Impact of some types of mass gatherings on current suicide risk in an urban population: statistical and negative binominal regression analysis of time series.
BACKGROUND
Many studies have investigated the impact of a wide range of social events on suicide-related behaviour. However, these studies have predominantly examined national events. The aim of this study is to provide a statistical evaluation of the relationship between mass gatherings in some relatively small urban sub-populations and the general suicide rates of a major city.


METHODS
The data were gathered in the Ukrainian city of Dnipropetrovsk, with a population of 1 million people, in 2005-2010. Suicide attempts, suicides, and the total amount of suicide-related behaviours were registered daily for each sex. Bivariate and multivariate statistical analysis, including negative binomial regression, were applied to assess the risk of suicide-related behaviour in the city's general population for 7 days before and after 427 mass gatherings, such as concerts, football games, and non-regular mass events organized by the Orthodox Church and new religious movements.


RESULTS
The bivariate and multivariate statistical analyses found significant changes in some suicide-related behaviour rates in the city's population after certain kinds of mass gatherings. In particular, we observed an increased relative risk (RR) of male suicide-related behaviour after a home defeat of the local football team (RR = 1.32, p = 0.047; regression coefficient beta = 0.371, p = 0.002), and an increased risk of male suicides (RR = 1.29, p = 0.006; beta =0.255, p = 0.002), male suicide-related behaviour (RR = 1.25, p = 0.019; beta =0.251, p < 0.001), and total suicide-related behaviour (RR = 1.23 p < 0.001; beta =0.187, p < 0.001) after events organized by the new religious movements.


CONCLUSIONS
Although football games and mass events organized by new religious movements involved a relatively small part of an urban population (1.6 and 0.3%, respectively), we observed a significant increase of the some suicide-related behaviour rates in the whole population. It is likely that the observed effect on suicide-related behaviour is related to one's personal presence at the event rather than to its broadcast. Our findings can be explained largely in terms of Gabennesch's theory of the 'broken-promises effect' with regard to intra- and interpersonal conflict and, in terms of crowd behaviour effects.
Scientific Centre 'Medical Technologies', 52A/88 Komsomolskaya str,, Dnipropetrovsk 49000, Ukraine. aniko@a-teleport.com.
Vasiliy S
VS
Usenko
Sergey N
SN
Svirin
Yan N
YN
Shchekaturov
Eduard D
ED
Ponarin
D003441:Crowding; D005260:Female; D005538:Football; D006801:Humans; D008297:Male; D008399:Mass Behavior; D012044:Regression Analysis; D012067:Religion; D012307:Risk Factors; D012916:Soccer; D012919:Social Behavior; D059020:Suicidal Ideation; D013405:Suicide; D013406:Suicide, Attempted; D014455:Ukraine; D014505:Urban Population; D014754:Violence