How often are adverse events reported in English hospital statistics?
BMJ 2004; 329 doi: https://doi.org/10.1136/bmj.329.7462.369 (Published 12 August 2004) Cite this as: BMJ 2004;329:369Data supplement
How often are adverse events reported in hospital statistics?
REFERENCES
w1 Emslie S. Risk management in the National Health Service in England. International Organization for Standards General Assembly 2001, Sydney. www.iso.ch/iso/en/commcentre/presentations/ga/gaopen/2001risk/ga01risk-emslie.ppt
w2 National Patient Safety Agency. www.npsa.nhs.uk
w3 World’s first national patient safety reporting system launched in England and Wales. NPSA press release 24 Feb 2004. http://81.144.177.110/npsa/display?contentId=2790
w4 Michel P, Quernon JL, Sarasqueta A, Scemama O. Comparison of three methods for estimating rates of adverse events and rates of preventable adverse events in acute care hospitals. BMJ 2004;328:199.
w5 Wolff AM. Limited adverse occurrence screening: using medical record review to reduce hospital adverse patient events. Med J Am 1996;164:458.
w6 Steel K, Gertman PM, Crescenzi C, Anderson J. Iatrogenic illness on a general medical service at a University hospital. N Engl J Med 1981;304:638-42 .
w7 Reporting of adverse events in routinely collected data sets in Australia. Australian Institute of Health and Welfare, 2001. www.aihw.gov.au/publications/workingpapers/hwp03.pdf
[posted as supplied by authors]
The Dr Foster case note is based on analysis of Hospital Episode Statistics (HES). This is data that is routinely collected within the health service for administrative purposes and not specifically for clinical audit. There may be issues around coverage, completeness and accuracy that need to be considered when interpreting the results. In addition, the capacity to adjust for confounding factors is in general limited to the information available in the data, although where appropriate, we are able to adjust by socio-economic deprivation using the postcode of residence.
HES data are submitted by all NHS hospital trusts in England and capture all admissions, both inpatients and day cases, and also include deaths occurring in hospital, recording details such as the patient’s age and diagnosis and any operations they had. The data are in the form of consultant episodes (the continuous period during which the patient is under the care of one consultant), which need to be linked into "spells" or admissions for some analyses. About 10% of spells comprise more than one episode, and the patient’s method and date of discharge need to be derived from the final episode in the spell.
Data fields can contain missing or invalid values and spells may be incomplete. The following describes in detail, the processing of HES fields (given in italicised capitals) undertaken for Dr Foster analyses.
HES data are maintained in the Dr Foster Unit at Imperial College London within the programming language and statistics package SAS (Version 8.0).
Episodes are assumed to be duplicates if they have the same combination of provider, date of birth, sex, postcode, date of admission and episode number (PROCODE, DOB, SEX, HOMEADD, EPISTART, EPIEND, EPIORDER). Duplicates are excluded at this stage.
Some spells have the same date of admission (ADMIDATE) but different dates of discharge (DISDATE). This is not valid unless the patient was discharged and readmitted on the same day, and the spell with the earliest ADMIDATE was arbitrarily taken to be the valid one. Episodes relating to the invalid spell are excluded at this stage.
Where analyses require episodes linked together to form spells, for years before 2000/1, records are assumed to belong to the same person if they match on date of birth, sex and postcode (DOB, SEX, HOMEADD) as the NHS number is not complete or accurate enough. Episodes with invalid DOB (recorded by HES as 15th Oct 1582) or SEX (i.e. not ‘1’ or ‘2’) are excluded at this stage. From 2000/1 we have been given HESID, derived by the Department of Health, and have been using this as a patient identifier. Only ages within the ranges 1-120 and 7001-7007 (special values to indicate age in months for children under 1 year) are considered valid.
Also excluded at this stage are unfinished episodes (EPISTAT=1), unknown/invalid method of admission (ADMIMETH <> 11,12,13,21,22,23,24,28,81). Episode linkage is not of course performed on day cases, which are discarded for projects involving only inpatients.
