Use of ethnographic research for instrument development in a case-control study of immunization use in Haiti

A rapid ethnographic assessment of barriers to health service utilization was conducted to identify maternal factors predicting use of child immunizations in Haiti. Methods included four focus group interviews, four natural group interviews, individual interviews with 14 health care providers and participant observation at vaccination posts. Analysis of qualitative data identified five categories of maternal factors associated with immunization use: competing priorities, low motivation, socioeconomic constraints, perceived accessibility of services, fears about health or social consequences and knowledge and folk beliefs related to vaccines. Selected variables among these factors were incorporated into a survey instrument designed to compare mothers of completely vaccinated children (cases) with mothers of incompletely vaccinated children (controls). The questionnaire was administered to 299 randomly selected mothers (217 cases, 82 controls). Bivariate and multivariate analyses found that of the factors identified through ethnographic research, only vaccine-related knowledge was significantly associated with immunization status. The utility and constraints of using ethnographic research for instrument development in epidemiological studies are discussed.