information about the intervention and population being modelled, type of modelling approach and disease monitoring strategy was extracted.

Results and discussion

A total of 279 studies related to HIV simulation models were included in the review, though only 17 (6%) included consideration of VL or VL testing and were evaluated in detail. Within the studies that included assessment of VL, routine monitoring was the focus, and usually in comparison to alternate monitoring strategies such as clinical or CD4 count-based monitoring. The majority of remaining models focus on the impact or delivery of antiretroviral therapy (n=68; 27%), pre-exposure prophylaxis (n=28; 11%) and/or HIV testing (n=24; 9%) on population estimates of HIV epidemiology and exclude consideration of VL. Few studies investigate or compare alternate VL monitoring frequencies, and only a small number of studies overall (3%) include consideration of vulnerable population groups such as pregnant women or infants.

Conclusions

There are very few simulations of HIV treatment or prevention that include VL measures, despite VL being recognised as the key determinant of both transmission and treatment outcomes. With growing emphasis on VL monitoring as key tool for population-level HIV control, there is a clear need for simulations of HIV epidemiology based on VL.

Economic and public health impact of decentralized HIV viral load testing: A modelling study in Kenya

Kenya has the world’s 4^th largest HIV burden. Various strategies to control the epidemic have been implemented, including the implementation of viral load (VL) testing to monitor HIV patients on ARVs. Like many resource limited settings, Kenya’s healthcare system faces serious challenges in effectively providing quality health services to its population. Increased investments to strengthen the country’s capacity to diagnose, monitor and treat diseases, particularly HIV and TB, continue to be made but are still inadequate in the face of global health goals like the UNAIDS 90:90:90 which require scaling up of VL tests amid existing constraints. In Kenya, there is an increase in the demand for VL tests amidst these existing constraints. The GeneXpert system is a diagnostic point-of-care technology that can quantify, amongst others, HIV VL. Currently, GeneXpert technology is widely distributed in Kenya for testing of tuberculosis. This study aimed to determine the economic and public health impact of incorporating VL test modules on the existing GeneXpert infrastructure. Markov models were constructed for different populations (non-pregnant adults, pregnant women and children). The scenarios analysed were 100% centralized VL testing compared to 50% GeneXpert plus 50% centralized VL testing, with time horizons of 5 years for the adult and child populations, and 31 months for the pregnant population. Incremental effectiveness was measured in terms of the number of HIV transmissions or opportunistic infections avoided when implementing the GeneXpert scenario compared to a 100% centralized scenario. The model indicated that, for all three populations combined, the GeneXpert scenario resulted in 117 less HIV transmissions and 393 less opportunistic infections. The cost decreased by $21,978,755 for the non-pregnant and pregnant adults and $22,808,533 for non-pregnant adults, pregnant adults and children. The model showed that GeneXpert would cost less and be more effective in terms of total cost per HIV transmission avoided and the total cost per opportunistic infection avoided, except for the pregnant population, when considered separately.

How to achieve the global 90-90-90 target by 2020 in sub-Saharan Africa? A mathematical modelling study

OBJECTIVES

The 90-90-90 target states that by 2020, 90% of people living with HIV should be diagnosed, 90% of those diagnosed treated, and 90% of those treated virally suppressed. We assessed the actions needed in each country of sub-Saharan Africa to achieve the 90-90-90 target.

METHODS

We developed a mathematical model to assess the number of patients needing to start antiretroviral therapy (ART) between 2017 and 2020 to achieve 81% coverage by 2020 in each country, and the proportion of treated patients who are virally suppressed in four scenarios, combining two scenarios of retention (current-level or perfect), and routine viral load monitoring (current or universal coverage). We performed two separate simulations, one using observed failure rates from cohort studies, and one with considerably lower failure rates to set a theoretical lower limit.

