The damage to health caused by intimate partner violence demands effective responses from healthcare providers and healthcare systems worldwide. To date, most evidence for the few existing, effective interventions in use comes from high-income countries. Gupta et al. provide rare evidence of a nurse-delivered intimate partner violence screening, supportive care and referral intervention from a large-scale randomised trial in Mexican public health clinics. No difference was found in the primary outcome of reduction in intimate partner violence. There were significant short-term benefits in safety planning and mental health (secondary outcomes) for women in the intervention arm, but these were not sustained.This important study highlights the challenges of primary outcome choices in such studies, and further challenges for the sustainability of healthcare systems and healthcare provider interventions. These challenges include the role of theory for sustainability and the risk that baseline measures of intimate partner violence can wash out intervention effects. We emphasise the importance of studying the processes of adaptation, integration and coordination in the context of the wider healthcare system.Please see related article: https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-017-0880-y.