Person: Freedberg, Kenneth
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Freedberg
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Freedberg, Kenneth
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Publication Point-of-Care CD4 Testing to Inform Selection of Antiretroviral Medications in South African Antenatal Clinics: A Cost-Effectiveness Analysis(Public Library of Science, 2015) Ciaranello, Andrea; Myer, Landon; Kelly, Kathleen; Christensen, Sarah; Daskilewicz, Kristen; Doherty, Katie; Bekker, Linda-Gail; Hou, Taige; Wood, Robin; Francke, Jordan A.; Wools-Kaloustian, Kara; Freedberg, Kenneth; Walensky, RochelleBackground: Many prevention of mother-to-child HIV transmission (PMTCT) programs currently prioritize antiretroviral therapy (ART) for women with advanced HIV. Point-of-care (POC) CD4 assays may expedite the selection of three-drug ART instead of zidovudine, but are costlier than traditional laboratory assays. Methods: We used validated models of HIV infection to simulate pregnant, HIV-infected women (mean age 26 years, gestational age 26 weeks) in a general antenatal clinic in South Africa, and their infants. We examined two strategies for CD4 testing after HIV diagnosis: laboratory (test rate: 96%, result-return rate: 87%, cost: $14) and POC (test rate: 99%, result-return rate: 95%, cost: $26). We modeled South African PMTCT guidelines during the study period (WHO “Option A”): antenatal zidovudine (CD4 ≤350/μL) or ART (CD4>350/μL). Outcomes included MTCT risk at weaning (age 6 months), maternal and pediatric life expectancy (LE), maternal and pediatric lifetime healthcare costs (2013 USD), and cost-effectiveness ($/life-year saved). Results: In the base case, laboratory led to projected MTCT risks of 5.7%, undiscounted pediatric LE of 53.2 years, and undiscounted PMTCT plus pediatric lifetime costs of $1,070/infant. POC led to lower modeled MTCT risk (5.3%), greater pediatric LE (53.4 years) and lower PMTCT plus pediatric lifetime costs ($1,040/infant). Maternal outcomes following laboratory were similar to POC (LE: 21.2 years; lifetime costs: $23,860/person). Compared to laboratory, POC improved clinical outcomes and reduced healthcare costs. Conclusions: In antenatal clinics implementing Option A, the higher initial cost of a one-time POC CD4 assay will be offset by cost-savings from prevention of pediatric HIV infection.Publication The Linkage Outcomes of a Large-scale, Rapid Transfer of HIV-infected Patients From Hospital-based to Community-based Clinics in South Africa(Oxford University Press, 2014) Cloete, Christie; Regan, Susan; Giddy, Janet; Govender, Tessa; Erlwanger, Alison; Gaynes, Melanie R.; Freedberg, Kenneth; Katz, Jeffrey; Walensky, Rochelle; Losina, Elena; Bassett, IngridBackground: President's Emergency Plan for AIDS Relief (PEPFAR) funding changes have resulted in human immunodeficiency virus (HIV) clinic closures. We evaluated linkage to care following a large-scale patient transfer from a PEPFAR-funded, hospital-based HIV clinic to government-funded, community-based clinics in Durban. Methods: All adults were transferred between March and June 2012. Subjects were surveyed 5–10 months post-transfer to assess self-reported linkage to the target clinic. We validated self-reports by auditing records at 8 clinics. Overall success of transfer was estimated using linkage to care data for both reached and unreached subjects, adjusted for validation results. Results: Of the 3913 transferred patients, 756 (19%) were assigned to validation clinics; 659 (87%) of those patients were reached. Among those reached, 468 (71%) had a validated clinic record visit. Of the 46 who self-reported attending a different validation clinic than originally assigned, 39 (85%) had a validated visit. Of the 97 patients not reached, 59 (61%) had a validated visit at their assigned clinic. Based on the validation rates for reached and unreached patients, the estimated success of transfer for the cohort overall was 82%. Conclusions: Most patients reported successful transfer to a community-based clinic, though a quarter attended a different clinic than assigned. Validation of attendance highlights that nearly 20% of patients may not have linked to care and may have experienced a treatment interruption. Optimizing transfers of HIV care to community sites requires collaboration with receiving clinics to ensure successful linkage to care.Publication Improving on effective antiretroviral therapy: how good will a cure have to be?