RESULTS

Our model projected that 2.9 million people started ART in 2017 in sub-Saharan Africa. If, depending on scenario, at least 2.2-2.7 million patients continue to start ART annually, 81% ART coverage will be reached in 2020 in sub-Saharan Africa on average. In 37% of the countries, a multiple-fold increase in annual number of patients starting ART is needed. Virological suppression >90% in 2020 could be reached only in the best-case scenario assuming low probability of treatment failure, elimination of treatment interruptions, and universal routine viral load monitoring.

CONCLUSION

The 90-90-90 target is realistic in sub-Saharan Africa on average, but not necessarily in all individual countries. Each country should identify and focus on the specific gaps needing attention.

Incidence and predictors of loss to follow up among HIV-infected adults at Pawi General Hospital, northwest Ethiopia: competing risk regression model

Objective

This study was aimed at assessing the incidence of lost-to-follow-up and its predictors among HIV-positive adults after initiation into antiretroviral therapy at Pawi General Hospital, northwest Ethiopia.

Results

The overall cumulative incidence of lost-to-follow-up after ART initiation was high, 11.6 (95% CI 9.8–13.7) per 100 adult-years follow-up time. Independent significant predictors of lost to follow up were being aged 15–28 years (aSHR = 0.44; 95% CI 0.24–0.83), being on WHO clinical stage IV (aSHR = 2.09; 95% CI 1.02–3.13); and receiving isoniazid preventive therapy (aSHR = 0.11; 95% CI 0.06–0.18).

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3407-5) contains supplementary material, which is available to authorized users.

The Effect of Monitoring Viral Load and Tracing Patients Lost to Follow-up on the Course of the HIV Epidemic in Malawi: A Mathematical Model

Background

Antiretroviral therapy (ART) reduces HIV transmission, but treated patients may again become infectious. We used a mathematical model to determine whether ART as prevention is more effective if viral load (VL) is routinely monitored and patients lost to follow-up (LTFU) traced.

Methods

We simulated ART cohorts to parameterize a deterministic transmission model calibrated to Malawi. We investigated the following strategies for improving treatment and retention: monitoring VL every 12 or 24 months, tracing patients LTFU, or a generic strategy leading to uninterrupted treatment. We tested 3 scenarios, where ART scale-up continues at current (Universal ART), reduced (Failed scale-up), or accelerated speed (Test&Treat).

Results

In the Universal ART scenario, between 2017 and 2020 (2050), monitoring VL every 24 months prevented 0.5% (0.9%), monitoring every 12 months prevented 0.8% (1.4%), tracing prevented 0.3% (0.5%), and uninterrupted treatment prevented 5.5% (9.9%) of HIV infections. Failed scale-up resulted in 25% more infections than the Universal ART scenarios, whereas Test&Treat resulted in 7%–8% less.

Conclusions

Test&Treat reduces transmission of HIV, despite individual cases of treatment failure and ART interruption. Whereas viral load monitoring and tracing have only a minor impact on transmission, interventions that aim to minimize treatment interruptions can further increase the preventive effect of ART.

Twelve-year mortality in adults initiating antiretroviral therapy in South Africa

Introduction: South Africa has the largest number of individuals living with HIV and the largest antiretroviral therapy (ART) programme worldwide. In September 2016, ART eligibility was extended to all 7.1 million HIV-positive South Africans. To ensure that further expansion of services does not compromise quality of care, long-term outcomes must be monitored. Few studies have reported long-term mortality in resource-constrained settings, where mortality ascertainment is challenging. Combining site records with data linked to the national vital registration system, sites in the International Epidemiology Databases to Evaluate AIDS Southern Africa collaboration can identify >95% of deaths in patients with civil identification numbers (IDs). This study used linked data to explore long-term mortality and viral suppression among adults starting ART in South Africa.

Methods: The study was a cohort analysis of routine data on adults with IDs starting ART 2004–2015 in five large ART cohorts. Mortality was estimated overall and by gender using the Kaplan-Meier estimator and Cox’s proportional hazards regression. Standardized mortality ratios (SMRs) were calculated by dividing observed numbers of deaths by numbers expected if patients had been HIV-negative. Viral suppression in patients with viral loads (VLs) in their last year of follow-up was the secondary outcome.

