Data quality Hospital Episode Statistics (HES) are compiled from data sent by over 300 NHS trusts, and primary care trusts (PCTs) in England. Data are also received from a number of independent sector organisations for activity commissioned by the English NHS. The NHS Information Centre for health and social care liaises closely with these organisations to encourage submission of complete and valid data and seeks to minimise inaccuracies and the effect of missing and invalid data via HES processes. While this brings about improvement over time, some shortcomings remain. Finished admission episodes A finished admission episode is the first period of in-patient care under one consultant within one health care provider. Please note that admissions do not represent the number of in-patients, as a person may have more than one admission within the year. Finished consultant episode (FCE) An FCE is defined as a period of admitted patient care under one consultant within one health care provider. Please note that the figures do not represent the number of patients, as a person may have more than one episode of care within the year. Main procedure/intervention The main procedure/intervention is the first recorded procedure or intervention in the HES data set and is usually the most resource intensive procedure or intervention performed during the episode. Heart operations K01-K78 Secondary procedure As well as the main operative procedure, there are up to 11 (three prior to 2002-03) secondary operation fields in Hospital Episode Statistics (HES) that show secondary or additional procedures performed on the patient during the episode of care. Time waited (days) Time waited statistics from Hospital Episode Statistics (HES) are not the same as the published waiting list statistics. HES provides counts and time waited for all patients admitted to hospital within a given period whereas the published waiting list statistics count those waiting for treatment on a specific date and how long they have been on the waiting list. Also, HES calculates the time waited as the difference between the admission and decision to admit dates. Unlike published waiting list statistics, this is not adjusted for self-deferrals or periods of medical/social suspension. The IC have provided the mean (average) and median (middle in ranking) days waited where there was a main procedure of 'heart operation' in 2005-06 and 2006-07. The median figures are a better proxy to the average time waited as mean figures can cloud the real picture as some anomalies (long-waiters) may be artificially increasing the average. Ungrossed data Figures have not been adjusted for shortfalls in data (i.e. the data are ungrossed). Source: Hospital Episode Statistics (HES), The NHS Information Centre for Health and Social Care.