(BMJ Publishing Group, 2017) Freedberg, Kenneth; Sax, PaulPublication Optimal breastfeeding durations for HIV‐exposed infants: the impact of maternal ART use, infant mortality and replacement feeding risk(John Wiley and Sons Inc., 2018) Mallampati, Divya; MacLean, Rachel L; Shapiro, Roger; Dabis, Francois; Engelsmann, Barbara; Freedberg, Kenneth; Leroy, Valeriane; Lockman, Shahin; Walensky, Rochelle; Rollins, Nigel; Ciaranello, AndreaAbstract Introduction: In 2010, the WHO recommended women living with HIV breastfeed for 12 months while taking antiretroviral therapy (ART) to balance breastfeeding benefits against HIV transmission risks. To inform the 2016 WHO guidelines, we updated prior research on the impact of breastfeeding duration on HIV‐free infant survival (HFS) by incorporating maternal ART duration, infant/child mortality and mother‐to‐child transmission data. Methods: Using the Cost‐Effectiveness of Preventing AIDS Complications (CEPAC)‐Infant model, we simulated the impact of breastfeeding duration on 24‐month HFS among HIV‐exposed, uninfected infants. We defined “optimal” breastfeeding durations as those maximizing 24‐month HFS. We varied maternal ART duration, mortality rates among breastfed infants/children, and relative risk of mortality associated with replacement feeding (“RRRF”), modelled as a multiplier on all‐cause mortality for replacement‐fed infants/children (range: 1 [no additional risk] to 6). The base‐case simulated RRRF = 3, median infant mortality, and 24‐month maternal ART duration. Results: In the base‐case, HFS ranged from 83.1% (no breastfeeding) to 90.2% (12‐months breastfeeding). Optimal breastfeeding durations increased with higher RRRF values and longer maternal ART durations, but did not change substantially with variation in infant mortality rates. Optimal breastfeeding durations often exceeded the previous WHO recommendation of 12 months. Conclusions: In settings with high RRRF and long maternal ART durations, HFS is maximized when mothers breastfeed longer than the previously‐recommended 12 months. In settings with low RRRF or short maternal ART durations, shorter breastfeeding durations optimize HFS. If mothers are supported to use ART for longer periods of time, it is possible to reduce transmission risks and gain the benefits of longer breastfeeding durations.Publication The cost‐effectiveness of HIV pre‐exposure prophylaxis in men who have sex with men and transgender women at high risk of HIV infection in Brazil(John Wiley and Sons Inc., 2018) Luz, Paula M; Osher, Benjamin; Grinsztejn, Beatriz; Maclean, Rachel L; Losina, Elena; Stern, Madeline E; Struchiner, Claudio J; Parker, Robert; Freedberg, Kenneth; Mesquita, Fabio; Walensky, Rochelle; Veloso, Valdilea G; Paltiel, A DavidAbstract Introduction: Men who have sex with men (MSM) and transgender women (TGW) in Brazil experience high rates of HIV infection. We examined the clinical and economic outcomes of implementing a pre‐exposure prophylaxis (PrEP) programme in these populations. Methods: We used the Cost‐Effectiveness of Preventing AIDS Complications (CEPAC)‐International model of HIV prevention and treatment to evaluate two strategies: the current standard of care (SOC) in Brazil, including universal ART access (No PrEP strategy); and the current SOC plus daily tenofovir/emtracitabine PrEP (PrEP strategy) until age 50. Mean age (31 years, SD 8.4 years), age‐stratified annual HIV incidence (age ≤ 40 years: 4.3/100 PY; age > 40 years: 1.0/100 PY), PrEP effectiveness (43% HIV incidence reduction) and PrEP drug costs ($23/month) were from Brazil‐based sources. The analysis focused on direct medical costs of HIV care. We measured the comparative value of PrEP in 2015 United States dollars (USD) per year of life saved (YLS). Willingness‐to‐pay threshold was based on Brazil's annual per capita gross domestic product (GDP; 2015: $8540 USD). Results: Lifetime HIV