title: Seasonality of suicide in Shandong China, 1991-2009: associations with gender, age, area and methods of suicide.
abstract: BACKGROUND
  Whether suicide in China has significant seasonal variations is unclear. The aim of this study is to examine the seasonality of suicide in Shandong China and to assess the associations of suicide seasonality with gender, residence, age and methods of suicide.
  
  
  METHODS
  Three types of tests (Chi-square, Edwards' T and Roger's Log method) were used to detect the seasonality of the suicide data extracted from the official mortality data of Shandong Disease Surveillance Point (DSP) system. Peak/low ratios (PLRs) and 95% confidence intervals (CIs) were calculated to indicate the magnitude of seasonality.
  
  
  RESULTS
  A statistically significant seasonality with a single peak in suicide rates in spring and early summer, and a dip in winter was observed, which remained relatively consistent over years. Regardless of gender, suicide seasonality was more pronounced in rural areas, younger age groups and for non-violent methods, in particular, self-poisoning by pesticide.
  
  
  CONCLUSIONS
  There are statistically significant seasonal variations of completed suicide for both men and women in Shandong, China. Differences exist between residence (urban/rural), age groups and suicide methods. Results appear to support a sociological explanation of suicide seasonality.
authors.affiliation: School of Public Health, Queensland University of Technology, Australia.
authors.forename: Jiandong
authors.initials: J
authors.lastname: Sun
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Guo
authors.forename: Jixiang
authors.initials: J
authors.lastname: Ma
authors.forename: Jiyu
authors.initials: J
authors.lastname: Zhang
authors.forename: Cunxian
authors.initials: C
authors.lastname: Jia
authors.forename: Aiqiang
authors.initials: A
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002681:China / Q000453:epidemiology; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012424:Rural Population; D012621:Seasons; D012737:Sex Factors; D013405:Suicide / Q000706:statistics & numerical data*; D014505:Urban Population; D055815:Young Adult