Results: Among 72,812 adults followed for 350,376 person years (pyrs), the crude mortality rate was 3.08 (95% CI 3.02–3.14)/100 pyrs. Patients were predominantly female (67%) and the percentage of men initiating ART did not increase. Cumulative mortality 12 years after ART initiation was 23.9% (33.4% male and 19.4% female). Mortality peaked in patients enrolling in 2007–2009 and was higher in men than women at all durations. Observed mortality rates were higher than HIV-negative mortality, decreasing with duration. By 48 months, observed mortality was close to that in the HIV-negative population, and SMRs were similar for all baseline CD4 strata. Three-quarters of patients had VLs in their last year, and 86% of these were virally suppressed.

Conclusions: The South African ART programme has shown a remarkable ability to initiate and manage patients successfully over 12 years, despite rapid expansion. With further scale-up, testing and initiating men on ART must be a national priority.

Who will be lost? Identifying patients at risk of loss to follow-up in Malawi. The DREAM Program Experience

OBJECTIVES

Retention of subjects in HIV treatment programmes is crucial for the success of treatment. We evaluated retention/loss to follow-up (LTFU) in subjects receiving established care in Malawi.

METHODS

Data for HIV-positive patients registered in Drug Resource Enhancement Against AIDS and Malnutrition centres in Malawi prior to 2014 were reviewed. Visits entailing HIV testing/counselling, laboratory evaluations, nutritional evaluation/supplementation, community support, peer education, and antiretroviral (ART) monitoring/pharmacy were noted. LTFU was defined as > 90 days without an encounter. Parameters potentially associated with LTFU were explored, with univariate/multivariate logistic regression analyses being performed.

RESULTS

Fifteen thousand and ninety-nine patients registered before 2014; 202 (1.3%) were lost to follow-up (LTFU) (1.3%). Nine (0.5%) of 1744 paediatric patients were LTFU vs. 1.4% (n = 193) of 13 355 adults (P < 0.001). Subjects who were LTFU had fewer days in care than retained subjects (1338 vs. 1544, respectively; P < 0.001) and a longer duration of ART (1530 vs. 1300 days, respectively; P < 0.001). Subjects who were LTFU had higher baseline HIV viral loads (P = 0.016) and higher body mass indexes (P < 0.001), were more likely to live in urban settings (88% of patients who were LTFU lived in urban settings) with better housing [relative risk (RR) 2.3; 95% confidence interval (CI) 1.67-3.09; P < 0.001], and were more likely to be educated (RR 1.88; 95% CI 1.42-2.50; P < 0.001). Distance to the centre and cost of transportation were associated with LTFU (RR 3.4; 95% CI 2.84-5.37; P < 0.001), as was absence of a maternal figure (RR 1.57; 95% CI 1.17-2.09; P < 0.001). Viral load, distance index, education and a maternal figure were predictive of LTFU.

CONCLUSIONS

Educated, urbanized HIV-infected adults living far from programme centres are at high risk of LTFU, particularly if there is no maternal figure in the household. These variables must be taken into consideration when developing retention strategies.

Prospects for HIV control in South Africa: a model-based analysis

Background

The goal of virtual elimination of horizontal and mother-to-child HIV transmission in South Africa (SA) has been proposed, but there have been few systematic investigations of which interventions are likely to be most critical to reducing HIV incidence.

Objective

This study aims to evaluate SA's potential to achieve virtual elimination targets and to identify which interventions will be most critical to achieving HIV incidence reductions.

Design

A mathematical model was developed to simulate the population-level impact of different HIV interventions in SA. Probability distributions were specified to represent uncertainty around 32 epidemiological parameters that could be influenced by interventions, and correlation coefficients (r) were calculated to assess the sensitivity of the adult HIV incidence rates and mother-to-child transmission rates (2015–2035) to each epidemiological parameter.