infection risk among high‐risk MSM and TGW was 50.5% with No PrEP and decreased to 40.1% with PrEP. PrEP increased per‐person undiscounted (discounted) life expectancy from 36.8 (20.7) years to 41.0 (22.4) years and lifetime discounted HIV‐related medical costs from $4100 to $8420, which led to an incremental cost‐effectiveness ratio (ICER) of $2530/YLS. PrEP remained cost‐effective (<1x GDP) under plausible variation in key parameters, including PrEP effectiveness and cost, initial cohort age and HIV testing frequency on/off PrEP. Conclusion: Daily tenofovir/emtracitabine PrEP among MSM and TGW at high risk of HIV infection in Brazil would increase life expectancy and be highly cost‐effective.Publication The cost‐effectiveness and budgetary impact of a dolutegravir‐based regimen as first‐line treatment of HIV infection in India(John Wiley and Sons Inc., 2018) Zheng, Amy; Kumarasamy, Nagalingeswaran; Huang, Mingshu; Paltiel, A David; Mayer, Kenneth; Rewari, Bharat B; Walensky, Rochelle; Freedberg, KennethAbstract Introduction: Dolutegravir (DTG)‐based antiretroviral therapy (ART) is recommended for first‐line HIV treatment in the US and Europe. Efavirenz (EFV)‐based regimens remain the standard of care (SOC) in India. We examined the clinical and economic impact of DTG‐based first‐line ART in the setting of India's recent guidelines change to treating all patients with HIV infection regardless of CD4 count. Methods: We used a microsimulation of HIV disease, the Cost‐Effectiveness of Preventing AIDS Complications (CEPAC)‐International model, to project outcomes in ART‐naive patients under two strategies: (1) SOC: EFV/tenofovir disoproxil fumarate (TDF)/lamivudine (3TC); and (2) DTG: DTG + TDF/3TC. Regimen‐specific inputs, including virologic suppression at 48 weeks (SOC: 82% vs. DTG: 90%) and annual costs ($98 vs. $102), were informed by clinical trial data and other sources and varied widely in sensitivity analysis. We compared incremental cost‐effectiveness ratios (ICERs), measured in $/year of life saved (YLS), to India's per capita gross domestic product ($1600 in 2015). We compared the budget impact and HIV transmission effects of the two strategies for the estimated 444,000 and 916,000 patients likely to initiate ART in India over the next 2 and 5 years. Results: Compared to SOC,DTG improved 5‐year survival from 76.7% to 83.0%, increased life expectancy from 22.0 to 24.8 years (14.0 to 15.5 years, discounted), averted 13,000 transmitted HIV infections over 5 years, increased discounted lifetime care costs from $3040 to $3240, and resulted in a lifetime ICER of $130/YLS, less than 10% of India's per capita GDP in 2015. DTG maintained an ICER below 50% of India's per capita GDP as long as the annual three‐drug regimen cost was ≤$180/year. Over a 2‐ or 5‐year horizon, total undiscounted outlays for HIV‐related care were virtually the same for both strategies. Conclusions: A generic DTG‐based regimen is likely to be cost‐effective and should be recommended for initial therapy of HIV infection in India.Publication Clinical Benefits and Cost-Effectiveness of Laboratory Monitoring Strategies to Guide Antiretroviral Treatment Switching in India(Mary Ann Liebert, Inc., 2018) Freedberg, Kenneth; Kumarasamy, Nagalingeswaran; Borre, Ethan D.; Ross, Eric L.; Mayer, Kenneth; Losina, Elena; Swaminathan, Soumya; Flanigan, Timothy P.; Walensky, RochelleAbstract Current Indian guidelines recommend twice-annual CD4 testing to monitor first-line antiretroviral therapy (ART), with a plasma HIV RNA test to confirm failure if CD4 declines, which would prompt a switch to second-line ART. We used a mathematical model to assess the clinical benefits and cost-effectiveness of alternative laboratory monitoring strategies in India. We simulated a cohort of HIV-infected patients initiating first-line ART and compared 11 strategies with combinations of CD4 and HIV RNA testing at varying frequencies. We included adaptive strategies that reduce the frequency of tests after 1 year from 6 to 12 months for virologically suppressed patients. We projected life expectancy, time on failed first-line ART, cumulative 10-year HIV transmissions, lifetime cost (2014 US dollars), and incremental