Health service indicators for radiology departments: how meaningful are they?

The Health Service Indicator (HSI) for Radiology Services in the UK is represented by a cost per case figure based on annual expenditure and workloads in individual departments. These show significant variations betweeen departments for a number of predictable reasons. Detailed analysis shows good correlation between population-based radiology costs and workloads and that departments with low cost per case values have above average workloads. The usefulness of the HSI cost per case is limited to identification of departments with unduly high or low values, thus allowing such departments to critically appraise their staffing and workload levels. Taken at face value, they can easily be misinterpreted as a measure of cost-effectiveness.