Results

HIV incidence in SA adults (ages 15–49) is expected to decline from 1.4% in 2011–2012 to 0.29% by 2035 (95% CI: 0.10–0.62%). The parameters most strongly correlated with future adult HIV incidence are the rate of viral suppression after initiating antiretroviral treatment (ART) (r=−0.56), the level of condom use in non-marital relationships (r=−0.40), the phase-in of intensified risk-reduction counselling for HIV-positive adults (r=0.29), the uptake of medical male circumcision (r=−0.24) and the phase-in of universal ART eligibility (r=0.22). The paediatric HIV parameters most strongly associated with mother-to-child transmission rates are the relative risk of transmission through breastfeeding when the mother is receiving ART (r=0.70) and the rate of ART initiation during pregnancy (r=−0.16).

Conclusions

The virtual elimination target of a 0.1% incidence rate in adults will be difficult to achieve. Interventions that address the infectiousness of patients after ART initiation will be particularly critical to achieving long-term HIV incidence declines in South Africa.

The need for second-line antiretroviral therapy in adults in sub-Saharan Africa up to 2030: a mathematical modelling study

BACKGROUND

The number of patients in need of second-line antiretroviral drugs is increasing in sub-Saharan Africa. We aimed to project the need of second-line antiretroviral therapy in adults in sub-Saharan Africa up to 2030.

METHODS

We developed a simulation model for HIV and applied it to each sub-Saharan African country. We used the WHO country intelligence database to estimate the number of adult patients receiving antiretroviral therapy from 2005 to 2014. We fitted the number of adult patients receiving antiretroviral therapy to observed estimates, and predicted first-line and second-line needs between 2015 and 2030. We present results for sub-Saharan Africa, and eight selected countries. We present 18 scenarios, combining the availability of viral load monitoring, speed of antiretroviral scale-up, and rates of retention and switching to second-line. HIV transmission was not included.

FINDINGS

Depending on the scenario, 8·7-25·6 million people are expected to receive antiretroviral therapy in 2020, of whom 0·5-3·0 million will be receiving second-line antiretroviral therapy. The proportion of patients on treatment receiving second-line therapy was highest (15·6%) in the scenario with perfect retention and immediate switching, no further scale-up, and universal routine viral load monitoring. In 2030, the estimated range of patients receiving antiretroviral therapy will remain constant, but the number of patients receiving second-line antiretroviral therapy will increase to 0·8-4·6 million (6·6-19·6%). The need for second-line antiretroviral therapy was two to three times higher if routine viral load monitoring was implemented throughout the region, compared with a scenario of no further viral load monitoring scale-up. For each monitoring strategy, the future proportion of patients receiving second-line antiretroviral therapy differed only minimally between countries.

INTERPRETATION

Donors and countries in sub-Saharan Africa should prepare for a substantial increase in the need for second-line drugs during the next few years as access to viral load monitoring improves. An urgent need exists to decrease the costs of second-line drugs.

FUNDING

World Health Organization, Swiss National Science Foundation, National Institutes of Health.

Characteristics of antiretroviral therapy-naïve patients lost-to-care in HIV clinics in Democratic Republic of Congo, Cameroon, and Burundi

Antiretroviral therapy (ART)-naïve patients are vulnerable to becoming lost-to-care (LTC) because they are not monitored as often as patients on treatment. We examined data from 19,461 HIV positive adults at 10 HIV clinics in Democratic Republic of Congo (DRC), Cameroon, and Burundi participating in the Phase 1 International epidemiologic Databases to Evaluate AIDS Central Africa (IeDEA-CA) study. Patients were LTC if they were ART-naïve and did not return within 7 months of the end of data collection. Logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs) for risk factors associated with LTC. Of 5353 ART-naïve patients, 4420 (83%) were LTC and 933 (17%) were in-care. The odds of being LTC were greatest among patients from DRC (OR = 2.16, CI: 1.64-2.84, p < .0001), males (OR = 1.39, CI: 1.15-1.69, p = .0009), and ages 18-49 (OR = 1.45, CI: 1.16-1.82, p = .001). The odds of being LTC were least among patients with a WHO Clinical Stage of 1 or 2 (OR = 0.65, CI: 0.55-0.77, p < .0001) and in a perceived concordant relationship (OR = 0.61, CI: 0.43-0.87, p < .0001). LTC patients were more likely to have characteristics associated with higher risk for HIV transmission and progression. Many entered care at advanced stages and were less likely to know their partner's serostatus. Greater efforts to retain ART-naïve patients may increase earlier initiation of ART.

