Measuring exposure to health messages in community-based intervention studies: a systematic review of current practices.

Accurately measuring exposure is critical to all intervention studies. The present review examines the extent to which best practices in exposure assessment are adhered to in community-based prevention and education studies. A systematic literature review was conducted examining community-based studies testing communication interventions, published in 2003-2007. Of 663 studies identified, 54 met all inclusion criteria and were reviewed for type of exposure assessment conducted (if any), use of exposure data in study analyses, and discussion of biases related to exposure assessment. Although a majority of studies (n = 38; 70%) assessed exposure, most of these used only a simple dichotomous measure (n = 31; 82%), less than half used exposure data to adjust intervention effects (n = 16; 42%), and only six (16%) addressed selective exposure as a possible source of bias. There is substantial room for improvement in measurement and analysis of exposure to communication in community-based disease prevention studies.