Risk factors for suicide in Japan: A model of predicting suicide in 2008 by risk factors of 2007

Background: This study aims to comprehensively investigate the causal relationship between suicide and its risk factors in a longitudinal design. Methods: A model was derived in which suicide rate in 2008 was longitudinally and comprehensively predicted by potential risk factors recorded one year before (2007) which included personal and interpersonal factors, medical factors, economic factors, climate factors, alcoholic factors, and omega-3 fatty-acid factors. Results: In males, elderly population rate and complete unemployment rate predicted SMR of suicide significantly and positively whereas marriage rate and annual postal savings per person predicted SMR of suicide significantly and negatively. Also in females, complete unemployment rate predicted SMR of suicide significantly and positively whereas annual mean temperature predicted SMR of suicide significantly and negatively. Limitations: The limitations of this study are that predictions are based on the data of only the recent two years, that these epidemiological data cannot be always extrapolated to individuals, and that other factors should be taken into consideration to female suicide. Conclusions: The present findings suggest that male suicide may be accounted for by older age, more complete employment rate, less marriage rate and less annual postal savings whereas female suicide may be accounted for by more complete employment rate and lower annual mean temperature. (C) 2013 Elsevier B.V. All rights reserved.