The lack of a benchmark for measuring mistreatment makes it more complicated to compare the results of different studies. This lack stems not only from the fact that there is no universal definition of mistreatment, but also from the absence of validated measures for each form and type of mistreatment. In a meta-analysis of published studies from around the world, Yon et al. found that in the 12 months prior to data collection the pooled prevalence rate for overall mistreatment of older adults living in the community was 15.7%, i.e. 1 older adult in 6. In all, 11.6% of the respondents had been victims of psychological mistreatment; 6.8%, of financial mistreatment; 4.2%, of neglect; 2.6%, of physical mistreatment; and 0.9%, of sexual mistreatment . These findings were somewhat shocking to the international research community in this field, at least in the so-called developed countries that were reporting overall rates well below 10%.
In Canada, a study by Podnieks et al. identified a prevalence rate of 4%3 for mistreatment , while the General Social Survey  reported a rate of 7% in the 5 years prior to the survey. A study by McDonald reported a rate of 8.2% in the 12 months prior to the study . No studies have focused specifically on Québec, but AP-2 announced that a study will be conducted in the near future on the prevalence of mistreatment . This will make it possible to quantify the scope of the problem for the very first time.
No reliable data have been generated on the scope of mistreatment of older adults in residential or long-term care facilities. An analysis of 69 studies published on the subject identified many methodological problems: sample size, choice of participants, failure to consider structural factors, etc. . The authors suggested that a pilot project be conducted to develop reliable measurements. Europeans have suggested that it be compulsory to keep a register of situations of mistreatment within institutions ; however, this would pose major clinical and methodological challenges.