This paper is aimed to introduce the definition and application of Population Impact Measures (PIMs). The PIMs use Number Need to Treat (NNT) for reference and generalize the variables of clinical research to interest population, which then can be used to measure the effectiveness of interventions and the harmfulness of risk factors, so as to provide evidence for making public health policy. Of the PIMs, the variables used for measuring the effectiveness of interventions include Disease Impact Number (DIN), Population Impact Number (PIN) and Number of Events Prevented in your Population (NEPP); The variables used for measuring the harmfulness of risk factors include Exposure Impact Number (EIN), Exposed Cases Impact Number (ECIN), Population Impact Number (PIN), Case Impact Number (CIN) and Population Impact Number of Eliminating a Risk factor (PIN-ER-t).
Objective To reflect the correlation between social support and mental health of the aged through the Pearson correlation coefficient. Methods Databases including PubMed, SpringerLink, EMbase, The Cochrane Library, VIP, WanFang Data and CNKI were searched from inception to October, 2011 to collect literature on the correlation between social support and mental health of the aged. The studies were screened according to the inclusion and exclusion criteria. After extracting data and assessing the quality of the included studies, meta-analysis was conducted using RevMan 5.0 software. Results Of the 2 396 identified studies, 4 studies were included. The results showed that 4 studies were not high in the overall quality. The total score of social support of the elderly and its three dimensions were related to mental health. Among 9 factors associated with mental health, somatization, depression and anxiety were weakly correlated to the objective support while the others were extremely weakly correlated. Anxiety and phobic anxiety were weakly correlated to the subjective support while the others were extremely weakly correlated. Phobic anxiety was weakly correlated to the utilizing degree while the others were extremely weakly correlated. Somatization, anxiety and phobic anxiety were weakly correlated to the total score of social support while the others were extremely weakly correlated. Conclusion Social support probably improves mental health of the aged to some extent.