Seasonality of suicide in the city of Sao Paulo, Brazil, 1979-2003.
OBJECTIVE
To evaluate suicide seasonality in the city of São Paulo within an urban area and tropical zone.


METHODS
Suicides were evaluated using the chi-square test and analysis of variance (ANOVA) by comparing monthly, quarterly and half-yearly variations, differentiating by gender. Analyses of time series were carried out using the autocorrelation function and periodogram, while the significance level for seasonality was confirmed with the Fisher's test.


RESULTS
The suicides of the period between 1979 and 2003 numbered 11,434 cases. Differences were observed in suicides occurring in Spring and Autumn for the total sample (ANOVA: p-value = 0.01), and in the male sample (ANOVA: p-value = 0.02). For the analysis of time series, seasonality was significant only for the period of 7 months in the male sample (p-value = 0.04).


CONCLUSIONS
In this study, no significant seasonal differences were observed in the occurrences of suicides, with the exception of the male sample. The differences observed did not correspond with the pattern described in studies carried out in temperate zones. Some of the climatic particularities of the tropical zone might explain the atypical pattern of seasonality of suicides found in large populations within an urban area and tropical zone.
Bando
Daniel Hideki
DH
Department of Clinical Medicine, School of Medicine, Universidade de São Paulo, São Paulo, SP, Brazil. [corrected]
Scrivani
Hommenig
H
Morettin
Pedro Alberto
PA
Teng
Chei Tung
CT
D000704:Analysis of Variance; D001938:Brazil / Q000453:epidemiology; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D008297:Male; D012621:Seasons; D017678:Sex Distribution; D012737:Sex Factors; D013405:Suicide / Q000706:statistics & numerical data*; D014329:Tropical Climate