Assessing the cost-effectiveness of economic strengthening and parenting support for preventing violence against adolescents in South Africa: An economic modelling study using non-randomised data.

There is limited evidence around the cost-effectiveness of interventions to prevent violence against children in low- and middle-income countries. We developed a decision-analytic model to estimate the cost-effectiveness of 1) a community outreach intervention to link eligible households to anti-poverty cash grants, and 2) a group-based parenting support intervention, and 3) a group-based parenting support plus linkage of eligible households to anti-poverty cash grants intervention for preventing adolescent violence victimisation in Mpumalanga province, South Africa. The target population was families with an adolescent living below the national food poverty line. Modelled violence outcomes were emotional, physical, and sexual abuse. Intervention effectiveness was conditional on interventions effect on two evidence-based protective factors for adolescent violence: food security and caregiver supervision. Cost-effectiveness ratios were expressed per DALY averted and evaluated against a South Africa-specific willingness-to-pay threshold. We varied model parameters to consider routine service delivery versus trial-based costing, and population-average versus high prevalence of violence. For routine service delivery costing, both community grant outreach and parenting support interventions were cost-effective at population-average prevalence (ACER=USD2,650, and ACER=USD2,830 per DALYs averted, respectively), and high prevalence of violence (ACER=USD1,330 and ACER=USD2,305 per DALYs averted, respectively). The incremental cost-effectiveness of adding grant linkage to parenting support was USD271 and USD177 at population-average and high prevalence of violence, respectively. For trial-based costing, none of the interventions were cost-effective at population-average prevalence of violence, and only community grant outreach was cost-effective at high prevalence of violence (ACER=USD2400 per DALY averted). Cost-effectiveness estimates are expected to be conservative based on our only modelling intervention effects on three violence outcomes via two protective factors. Findings indicate that investments in community grant outreach, and parenting support interventions are likely to be cost-effective for preventing adolescent violence. Adding a grant linkage component to parenting support would enhance this approaches cost-effectiveness.