Suicide risk in relation to level of urbanicity--a population-based linkage study

The extent to which the high suicide rate in urban areas is influenced by exposures to risk factors for suicide other than urbanicity remains unknown. This population-based study aims to investigate suicide risk in relation to the level of urbanicity in the context of other factors, and to study the risk variation in a sex, age, and calendar year perspective.

The study is a nested case-control study comprising 21 169 suicides and 423 128 population controls matched for age and sex. Personal data on place of residence, socioeconomic status and psychiatric history were retrieved from various Danish longitudinal registers. Data were analysed with conditional logistic regression.

This study confirms that people living in more urbanized areas are at a higher risk of suicide than their counterparts in less urbanized areas. However, this excess risk is largely eliminated when adjusted for personal marital, income, and ethnic differences; it is even reversed when further adjusted for psychiatric status. Moreover, the impact of urbanicity on suicide risk differs significantly by sex and across age. Urban living reduces suicide risk significantly among men, especially young men, but increases the risk among women, especially women aged 24-35 or >65 years. In addition, during 1981-1997, the suicide risk associated with urbanicity remained rather constant among women, whereas it dropped significantly among men, a trend that seemingly gained strength during the last part of this period.

Suicide risk associated with urbanicity varies significantly by sex and age groups and recent years have seen a decline in the urban-rural disparities among men. The increased risk in urban areas can largely be explained by the effects of marital status, ethnics, income, and psychiatric status.