cost-effectiveness ratios (ICERs). We defined strategies as cost-effective if their ICER was <1 × the Indian per capita gross domestic product (GDP, $1,600). We found that the current Indian guidelines resulted in a per person life expectancy (from mean age 37) of 150.2 months and a per person cost of $2,680. Adding annual HIV RNA testing increased survival by ∼8 months; adaptive strategies were less expensive than similar nonadaptive strategies with similar life expectancy. The most effective strategy with an ICER <1 × GDP was the adaptive HIV RNA strategy (ICER $840/year). Cumulative 10-year transmissions decreased from 27.2/1,000 person-years with standard-of-care to 20.9/1,000 person-years with adaptive HIV RNA testing. In India, routine HIV RNA monitoring of patients on first-line ART would increase life expectancy, decrease transmissions, be cost-effective, and should be implemented.Publication Development, Calibration and Performance of an HIV Transmission Model Incorporating Natural History and Behavioral Patterns: Application in South Africa(Public Library of Science, 2014) McCormick, Alethea; Abuelezam, Nadia; Rhode, Erin R.; Hou, Taige; Walensky, Rochelle; Pei, Pamela P.; Becker, Jessica E.; DiLorenzo, Madeline A.; Losina, Elena; Freedberg, Kenneth; Lipsitch, Marc; Seage, GeorgeUnderstanding HIV transmission dynamics is critical to estimating the potential population-wide impact of HIV prevention and treatment interventions. We developed an individual-based simulation model of the heterosexual HIV epidemic in South Africa and linked it to the previously published Cost-Effectiveness of Preventing AIDS Complications (CEPAC) International Model, which simulates the natural history and treatment of HIV. In this new model, the CEPAC Dynamic Model (CDM), the probability of HIV transmission per sexual encounter between short-term, long-term and commercial sex worker partners depends upon the HIV RNA and disease stage of the infected partner, condom use, and the circumcision status of the uninfected male partner. We included behavioral, demographic and biological values in the CDM and calibrated to HIV prevalence in South Africa pre-antiretroviral therapy. Using a multi-step fitting procedure based on Bayesian melding methodology, we performed 264,225 simulations of the HIV epidemic in South Africa and identified 3,750 parameter sets that created an epidemic and had behavioral characteristics representative of a South African population pre-ART. Of these parameter sets, 564 contributed 90% of the likelihood weight to the fit, and closely reproduced the UNAIDS HIV prevalence curve in South Africa from 1990–2002. The calibration was sensitive to changes in the rate of formation of short-duration partnerships and to the partnership acquisition rate among high-risk individuals, both of which impacted concurrency. Runs that closely fit to historical HIV prevalence reflect diverse ranges for individual parameter values and predict a wide range of possible steady-state prevalence in the absence of interventions, illustrating the value of the calibration procedure and utility of the model for evaluating interventions. This model, which includes detailed behavioral patterns and HIV natural history, closely fits HIV prevalence estimates.Publication A randomized trial to optimize HIV/TB care in South Africa: design of the Sizanani trial(BioMed Central, 2013) Bassett, Ingrid; Giddy, Janet; Chaisson, Christine E; Ross, Douglas; Bogart, Laura M.; Coleman, Sharon M; Govender, Tessa; Robine, Marion; Erlwanger, Alison; Freedberg, Kenneth; Katz, Jeffrey; Walensky, Rochelle; Losina, ElenaBackground: Despite increases in HIV testing, only a fraction of people newly diagnosed with HIV infection enter the care system and initiate antiretroviral therapy (ART) in South Africa. We report on the design and initial enrollment of a randomized trial of a health system navigator intervention to improve linkage to HIV care and TB treatment completion in Durban, South Africa. Methods/Design We employed a multi-site randomized controlled trial design. Patients at 4 outpatient sites were enrolled prior to HIV testing. For all HIV-infected participants, routine TB screening