Predictors of dropout from care among HIV-infected patients initiating antiretroviral therapy at a public sector HIV treatment clinic in sub-Saharan Africa

Background

In sub-Saharan Africa (SSA), antiretroviral therapy (ART) can prolong life for HIV-infected patients. However, patients initiating ART, especially in routine treatment programs, commonly dropout from care either due to death or loss to follow-up.

Methods

In a cohort of HIV-infected patients initiating ART at a public sector clinic in Uganda, we assessed predictors of dropout from care (a composite outcome combining death and loss to follow-up). From a large set of socio-demographic, clinical, and laboratory variables routinely collected at ART initiation, we selected those predicting dropout at P <0.1 in unadjusted analyses for inclusion into a multivariable proportional hazards regression model. We then used a stepwise backward selection procedure to identify variables which independently predicted dropout at P <0.05.

Results

Data from 5,057 patients were analyzed. The median age was 33 years (IQR 28 to 40) and 27.4 % had CD4+ T-cell counts <100 cells/μL at ART initiation. The median duration of follow-up was 24 months (IQR = 14 to 42, maximum follow-up = 64 months). Overall dropout was 26.9 % (established cumulative mortality = 2.3 %, loss to follow-up = 24.6 %), 5.6 % were transferred to other service providers, and 67.5 % were retained in care. A diagnosis of Kaposi’s sarcoma (hazard ratio (HR) = 3.3, 95 % CI 2.5 to 4.5); HIV-associated dementia (HR = 2.6, 95 % CI 1.5 to 4.6); history of cryptococcosis (HR = 2.2, 95 % CI 1.4 to 3.3); and reduced hemoglobin concentration (<11 g/dl versus ≥13.8 g/dl (HR = 1.9, 95 % CI 1.6 to 2.2) were strong predictors of dropout. Other independent predictors of dropout were: year of ART initiation; weight loss ≥10 %; reduced total lymphocyte count; chronic diarrhea; male sex; young age (≤28 years); and marital status.

Conclusions

Among HIV-infected patients initiating ART at a public sector clinic in SSA, biological factors that usually predict death were especially predictive of dropout. As most of the dropouts were lost to follow-up, this observation suggests that many losses to follow-up may have died. Future studies are needed to identify appropriate interventions that may improve both individual-level patient outcomes and outcome ascertainment among HIV-infected ART initiators in this setting.

Impact and Cost-Effectiveness of Hypothetical Strategies to Enhance Retention in Care within HIV Treatment Programs in East Africa

OBJECTIVES

Attrition from care among HIV infected patients can lead to poor clinical outcomes. Our objective was to evaluate hypothetical interventions seeking to improve retention-in-care (RIC) for HIV-infected patients in East Africa, asking whether they could offer favorable value compared to earlier ART initiation.

METHODS

We used a micro-simulation model to analyze two RIC focused strategies within an East African HIV treatment program--"risk reduction," defined as intervention(s) that decrease the risk of attrition from care; and "outreach," defined as interventions that find patients and relink them with care. We compared this to earlier ART treatment as a measure of the potential health benefits forgone (e.g., opportunity cost).

RESULTS

Reducing attrition by 40% at an average cost of $10 per person remains a less efficient use of resources compared to ensuring full access to ART (cost- effectiveness ratio $1300 vs $3700) for ART eligible patients. An outreach intervention had limited clinical benefit in our simulation. If intervention costs are <$10 per person, however, an intervention able to achieve a 40% (or greater) reduction in attrition may be a cost-effective next implementation option following implementation of earlier ART treatment.

