Background One of the key recommendations of the 2005 policy document “Taking Healthcare to the patient” was that the category B 19-min response standard be replaced with more clinically focused performance measures. Before developing these new measures a clear description of the nature and type of calls within category B was needed in order to understand the case-mix of this group. We have conducted a descriptive observational study of category B ambulance calls.

Methods The study was conducted in two parts. First, a national survey of all ambulance services in England was conducted requesting information on total number of category B calls for 1 year (2007/2008) and the numbers allocated to each AMPDS dispatch category. Secondly, we obtained 2 months of category B call dispatch records and scanned anonymised clinical patient record data from one ambulance service. This information was used to describe clinical acuity and frequency of clinical assessment and interventions.

Results

1. National survey—7/11 ambulance services returned data. We found that 50% of the total category B call volume is accounted for by 5 of the 32 main dispatch categories. Diabetic problems and falls were the main categories.

2. Analyses of clinical data—After removing duplicate records 26 882 cases were used. A quarter (25%) of cases had no assessment or intervention other than basic vital sign measurement, 50% had additional clinical assessment but no intervention and 25% required an intervention. The most frequent intervention was oxygen administration. Only 10% of cases required drugs, airway management or other procedures.

Conclusions Category B calls comprise a population of patients without time dependant conditions and response time is therefore a poor indicator of the quality of care for this patient group.