Table 2. Categories of RCHD sources of outcome data in 46 studies where this was the sole source for at least one outcome.

Source	Number (%)
(i) Primary care data (all regional equivalents)	8 (17%)
(ii) HES (and/or regional equivalents)	27 (59%)
(iii) ONS (and/or regional equivalents)	27 (59%)
(iv) Data collected specifically for patient group or healthcare intervention (to include patient registries, ICNARC, ambulance, etc)	26 (57%)
(v) Other	5 (11%)