Mortality from road traffic accidents in Switzerland: longitudinal and spatial analyses

Road traffic accidents (RTA) are an important cause of premature death. We examined socio-demographic and geographical determinants of RTA mortality in Switzerland by linking 2000 census data to RTA mortality records 2000–2005 (ICD-10 codes V00–V99). Data from 5.5 million residents aged 18–94 years, 1744 study areas, and 1620 RTA deaths were analyzed, including 978 deaths (60.4%) in motor vehicle occupants, 254 (15.7%) in motorcyclists, 107 (6.6%) in cyclists, and 259 (16.0%) in pedestrians. Weibull survival models and Bayesian methods were used to calculate hazard ratios (HR), and standardized mortality ratios (SMR) across study areas.Adjusted HR comparing women with men ranged from 0.04 (95% CI 0.02–0.07) in motorcyclists to 0.43 (95% CI 0.32–0.56) in pedestrians. There was a u-shaped relationship with age in motor vehicle occupants and motorcyclists. In cyclists and pedestrians, mortality increased after age 55 years. Mortality was higher in individuals with primary education (HR 1.53; 95% CI 1.29–1.81), and higher in single (HR 1.24; 95% CI 1.05–1.46), widowed (HR 1.31; 95% CI 1.05–1.65) and divorced individuals (HR 1.62; 95% CI 1.33–1.97), compared to persons with tertiary education or married persons. The association with education was particularly strong for pedestrians (HR 1.87; 95% CI 1.20–2.91). RTA mortality increased with decreasing population density of study areas for motor vehicle occupants (test for trend p < 0.0001) and motorcyclists (p = 0.0021) but not for cyclists (p = 0.39) or pedestrians (p = 0.29). SMR standardized for socio-demographic and geographical variables ranged from 82 to 190.Prevention efforts should aim to reduce inequities across socio-demographic and educational groups, and across geographical areas, with interventions targeted at high-risk groups and areas, and different traffic users, including pedestrians.