Conceptual and methodological aspects in the study of hospitalizations for ambulatory care sensitive conditions.

Hospitalization rates for Ambulatory Care Sensitive Conditions have been used to assess effectiveness of the first level of health care. From a critical analysis of related concepts, we discuss principles for selecting a list of codes and, taking the example of the Brazilian Family Health Program, propose a methodological pathway for identifying variables in order to inform statistical models of analysis. We argue that for the indicator to be comparable between regions, disease codes should be selected based on sensitivity and specificity principles, not on observed disease frequency. Rates of hospitalization will be determined, at a distal level, by the socio-economic environment and their effect on the social and demographic structure. Timely and effective care depends on the organization of health services, their availability and access barriers, which depend on the ways health and related technology are conceptualised and on their adherence to the biomedical model or to the Primary Health Care (PHC) principles; performance indicators of the health system will be the proximal determinants. This indicator is potentially useful for primary care evaluation. The historical reconstruction of PHC improves the analysis of the indicator variability.