CONCLUSIONS

Our results suggest that programs should consider retention focused programs once they have already achieved high degrees of ART coverage among eligible patients. It is important that decision makers understand the epidemiology and associated outcomes of those patients who are classified as lost to follow up in their systems prior to implementation in order to achieve the highest value.

The cost-effectiveness of monitoring strategies for antiretroviral therapy of HIV infected patients in resource-limited settings: software tool

Background

The cost-effectiveness of routine viral load (VL) monitoring of HIV-infected patients on antiretroviral therapy (ART) depends on various factors that differ between settings and across time. Low-cost point-of-care (POC) tests for VL are in development and may make routine VL monitoring affordable in resource-limited settings. We developed a software tool to study the cost-effectiveness of switching to second-line ART with different monitoring strategies, and focused on POC-VL monitoring.

Methods

We used a mathematical model to simulate cohorts of patients from start of ART until death. We modeled 13 strategies (no 2^nd-line, clinical, CD4 (with or without targeted VL), POC-VL, and laboratory-based VL monitoring, with different frequencies). We included a scenario with identical failure rates across strategies, and one in which routine VL monitoring reduces the risk of failure. We compared lifetime costs and averted disability-adjusted life-years (DALYs). We calculated incremental cost-effectiveness ratios (ICER). We developed an Excel tool to update the results of the model for varying unit costs and cohort characteristics, and conducted several sensitivity analyses varying the input costs.

Results

Introducing 2^nd-line ART had an ICER of US$1651-1766/DALY averted. Compared with clinical monitoring, the ICER of CD4 monitoring was US$1896-US$5488/DALY averted and VL monitoring US$951-US$5813/DALY averted. We found no difference between POC- and laboratory-based VL monitoring, except for the highest measurement frequency (every 6 months), where laboratory-based testing was more effective. Targeted VL monitoring was on the cost-effectiveness frontier only if the difference between 1^st- and 2^nd-line costs remained large, and if we assumed that routine VL monitoring does not prevent failure.

Conclusion

Compared with the less expensive strategies, the cost-effectiveness of routine VL monitoring essentially depends on the cost of 2^nd-line ART. Our Excel tool is useful for determining optimal monitoring strategies for specific settings, with specific sex-and age-distributions and unit costs.

gems: An R Package for Simulating from Disease Progression Models

Mathematical models of disease progression predict disease outcomes and are useful epidemiological tools for planners and evaluators of health interventions. The 𝖱 package gems is a tool that simulates disease progression in patients and predicts the effect of different interventions on patient outcome. Disease progression is represented by a series of events (e.g., diagnosis, treatment and death), displayed in a directed acyclic graph. The vertices correspond to disease states and the directed edges represent events. The package gems allows simulations based on a generalized multistate model that can be described by a directed acyclic graph with continuous transition-specific hazard functions. The user can specify an arbitrary hazard function and its parameters. The model includes parameter uncertainty, does not need to be a Markov model, and may take the history of previous events into account. Applications are not limited to the medical field and extend to other areas where multistate simulation is of interest. We provide a technical explanation of the multistate models used by gems, explain the functions of gems and their arguments, and show a sample application.

Modeling the implementation of universal coverage for HIV treatment as prevention and its impact on the HIV epidemic

The Joint United Nations Programme on HIV/AIDS (UNAIDS) recently updated its global targets for antiretroviral therapy (ART) coverage for HIV-positive persons under which 90 % of HIV-positive people are tested, 90 % of those are on ART, and 90 % of those achieve viral suppression. Treatment policy is moving toward treating all HIV-infected persons regardless of CD4 cell count-otherwise known as treatment as prevention-in order to realize the full therapeutic and preventive benefits of ART. Mathematical models have played an important role in guiding the development of these policies by projecting long-term health impacts and cost-effectiveness. To guide future policy, new mathematical models must consider the barriers patients face in receiving and taking ART. Here, we describe the HIV care cascade and ART delivery supply chain to examine how mathematical modeling can provide insight into cost-effective strategies for scaling-up ART coverage in sub-Saharan Africa and help achieve universal ART coverage.