Abstract: The search and selection process produced seven eligible studies which included a total of 1924 elderly participants and 740 other people. Four of the above seven categories of interventions were evaluated by included studies that varied in study design. Eligible studies of rehabilitation programmes, specific policies for elder abuse and legislation on elder abuse were not found. All included studies contained a control group, with five of the seven studies describing the method of allocation as randomised. We used the Cochrane 'Risk of bias' tool and EPOC assessment criteria to assess risk of bias. The results suggest that risk of bias across the included body of research was high, with at least 40% of the included studies judged as being at high risk of bias. Only one study was judged as having no domains at high risk of bias, with two studies having two of 11 domains at high risk. One study was judged as being at high risk of bias across eight of 11 domains. All included studies were set in high-income countries, as determined by the World Bank economic classification (USA four, Taiwan one, UK two). None of the studies provided specific information or analysis on equity considerations, including by socio-economic disadvantage, although one study was described as being set in a housing project. One study performed some form of cost-effectiveness analysis on the implementation of their intervention programmes, although there were few details on the components and analysis of the costing. We are uncertain whether these interventions reduce the occurrence or recurrence of elder abuse due to variation in settings, measures and effects reported in the included studies, some of which were very small and at a high risk of bias (low- and very low-quality evidence).Two studies measured the occurrence of elder abuse. A high risk of bias study found a difference in the post-test scores (P value 0.048 and 0.18). In a low risk of bias study there was no difference found (adjusted odds ratio (OR) =0.48, 95% 0.18 to 1.27) (n = 214). For interventions measuring abuse recurrence, one small study (n = 16) reported no difference in post-test means, whilst another found higher levels of abuse reported for the intervention arms (Cox regression, combined intervention hazard ratio (HR) = 1.78, alpha level = 0.01). It is uncertain whether targeted educational interventions improve the relevant knowledge of health professionals and caregivers (very low-quality evidence), although they may improve detection of resident-to-resident abuse. The concept of measuring improvement in detection or reporting as opposed to measuring the occurrence or recurrence of abuse is complicated. An intervention of public education and support services aimed at victims may also improve rates of reporting, however it is unclear whether this was due to an increase in abuse recurrence or better reporting of abuse.The effectiveness of service planning interventions at improving the assessment and documentation of related domains is uncertain. Unintended outcomes were not reported in the studies. There is inadequate trustworthy evidence to assess the effects of elder abuse interventions on occurrence or recurrence of abuse, although there is some evidence to suggest it may change the combined measure of anxiety and depression of caregivers. There is a need for high-quality trials, including from low- or middle-income countries, with adequate statistical power and appropriate study characteristics to determine whether specific intervention programmes, and which components of these programmes, are effective in preventing or reducing abuse episodes among the elderly. It is uncertain whether the use of educational interventions improves knowledge and attitude of caregivers, and whether such programmes also reduce occurrence of abuse, thus future research is warranted. In addition, all future research should include a component of cost-effectiveness analysis, implementation assessment and equity considerations of the specific interventions under review.

Plain-language summary: We found seven studies from our search of 19 databases. All together, the studies included 1924 elderly participants and 740 people (such as carers or nursing home staff) with whom they interact. These studies described methods of preventing or reducing elder abuse with elderly people. The studies included programs and strategies that took place in many different settings (home, community, institutions) although only in high-income countries. The programs and strategies identified included methods to increase detection in clinical practice and community settings, victim support, increasing awareness of elder abuse and delivering training programs aimed at building skills in care providers. Most studies described changes in knowledge and attitudes, with very few measuring the occurrence or reoccurrence of abuse. The study durations ranged from six to 24 months. The included studies suggest it is uncertain whether targeted educational interventions improve the knowledge of health and allied professionals and caregivers about elder abuse. It is unclear whether any improved knowledge actually leads to changes in the way they behave thereafter, and whether this leads to the elderly being abused less. Similarily, supporting and educating elderly victims of abuse appears to lead to more reporting of abuse, however it is unclear if the higher reporting meant more abuse occurred or a greater willingness to report the abuse as it occurred. None of the studies reported any unintended outcomes of these approaches. Most of the evidence was low or very low quality (we cannot assume the findings of these studies are true) and limits our understanding of what strategies or programs work best to decrease or prevent elder abuse. Many of the studies were unclear in the design, too small in size or not similar enough in their findings to have full confidence in the findings.