A ssociation of Public Health Observatories Hospital Activity data Roy Maxwell SWPHO & Bristol University Dr Richard Wilson Sandwell PCT

The Department of Health requires accurate data on all patients who were either admitted to NHS hospitals, or treated as out-patients or as A&E attendees in NHS hospitals. The data include private patients treated in NHS hospitals, and NHS patients treated electively in the independent sector and overseas. Department of Health requirements regarding hospital activity data

Secondary Uses Service (SUS) Single repository of person and care event level data relating to the NHS care of patients Data currently derived from the commissioning datasets In future, wherever possible, data will be captured automatically from NHS operational systems Ultimately, should cover NHS-commissioned care provided in all settings Access is role-based & limited, perhaps only for your own PCT

SUS to HES Healthcare providers supply local administrative and clinical data to the Secondary Uses Service (SUS), which is copied to a SUS database.Secondary Uses Service At pre-arranged times during the year, SUS take an extract from their database and send it to HES. Data on SUS will continue to change, but HES data are fixed. HES data validated and cleaned before deriving new items and making the information available.

What is HES? National record of day-case, in-patient, A&E, and out-patient care by providers of healthcare in England for NHS patients Separate databases for emergency, and out-patient care (not covered in this presentation) Un-interrupted period covering 18 years from 1990/1 to 2008/9 A record of –Events: the episode –Diagnosis and external cause – ICD (9 & 10) –Operations and procedures – OPCS4 In excess of 200 million episodes of care

Deaths Tertiary care (specialist) Primary care, prescribing, NHS Direct, screening Secondary care, emergency, elective, in-patient, day-case Ambulance pick up, secondary care interface (waiting lists). A&E and out-patients. HES & the health pyramid

Strengths Probably the second largest 'medical' database in the world after medicare/medi-aid (USA): 200 million + episodes Covers population of approx 50,000,000 + (principally England) Covers all NHS care ~ 90-95% of all in-patient care Un-interrupted period covering 17 years from 1990/1 to 2008/9 Resident and registered populations Geographically and temporally referenced Diagnoses & procedures coded using ICD9, ICD10 & OPCS4 coding frames

Limitations A&E and out-patient activity (only recently added and poorly recorded at present) Non-surgical interventions (drugs) not recorded Private care in private institutions (therefore an incomplete record of procedures where private practice is much used, eg joint replacement Boundary changes and population denominators (everybody ’ s nightmare, not just HES) Coding issues (e.g. ethnicity) – problem of all databases

Coverage In excess of 82 fields of information including: Linkage variables such as ID and SPELL identifiers Age, sex Dates of admission and discharge Diagnoses (ICD9 & ICD10) – up to 20 diagnosis fields Procedures performed (OPCS4) – up to 24 fields Area of residence, area of treatment Waiting times Type of admission e.g. emergency, elective Health Resource Groups (HRGs)

HES and Public Health: a different way of thinking Consider the database as a record of acute & chronic morbidity in our population. –First episodes (admissions) become incidents (not necessarily incidence / prevalence) –Unique NHS Numbers become patients (not always unique) –Procedures, discharges, deaths, or other events become outcomes –Admissions over years become a longitudinal study Consider it as the largest health survey of your local population. –Which residents (sex, age, area) had the highest accident rates in our PCT? –What is the variation in admission rates for CHD or CABGs in our PCT? Are there issues of equitable access?

Considerations Appropriateness – is HES the right tool? –Is the event likely to turn up in HES? Looking at emergency events requiring hospital stay, is the condition clearly recorded? –Are all hospitals likely to have similar treatment regimes? Medical Assessment Units? Consultants with an interest? –Missing events - will all those who die be included? Could always check public health mortality files –Private provision? Emergencies rather than elective care so should not impact on this study

What’s a record? At least one record for each patient’s stay in hospital (either day case or in-patient) A record reflects a patient’s period of care under a consultant, known as a consultant episode A patient’s SPELL in hospital may comprise of more than one episode

Admissions vs. Episodes 1 Discharge 4 Episodes

Episodes and Spells

Why link Episodes? Principally to: analyse patient care throughout a spell in hospital e.g. number of patients undergoing amputations who are also recorded as having diabetes identify repeat admissions by a patient the information you’re looking for may not appear on all episodes e.g. drug use/misuse

Learning outcomes Clearer understanding of HES Clearer understanding of appropriate use