with sputum for mycobacterial smear and culture were collected. HIV-infected participants were randomized to receive the health system navigator intervention or usual care. Participants in the navigator arm underwent a baseline interview using a strengths-based case management approach to assist in identifying barriers to entering care and devising solutions to best cope with perceived barriers. Over 4 months, participants in the navigator arm received scheduled phone and text messages. The primary outcome of the study is linkage and retention in care, assessed 9 months after enrollment. For ART-eligible participants without TB, the primary outcome is 3 months on ART as documented in the medical record; participants co-infected with TB are also eligible to meet the primary outcome of completion of 6 months of TB treatment, as documented by the TB clinic. Secondary outcomes include mortality, receipt of CD4 count and TB test results, and repeat CD4 counts for those not ART-eligible at baseline. We hypothesize that a health system navigator can help identify and positively affect modifiable patient factors, including self-efficacy and social support, that in turn can improve linkage to and retention in HIV and TB care. Discussion We are currently evaluating the clinical impact of a novel health system navigator intervention to promote entry to and retention in HIV and TB care for people newly diagnosed with HIV. The details of this study protocol will inform clinicians, investigators, and policy makers of strategies to best support HIV-infected patients in resource-limited settings. Trial registration Clinicaltrials.gov. unique identifier: NCT01188941.Publication Validation and Calibration of a Computer Simulation Model of Pediatric HIV Infection(Public Library of Science, 2013) Ciaranello, Andrea; Morris, Bethany L.; Walensky, Rochelle; Weinstein, Milton; Ayaya, Samuel; Doherty, Kathleen; Leroy, Valeriane; Hou, Taige; Desmonde, Sophie; Lu, Zhigang; Noubary, Farzad; Patel, Kunjal; Ramirez-Avila, Lynn; Losina, Elena; Seage III, George R.; Freedberg, KennethBackground: Computer simulation models can project long-term patient outcomes and inform health policy. We internally validated and then calibrated a model of HIV disease in children before initiation of antiretroviral therapy to provide a framework against which to compare the impact of pediatric HIV treatment strategies. Methods: We developed a patient-level (Monte Carlo) model of HIV progression among untreated children <5 years of age, using the Cost-Effectiveness of Preventing AIDS Complications model framework: the CEPAC-Pediatric model. We populated the model with data on opportunistic infection and mortality risks from the International Epidemiologic Database to Evaluate AIDS (IeDEA), with mean CD4% at birth (42%) and mean CD4% decline (1.4%/month) from the Women and Infants’ Transmission Study (WITS). We internally validated the model by varying WITS-derived CD4% data, comparing the corresponding model-generated survival curves to empirical survival curves from IeDEA, and identifying best-fitting parameter sets as those with a root-mean square error (RMSE) <0.01. We then calibrated the model to other African settings by systematically varying immunologic and HIV mortality-related input parameters. Model-generated survival curves for children aged 0-60 months were compared, again using RMSE, to UNAIDS data from >1,300 untreated, HIV-infected African children. Results: In internal validation analyses, model-generated survival curves fit IeDEA data well; modeled and observed survival at 16 months of age were 91.2% and 91.1%, respectively. RMSE varied widely with variations in CD4% parameters; the best fitting parameter set (RMSE = 0.00423) resulted when CD4% was 45% at birth and declined by 6%/month (ages 0-3 months) and 0.3%/month (ages >3 months). In calibration analyses, increases in IeDEA-derived mortality risks were necessary to fit UNAIDS survival data. Conclusions: The CEPAC-Pediatric model performed well in internal validation analyses. Increases in modeled mortality risks required to match UNAIDS data highlight the importance of pre-enrollment mortality in many pediatric cohort studies.