Epidemiología analítica de la accidentalidad en ciclistas en España (analytical epidemiology of road crashes involving cyclists in Spain)

Laburpena

This Doctoral Thesis is devoted to the study of the analytical epidemiology of the likelihood of involvement in a traffic accident for cyclists in Spain, an important health problem which has not been studied extensively in our country before. Using the Registry of Traffic Accidents with Victims (supported by the Spanish General Traffic Directorate), we aimed: 1) to quantify the association of age and gender with the intensity of bicycle use; 2) to estimate the changes in the magnitude of association of age and gender with risk of involvement in a traffic accident while cycling before and after adjustment for intensity of bicycle use; 3) to quantify the association of person- and vehicle-dependent factors with the risk of causing a traffic accident involving a cyclist; and 4) to quantify the percent contribution of exposure, likelihood of involvement in an accident and fatality to differences between age and gender groups in mortality rates from traffic accidents involving cyclists. To obtain the proper results, we used different analytical strategies (i.e. logistic regression, Poisson regression, etc.) on the basis of the following approaches: quasi-induced exposure method and decomposition analysis. After that, several facts can be concluded. In Spain, the intensity of exposure to bicycle use is greater in younger age groups and in males; and the main differences in crude likelihood of involvement in an accident among age and gender groups depend on the association of age and gender with exposure. Also, in motor vehicle drivers, the risk of causing a collision with a cyclist was greater for older drivers, those driving under the influence of alcohol or drugs, and those who did not use safety devices. Responsibility for cyclist involvement in a collision was associated with male gender, young age, use of alcohol or drugs, non-use of a helmet, and brake or light defects in the bicycle. However, in a collision between a bicycle and a pedestrian, female cyclists had a greater risk of causing the collision with the pedestrian. Finally, the mortality rate from traffic accidents involving cyclists increased with age and was greater in males. The relative contribution of exposure, likelihood of involvement in an accident and fatality to the magnitude of the mortality rate varied clearly with age and gender. The knowledge generated by this thesis may contribute to the application of different interventions aimed to reduce the harmful effects of riding a bicycle.