Simulations for designing and interpreting intervention trials in infectious diseases.

BACKGROUND: Interventions in infectious diseases can have both direct effects on individuals who receive the intervention as well as indirect effects in the population. In addition, intervention combinations can have complex interactions at the population level, which are often difficult to adequately assess with standard study designs and analytical methods. DISCUSSION: Herein, we urge the adoption of a new paradigm for the design and interpretation of intervention trials in infectious diseases, particularly with regard to emerging infectious diseases, one that more accurately reflects the dynamics of the transmission process. In an increasingly complex world, simulations can explicitly represent transmission dynamics, which are critical for proper trial design and interpretation. Certain ethical aspects of a trial can also be quantified using simulations. Further, after a trial has been conducted, simulations can be used to explore the possible explanations for the observed effects. CONCLUSION: Much is to be gained through a multidisciplinary approach that builds collaborations among experts in infectious disease dynamics, epidemiology, statistical science, economics, simulation methods, and the conduct of clinical trials.

Effect of a cash transfer programme for schooling on prevalence of HIV and herpes simplex type 2 in Malawi: a cluster randomised trial.

BACKGROUND: Lack of education and an economic dependence on men are often suggested as important risk factors for HIV infection in women. We assessed the efficacy of a cash transfer programme to reduce the risk of sexually transmitted infections in young women. METHODS: In this cluster randomised trial, never-married women aged 13-22 years were recruited from 176 enumeration areas in the Zomba district of Malawi and randomly assigned with computer-generated random numbers by enumeration area (1:1) to receive cash payments (intervention group) or nothing (control group). Intervention enumeration areas were further randomly assigned with computer-generated random numbers to conditional (school attendance required to receive payment) and unconditional (no requirements to receive payment) groups. Participants in both intervention groups were randomly assigned by a lottery to receive monthly payments ranging from US$1 to $5, while their parents were independently assigned with computer-generated random numbers to receive $4-10. Behavioural risk assessments were done at baseline and 12 months; serology was tested at 18 months. Participants were not masked to treatment status but counsellors doing the serologic testing were. The primary outcomes were prevalence of HIV and herpes simplex virus 2 (HSV-2) at 18 months and were assessed by intention-to-treat analyses. The trial is registered, number NCT01333826. FINDINGS: 88 enumeration areas were assigned to receive the intervention and 88 as controls. For the 1289 individuals enrolled in school at baseline with complete interview and biomarker data, weighted HIV prevalence at 18 month follow-up was 1·2% (seven of 490 participants) in the combined intervention group versus 3·0% (17 of 799 participants) in the control group (adjusted odds ratio [OR] 0·36, 95% CI 0·14-0·91); weighted HSV-2 prevalence was 0·7% (five of 488 participants) versus 3·0% (27 of 796 participants; adjusted OR 0·24, 0·09-0·65). In the intervention group, we noted no difference between conditional versus unconditional intervention groups for weighted HIV prevalence (3/235 [1%] vs 4/255 [2%]) or weighted HSV-2 prevalence (4/233 [1%] vs 1/255 [<1%]). For individuals who had already dropped out of school at baseline, we detected no significant difference between intervention and control groups for weighted HIV prevalence (23/210 [10%] vs 17/207 [8%]) or weighted HSV-2 prevalence (17/211 [8%] vs 17/208 [8%]). INTERPRETATION: Cash transfer programmes can reduce HIV and HSV-2 infections in adolescent schoolgirls in low-income settings. Structural interventions that do not directly target sexual behaviour change can be important components of HIV prevention strategies. FUNDING: Global Development Network, Bill & Melinda Gates Foundation, National Bureau of Economic Research Africa Project, World Bank's Research Support Budget, and several World Bank trust funds (Gender Action Plan, Knowledge for Change Program, and Spanish Impact Evaluation fund).

Can personalized digital counseling improve consumer search for modern contraceptive methods?

This paper analyzes a randomized controlled trial of a personalized digital counseling intervention addressing informational constraints and choice architecture, cross-randomized with discounts for long-acting reversible contraceptives (LARCs), such as intrauterine devices (IUDs). The counseling intervention encourages shared decision-making (SDM) using a tablet-based app, which provides a tailored ranking of modern methods to each client according to their elicited needs and preferences. Take-up of LARCs in the status quo regime at full price was 11%, which increased to 28% with discounts. SDM roughly tripled the share of clients adopting a LARC at full price to 35%, and discounts had no incremental impact in this group. Neither intervention affected the take-up of short-acting methods, such as the pill. Consistent with theoretical models of consumer search, SDM clients discussed more methods in depth, which led to higher adoption rates for second- or lower-ranked LARCs. Our findings suggest that low-cost individualized recommendations can potentially be as effective in increasing unfamiliar technology adoption as providing large subsidies.

