Ambulatory care sensitive conditions: terminology and disease coding need to be more specific to aid policy makers and clinicians.

OBJECTIVES: Ambulatory or primary care sensitive conditions (ACSCs) are those conditions for which hospital admission could be prevented by interventions in primary care. At present, different definitions of ACSCs are used for research and health policy analysis. This study aimed to explore the impact of different definitions of ACSCs and associated disease codes on analysis of health service activity. STUDY
DESIGN: Retrospective cross-sectional study using Hospital Episode Statistics (HES).
METHODS: All ACSCs identified by a literature search were documented. Conditions and codes were standardized using International Classification of Diseases (ICD) 10. A subset of ACSCs commonly used in England was compared with all 36 ACSCs identified by the search in a retrospective cross-sectional study using HES.
RESULTS: In total, 36 potential ACSCs were identified, which contained numerous subcategories. The most frequently used subset of ACSCs in the NHS only contains 19 ACSCs. There were 4,659,054 emergency admissions in England in 2005/6, of which 1,900,409 were ACSCs using the full set of 36 conditions. The proportion of these admissions attributable to the NHS subset of 19 ASCS was 35%. The underlying ICD10 codes used to define ACSCs vary widely across subsets of ACSCs used in the NHS. This impacts on rates of admission, length of stay and costs attributable to ACSCs.
CONCLUSIONS: Rates of hospital admission for ACSCs are increasingly used as a measure of the effectiveness of primary care. However, different conceptual interpretations of the term 'ACSC' and use of differing definitions and diagnostic codes impact on the proportion of admissions that are attributed as ACSCs. Some resolution of these inconsistencies is required for this measure to be more useful to decision makers.