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In-hospital deaths as fraction of all deaths within 30 days of hospital admission for surgery: analysis of routine statistics Michael J Goldacre, Myfanwy Griffith, Leicester Gill, Anne Mackintosh

been missed by analysis of in-hospital mortality alone. The percentage of deaths that occurred after discharge or transfer increased substantially in the later years covered by the study.

Comment The percentage of deaths within 30 days of an admission for surgery that are in-hospital deaths has fallen substantially since routine hospital statistics were first collected in the 1960s and 1970s. This reflects decreases in length of hospital stays and an increase in the transfer of acutely ill patients between hospitals for specialist care. In-hospital mortality alone is now an

No of deaths

Death rates after surgical care are increasingly analysed to estimate prognosis and for clinical audit and quality assessment. Expectations are growing among health professionals and the public that hospitals will know about, and learn from, the death rates of their patients. However, routine statistics commonly provide information only on deaths that occur during the hospital admission in which surgery was done. Rates based on these deaths are conventionally known as in-hospital death rates and are typically analysed as those that occur within 30 days after admission or surgery. Systems of national hospital statistics in England were designed in the 1960s and redesigned in the mid1980s.1 2 Hospital statistics are not linked to death certificate data nationally, although this has long been feasible.3 4 Even the National Confidential Enquiry into Perioperative Deaths, a meticulous ongoing national study with local clinical reporting and case note review of deaths, is constrained practically to the identification of deaths in the hospital admissions in which the operations were done.5 By using hospital data linked to death certificate data, we studied the extent to which in-hospital deaths accounted for all deaths within 30 days of hospital admissions during which operations were done.

BMJ 2002;324:1069–70

1963-74 Index admission

300

Other admissions

250

150 100 50

bmj.com

No of deaths

0 800

1975-86

700 600 500 400 300 200 100 0

No of deaths

We used anonymised statistical abstracts of hospital records that were linked to data from death certificates in the former Oxford health region from 1963 to 1998. Data collection covered a population of 300 000 from 1963 to 1965, 850 000 from 1966 to 1974, 1.9 million from 1975 to 1986, and 2.5 million from 1987. We identified all deaths within 30 days of an admission for surgery. Ideally, we would have related deaths to days from an operation but dates of surgery were incompletely recorded. We tabulated deaths at single day intervals between admission and death and present results for three periods: 1963-74, 1975-86, and 1987-98. More detailed analysis of successive years within 1987-98 showed that the pattern of death for individual years was similar to that in the whole period. Deaths were classified by place of occurrence: in hospital in the same admission as the operation, in hospital after readmission, after transfer to a different hospital, or outside hospital. During 1963-98, 41 200 people died within 30 days after an admission in which they had surgery. Deaths in the admission in which surgery occurred (in-hospital deaths) represented 79.3% of all deaths within 30 days in 1963-74 (3552/4482), 71.2% in 1974-86 (8710/ 12 239), and 61.2% in 1987-98 (14 977/24 479). Most deaths that occurred within a few days of surgery were in-hospital deaths (figure). With increasing time from admission, increasing numbers of deaths within 30 days occurred elsewhere and would have 4 MAY 2002

continued over

200

Methods and results

BMJ VOLUME 324

350

Unit of Health-Care Epidemiology, Department of Public Health, University of Oxford, Oxford OX3 7LF Michael J Goldacre director Myfanwy Griffith computer programmer Leicester Gill computer scientist Anne Mackintosh research officer

1400

1987-98

1200 1000 800 600 400 200 0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Days after admission

Days from admission to death within 30 days of admission 1963-98, subdividing deaths into those during hospital admission for surgery and those occurring elsewhere

1069

Papers Correspondence to: M J Goldacre michael.goldacre@ dphpc.ox.ac.uk

incomplete measure of mortality even within 30 days of care. To identify the missing deaths, hospital statistical records need to be linked to data from death certificates. This is now feasible nationally in England.

Competing interests: None declared. 1 2

Contributors: MJG designed the study and wrote the first draft of the paper. LG and MG built the linked files. MG and AM analysed the data. All authors contributed to later drafts of the paper. MJG and MG are the guarantors. Funding: AM is funded by the Department of Health as part of its funding of the National Centre for Health Outcomes Development. The views expressed in this paper are those of the authors and not necessarily those of the Department of Health. The Unit of Health-Care Epidemiology is funded by the South East Regional Office of the NHS Executive.