The short-term impacts of a schooling conditional cash transfer program on the sexual behavior of young women.

Recent evidence suggests that conditional cash transfer (CCT) programs for schooling are effective in raising school enrollment and attendance. However, there is also reason to believe that such programs can affect other outcomes, such as the sexual behavior of their young beneficiaries. Zomba Cash Transfer Program is a randomized ongoing CCT intervention targeting young women in Malawi that provides incentives (in the form of school fees and cash transfers) to current schoolgirls and recent dropouts to stay in or return to school. An average offer of US$10/month conditional on satisfactory school attendance - plus direct payment of secondary school fees - led to significant declines in early marriage, teenage pregnancy, and self-reported sexual activity among program beneficiaries after just one year of program implementation. For program beneficiaries who were out of school at baseline, the probability of getting married and becoming pregnant declined by more than 40 and 30%, respectively. In addition, the incidence of the onset of sexual activity was 38% lower among all program beneficiaries than the control group. Overall, these results suggest that CCT programs not only serve as useful tools for improving school attendance but may also reduce sexual activity, teen pregnancy, and early marriage.

Girl Empower - A gender transformative mentoring and cash transfer intervention to promote adolescent wellbeing: Impact findings from a cluster-randomized controlled trial in Liberia.

BACKGROUND: We evaluated Girl Empower - an intervention that aimed to equip adolescent girls with the skills to make healthy, strategic life choices and to stay safe from sexual abuse using a cluster-randomized controlled trial with three arms: control, Girl Empower (GE), and GE+. METHODS: GE delivered a life skills curriculum to girls aged 13-14 in Liberia, facilitated by local female mentors. In the GE + variation, a cash incentive payment was offered to caregivers for girls' participation in the program. We evaluated the impact of the program on seven pre-specified domains using standardized indices: sexual violence, schooling, sexual and reproductive health (SRH), psychosocial wellbeing, gender attitudes, life skills, and protective factors. FINDINGS: Participation rates in the program were high in both GE and GE+, with the average participant attending 28 out of 32 sessions. At 24 months, the standardized effects of both GE and GE+, compared to control, on sexual violence, schooling, psychosocial wellbeing, and protective factors were small (ß, ≤ 0.11 standard deviations [SD]) and not statistically significant at the 95% level of confidence. However, we found positive standardized effects on Gender Attitudes (GE: ß, 0.206 SD, p<0.05; GE+: ß, 0.228 SD, p<0.05), Life Skills (GE: ß, 0.224 SD, p<0.05; GE+: ß, 0.289 SD, p<0.01), and SRH (GE: ß, 0.244 SD, p<0.01; GE+: ß, 0.372 SD, p<0.01; F-test for GE = GE+: p = 0.075). INTERPRETATION: Girl Empower led to sustained improvements in several important domains, including SRH, but did not reduce sexual violence among the target population.

The heterogeneous effects of HIV testing.

An extensive multi-disciplinary literature examines the effects of learning one's HIV status on subsequent risky sexual behaviors. However, many of these studies rely on non-experimental designs; use self-reported outcome measures; or both. In this study, we investigate the effects of a randomly assigned home based HIV testing and counseling (HTC) intervention on risky sexual behaviors and schooling investments among school-age females in Malawi. We find no overall effects on HIV, Herpes Simplex Virus (HSV-2), or achievement test scores at follow-up. However, among the small group of individuals who tested positive for HIV, we find a large increase in the probability of HSV-2 infection, with this effect being stronger among those surprised by their test results. Similarly, those surprised by HIV-negative test results have significantly higher achievement test scores at follow-up, consistent with increased returns to investments in human capital.

Producing an improved geographic-methodology and evidence from three developing countries

This paper implements a methodology for estimating poverty in Ecuador, Madagascar and South Africa, at levels of disaggregation that to date have not generally been available. The methodology is based on a statistical procedure to combine household survey data with population census data, imputing into the latter a measure of per capita consumption from the former.