Remaining episodes are sorted by provider, date of birth, sex, postcode, date of admission, date of discharge and episode number (PROCODE, DOB, SEX, HOMEADD, ADMIDATE, DISDATE, EPIORDER). Episodes are not required to be in strict sequence, only in chronological order. For example, if the first one had EPIORDER=01, the second one had EPIORDER=03 and the last one of the same spell had EPIORDER=99, then the three episodes are treated just the same as if they were numbered 01, 02 and 03 (as most multi-episode spells are). The dataset is then split into the first and last episodes of each spell (which are often the same, as most spells comprise only one episode). Diagnosis and procedure variables are taken from the first episode (DIAG1-DIAG7, OPER1-OPER4, date of primary procedure OP_DTE_1). Outcome variables are taken from the last episode (DISMETH (method of discharge), DISDEST (destination on discharge), DISDATE). DISMETH=’4’ is used to indicate death (it does not always coincide with DISDEST=’79’ but it is used by the DH).
As hospitals merge and services reorganised, provider codes (PROCODE) may change from one HES year to the next. In order to track hospitals over time, the provider codes need to be unified, i.e. just one code needs to identify each trust throughout. To date, codes have been unified as of the trust status at October 1st 2003.
The new statistical wards and the Department of the Environment, Transport and the Regions index of multiple deprivation quintile (IMD2000) are then added to HES.
Table A. List of three digit ICD-10 codes for adverse events
ICD-10 code
Diagnosis Medical and surgical misadventures Y60 Unintentional cut, puncture, perforation or haemorrhage during surgical and medical care Y61 Foreign object accidentally left in body during surgical and medical care Y62 Failure of sterile precautions during surgical and medical care Y63 Failure in dosage during surgical and medical care Y64 Contaminated medical or biological substances Y65 Other misadventures during surgical and medical care Y66 Non-administration of surgical and medical care Y69 Unspecified misadventure during surgical and medical care Other Adverse events G97 Post procedural disorders of the nervous system, not elsewhere classified H59 Post procedural disorders of the eye and adnexa, not elsewhere classified H95 Post procedural disorders of the ear and mastoid process, not elsewhere classified I97 Post procedural disorders of the circulatory system, not elsewhere classified J95 Post procedural respiratory disorders not elsewhere classified K91 Post procedural disorders of the digestive system, not elsewhere classified M96 Post procedural musculoskeletal disorders, not elsewhere classified N99 Post procedural disorders of the genitourinary system, not elsewhere classified O08 Complications following abortion and ectopic and molar pregnancy T80 Complications following infusion, transfusion and therapeutic injection T81 Complications of procedures, not elsewhere classified T82 Complications of cardiac and vascular prosthetic devices, implants and grafts T83 Complications of genitourinary prosthetic devices, implants and grafts T84 Complications of internal orthopaedic prosthetic devices, implants and grafts T85 Complications of other internal prosthetic devices, implants and grafts T86 Failure and rejection of transplanted organs and tissues T87 Complications peculiar to reattachment and amputation T88 Other complications of surgical and medical care, not elsewhere classified Y70 Anaesthesiology devices associated with adverse incidents Y71 Cardiovascular devices associated with adverse incidents Y72 Otorhinolaryngological devices associated with adverse incidents Y73 Gastroenterology and urology devices associated with adverse incidents Y74 General hospital and personal-use devices associated with adverse incidents Y75 Neurological devices associated with adverse incidents Y76 Obstetric and gynaecological devices associated with adverse incidents Y77 Opthalmic devices associated with adverse incidents Y78 Radiological devices associated with adverse incidents Y79 Orthopaedic devices associated with adverse incidents Y80 Physical medicine devices associated with adverse incidents Y81 General- and plastic-surgical devices associated with adverse incidents Y82 Other and unspecified medical devices associated with adverse incidents Y83 Surgical operation and other surgical procedures as the cause of abnormal reaction of the patient, or of later complication, without a mention of misadventure at the time of the procedure Y84 Other medical procedures as the cause of abnormal reaction of the patient, or of later complication, without mention of misadventure at the time of the procedure
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