Suicides during the Swedish midsummer holiday: analysis of cause of death data 1980–2018

Abstract

Introduction

Previous studies have demonstrated increased suicide rates on holidays such as New Year, nationally and internationally. Comparable to New Year’s Eve, Swedish Midsummer is a major holiday, linked to high levels of alcohol consumption in the population. We, therefore, hypothesized that suicides and deaths with undetermined intent would increase during the Midsummer celebration.

Methods

We used a retrospective death registry design to investigate all suicides that occurred on Midsummer’s Eve (ME), Midsummer’s Day (MD) and 28 adjacent days (AD) during 1980–2018. Data were stratified by diagnosis type, sex and age, and was analyzed with paired t-tests, Poisson regression, and time-series charts with 95% confidence intervals.

Results

During the 30-day investigation period, the observed average was 4.3 deaths per day (23.3% cases with undetermined intent). ME, but not MD, was associated with significantly fewer suicides compared to AD (−1.08 deaths, p < .01). ME, but not MD, was simultaneously associated with more deaths with undetermined intent (+0.58 deaths, p = .007). No moderating sex or age effects were found. Descriptive statistics showed that poisonings, drownings and traffic-related injuries were common among the undetermined ME cases.

Discussion

The study found that suicide decreases and deaths with undetermined intent increases on ME. The findings are interpreted considering that substance use may affect both suicidal intentions and diagnosis classifications. Social and cultural support and holiday anticipations might also account for suicidal behaviors on ME.

Keywords:

• Suicide
• undetermined intent
• midsummer
• holiday
• alcohol use

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data used for this study was provided by the Swedish National Board of Health and Welfare, in 2019. For ethical reasons, we do not provide raw data from the Swedish cause of death registry (see ethical statement in section: Methods and materials). Other methodological information to support replication by independent researchers is available from the corresponding author upon request.

Additional information

Notes on contributors

Sebastian Hökby

Sebastian Hökby, MA psychology; PhD student at National Centre for Suicide Research and Prevention, Department of Learning, Informatics, Management and Ethics, Karolinska Institutet; and Research assistant at National Centre for Suicide Research and Prevention, Centre for Health Economics, Informatics and Health Services Research, Stockholm Health Care Services.

Joakim Westerlund

Joakim Westerlund, PhD; Associate professor at Department of Psychology, Stockholm University; and Researcher at National Centre for Suicide Research and Prevention, Centre for Health Economics, Informatics and Health Services Research, Stockholm Health Care Services.

Bianca Blazevska

Bianca Blazevska, Research assistant at National Centre for Suicide Research and Prevention, Centre for Health Economics, Informatics and Health Services Research, Stockholm Health Care Services.

Gergö Hadlaczky

Gergö Hadlaczky, PhD; Researcher and Head of National Centre for Suicide Research and Prevention, Centre for Health Economics, Informatics and Health Services Research, Stockholm Health Care Services; and adjunct researcher at National Centre for Suicide Research and Prevention, Department of Learning, Informatics, Management and Ethics, Karolinska Institutet.