Impact of some types of mass gatherings on current suicide risk in an urban population: statistical and negative binominal regression analysis of time series

摘要

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? 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.