Spatial analysis of factors influencing choice of paediatric practice for mothers from low-income and minority populations.

AIM: Publicly reported quality data theoretically enable parents to choose higher-performing paediatric practices. However, little is known about how parents decide where to seek paediatric care. We explored the relationship between geographic factors, care quality and choice of practice to see if the decision-making process could be described in terms of a 'gravity model' of spatial data.

METHODS: In the context of a randomised controlled trial, we used a geographic information system to calculate flow volume between practice locations and participants' homes, to locate subjects within a census tract, to determine distances between points and to perform exploratory mapping. Generalised linear modelling was then used to determine whether the data fit a gravity model, which is a spatial model that evaluates factors impacting travel from one set of locations to another.

RESULTS: A total of 662 women and 52 paediatric practices were included in the analysis. Proximity of a practice to home was the most important factor in choosing a practice (Z = -15.01, P < 0.001). Practice size was important to a lesser extent, with larger practices more likely to be chosen (Z = 8.96, P < 0.001). A practice's performance on quality measures was associated with choice only for women who had received an intervention to increase use of quality data (Z = 2.51, P < 0.05).

CONCLUSIONS: The gravity model and the concept of flow can help explain the choice of paediatric practice in a predominantly low-income, racially ethnic minority (non-White) urban population. This has important ramifications for the potential impact of publicly reported quality data.