Helmet use by motorcyclists in four metropolitan areas of Mexico

To estimate the prevalence of helmet use among motorcyclists in four metropolitan areas of Mexico (Guadalajara, León, Monterrey, and Mexico City). In October 2009, helmet use was observed in 26,046 drivers and 3,971 passengers of motorcycles at several zones of busy traffic. The data were analyzed by means of a hierarchical logistic regression model. The adjusted probabilities of helmet use strongly differed among the four metropolitan areas: Mexico City: 79-91%; León: 99%; Guadalajara: 54-58%; Monterrey: 73-95%. The probability is lower in passengers (Odds Ratio [OR]: 0.15, with a 95%-confidence interval [CI] of 0.14-0.17) and in drivers who carry some passenger (OR: 0.49; 95% CI: 0.45-0.54, as compared to drivers without passengers), and higher in users of motorcycles for commercial use (OR: 1.76; 95% CI: 1.59-1.96, as compared to private use). Moreover, an estimated 44% of the motorcyclists used a type of helmet that was not officially approved and/or they did not properly adjust the device. This study shows that in Guadalajara, Monterrey, and Mexico City it is appropriate to start initiatives to promote helmet use in motorcyclists, particularly for passengers and drivers who transport one or more passengers.