3 4

5

Department of Health and Social Security. Hospital activity analysis. London: DHSS, 1969. Steering Group on Health Services Information. First report to the secretary of state. London: HMSO, 1982. Acheson ED. Medical record linkage. Oxford: Oxford University Press, 1967. Henderson J, Goldacre MJ, Simmons H, Griffith M. Recording of deaths in hospital information systems: implications for audit and outcome studies. J Epidemiol Community Health 1992;42:297-9. Callum KG, Gray AJG, Hoile RW, Ingram GS, Martin IC, Sherry KM, et al. Then and now. The 2000 report of the National Confidential Enquiry into Perioperative Deaths. London: National CEPOD, 2000.

(Accepted 15 October 2001)

Preventing deaths by drowning in children in the United Kingdom: have we made progress in 10 years? Population based incidence study Jo R Sibert, Ronan A Lyons, Beverley A Smith, Peter Cornall, Valerie Sumner, Maxine A Craven, Alison M Kemp, on behalf of the Safe Water Information Monitor Collaboration

Editorial by Brenner

Departments of Child Health and Epidemiology Statistics and Public Health, Collaboration for Accident Prevention and Injury Control, University of Wales College of Medicine, Llandough Hospital, Penarth CF64 2XX Jo R Sibert professor of community child health Ronan A Lyons professor of public health Beverley A Smith research nurse Alison M Kemp senior lecturer Royal Society for Prevention of Accidents, Birmingham B5 7ST Peter Cornall head of water and leisure Maxine A Craven research manager continued over

Detailed information on drowning in children is not routinely collected by offices of national statistics. Few studies have been carried out in the United Kingdom, and none has been done on British children abroad. In 1988-9, two of the authors (AMK and JRS) combined information from national statistical offices, police forces (Royal Life Saving Society), and from a press cutting service (Royal Society for Prevention of Accidents) for a detailed analysis of deaths by drowning in children.1–3 This analysis found that 149 children had drowned in the United Kingdom during 1998-9. It also identified a safety agenda, which focused on young children in garden ponds and pools and on older children swimming without supervision. Over the past 10 years there have been initiatives on children’s safety in water, particularly swimming. We obtained similar information for 1998-9 to identify changes that have occurred in 10 years and assessed whether these initiatives on safety have been successful.

Deaths by drowning in children aged 0-14 years were identified in the same way in 1988-9 and 1998-9. We compared numbers of cases of drowning in the two periods by calculating the observed and expected numbers and comparing them with the expected numbers taken from the observed numbers in 1988, adjusted for the 6% increase in the child population over the 10 year period (table). We used the statistical package Confidence Interval Analysis to calculate ratios and 95% confidence intervals. We identified deaths by drowning that occurred outside the United Kingdom from the Royal Society for Prevention of Accidents’ survey of press cuttings. A total of 104 children drowned in the United Kingdom in 1998-9 compared with 149 in 1988-9; this represents a significant fall in incidence. The numbers of children drowning fell in all sites, apart from deaths in garden ponds, where the numbers rose significantly (P < 0.05). The decreases in drownings in three areas

Drownings in children aged 0-14 years in the United Kingdom 1998-9

1988-9 Observed

Expected

Bath

25

23.58

25

Garden pond

11

10.37

21

2.03 (1.25 to 3.10)*

Domestic pool

18

16.97

4

0.24 (0.06 to 0.60)* 0.66 (0.21 to 1.55)

Location of drownings

Private pool River, canal, lake

BMJ 2002;324:1070–1

Methods and results

Public pool Sea

Observed

Ratio (95% CI) 1.06 (0.69 to 1.57)

8

7.54

5

56

52.81

31

0.59 (0.40 to 0.83)*

2

1.89

2

1.06 (0.13 to 3.82)

20

18.70

10

0.53 (0.26 to 0.98)*

Other

9

8.41

6

0.71 (0.26 to 1.55)

Total

149†

140.51

104‡

0.74 (0.61 to 0.90)*

*P