title: Do suicide attempts occur more frequently in the spring too? A systematic review and rhythmic analysis.
abstract: BACKGROUND
  Seasonal variations in suicides have been reported worldwide, however, there may be a different seasonal pattern in suicide attempts. The aim of this study was to perform a systematic review on seasonality of suicide attempts considering potential interfering variables, and a statistical analysis for seasonality with the collected data.
  
  
  METHODS
  Observational epidemiological studies about seasonality in suicide attempts were searched in PubMed, Web of Science, LILACS and Cochrane Library databases with terms attempted suicide, attempt and season. Monthly or seasonal data available were evaluated by rhythmic analysis softwares.
  
  
  RESULTS
  Twenty-nine articles from 16 different countries were included in the final review. It was observed different patterns of seasonality, however, suicide attempts in spring and summer were the most frequent seasons reported. Eight studies indicated differences in sex and three in the method used for suicide attempts. Three articles did not find a seasonal pattern in suicide attempts. Cosinor analysis identified an overall pattern of seasonal variation with a suggested peak in spring, considering articles individually or grouped and independent of sex and method used. A restricted analysis with self-poisoning in hospital samples demonstrated the same profile.
  
  
  CONCLUSIONS
  Grouping diverse populations and potential analytical bias due to lack of information are the main limitations.
  
  
  CONCLUSIONS
  The identification of a seasonal profile suggests the influence of an important environmental modulator that can reverberate to suicide prevention strategies. Further studies controlling interfering variables and investigating the biological substrate for this phenomenon would be helpful to confirm our conclusion.
authors.affiliation: Federal University of Alagoas - Faculty of Medicine, Brazil.
authors.forename: Daniel Gomes
authors.initials: DG
authors.lastname: Coimbra
authors.affiliation: Federal University of Alagoas - Institute of Biological and Health Sciences, Brazil.
authors.forename: Aline Cristine
authors.initials: AC
authors.lastname: Pereira E Silva
authors.affiliation: Federal University of Alagoas - Institute of Biological and Health Sciences, Brazil.
authors.forename: Célio Fernando
authors.initials: CF
authors.lastname: de Sousa-Rodrigues
authors.affiliation: Federal University of Alagoas - Institute of Biological and Health Sciences, Brazil.
authors.forename: Fabiano Timbó
authors.initials: FT
authors.lastname: Barbosa
authors.affiliation: Federal University of Alagoas - Institute of Biological and Health Sciences, Brazil.
authors.forename: Diego
authors.initials: D
authors.lastname: de Siqueira Figueredo
authors.affiliation: Federal University of Alagoas - Institute of Biological and Health Sciences, Brazil.
authors.forename: José Luiz
authors.initials: JL
authors.lastname: Araújo Santos
authors.affiliation: Federal University of Alagoas - Institute of Biological and Health Sciences, Brazil.
authors.forename: Mayara Rodrigues
authors.initials: MR
authors.lastname: Barbosa
authors.affiliation: Federal University of Alagoas - Campus Arapiraca, Brazil.
authors.forename: Veronica
authors.initials: V
authors.lastname: de Medeiros Alves
authors.affiliation: Panic & Respiration Laboratory, Institute of Psychiatry, Federal University of Rio de Janeiro, National Institute for Translational Medicine (INCT-TM), Rio de Janeiro, Brazil.
authors.forename: Antonio Egidio
authors.initials: AE
authors.lastname: Nardi
authors.affiliation: Federal University of Alagoas - Faculty of Medicine, Brazil. Electronic address: deandrade.tiago@pq.cnpq.br.
authors.forename: Tiago Gomes
authors.initials: TG
authors.lastname: de Andrade
mesh_terms: D000328:Adult; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D064887:Observational Studies as Topic; D010507:Periodicity; D012621:Seasons; D012737:Sex Factors; D013406:Suicide, Attempted / Q000706:statistics & numerical data*
keywords: Cosinor; Season; Suicide attempt; Systematic review