Evaluating the effectiveness of health promotion policy: changes in the law on drinking and driving in California.

The purpose of the study was to determine the utility of general population health surveillance data for evaluating broad policy changes that relate to health promotion. Data were drawn from the United States (US) Behavioral Risk Factor Surveillance System (BRFSS) for one US state, California. Because these data are collected frequently and continually, a quasi-experimental approach to the evaluation was possible using a type of interrupted time series analysis or longitudinal impact analysis. A statistically significant decrease in the number of declared episodes of drinking and driving was found after enactment of new state policy. These findings were compared and found consistent with another study in California that examined the effect of changes in the law on alcohol-related traffic accidents. Our findings suggest that data from a behavioral surveillance system, in this case the BRFSS, are useful to evaluate the effect of a health promotion intervention. Further, the study demonstrates the utility of comparing different data sources when assessing a population-wide change in health promotion policy.