Bernadette Alves

Explaining differences in English hospital death rates using routinely collected data

Objectives: To ascertain hospital inpatient mortality in England and to determine which factors best explain variation in standardised hospital death ratios. Design: Weighted linear regression analysis of routinely collected data over four years, with hospital standardised mortality ratios as the dependent variable. Setting: England. Subjects:Eight million discharges from NHS hospitals when the primary diagnosis was one of the diagnoses accounting for 80% of inpatient deaths. Main outcome measures: Hospital standardised mortality ratios and predictors of variations in these ratios. Results: The four year crude death rates varied across hospitals from 3.4% to 13.6% (average for England 8.5%), and standardised hospital mortality ratios ranged from 53 to 137 (average for England 100). The percentage of cases that were emergency admissions (60% of total hospital admissions) was the best predictor of this variation in mortality, with the ratio of hospital doctors to beds and general practitioners to head of population the next best predictors. When analyses were restricted to emergency admissions (which covered 93% of all patient deaths analysed) number of doctors per bed was the best predictor. Conclusion: Analysis of hospital episode statistics reveals wide variation in standardised hospital mortality ratios in England. The percentage of total admissions classified as emergencies is the most powerful predictor of variation in mortality. The ratios of doctors to head of population served, both in hospital and in general practice, seem to be critical determinants of standardised hospital death rates; the higher these ratios, the lower the death rates in both cases.

Hospital admissions for acute anaphylaxis: time trend study.

Anecdotal evidence suggests that the incidence of acute anaphylaxis is increasing.1 Reasons for this supposed increase are poorly understood although a number of factors associated with the “Western lifestyle” have been implicated, such as changes in diet and the increasing use of therapeutic drugs. We investigated trends in hospital admissions for acute anaphylaxis using routinely collected national hospital discharge statistics from 1991-2 to 1994-5. The hospital episode statistics database captures information on every admission to NHS hospitals in England. One primary diagnosis code and up to six secondary codes are recorded, the latter providing information on aetiology. We looked at hospital discharges occurring between 1 April 1991 and 31 March 1995 in which the primary ICD-9 (international classification of diseases, ninth revision) code was anaphylaxis (either anaphylactic shock (ICD-9 code 995.0) or anaphylactic shock due to …

Age, sex, geographical and socio-economic variations in admissions for anaphylaxis: analysis of four years of English hospital data.

Background Although the most severe of the allergic disorders, the epidemiology of anaphylaxis remains poorly described. Hospital admissions for anaphylaxis in England more than doubled during the 1990s.

Rising incidence of Kawasaki disease in England: analysis of hospital admission data.

Kawasaki disease is the leading cause of acquired heart disease in children in the developed world and may be a risk factor for adult ischaemic heart disease.1 A fifth of untreated children develop cardiac lesions during the acute phase of the disease. The cause remains uncertain. Epidemiological studies support an infectious agent inducing the disease in a genetically susceptible minority. Superantigen toxins have been implicated. Reported incidence rates differ considerably throughout the developed world with rates in Japan 10 times those in the United States and 30 times those in the United Kingdom and Australia.2–4 Hospital surveillance data suggest the incidence of Kawasaki disease in Japan has risen by over 50% between 1987 and 1998.2 To ascertain whether there had been a similar rise in England, we …

Comparison of UK paediatric cardiac surgical performance by analysis of routinely collected data 1984–96: was Bristol an outlier?

BACKGROUND Reports of high mortality after paediatric cardiac surgery at the Bristol Royal Infirmary, UK, led to the establishment of an independent public inquiry. A key question was whether or not the mortality statistics in Bristol were unusual compared with other specialist centres. To answer this question, we did a retrospective analysis of mortality in the UK using two datasets. METHODS Data from the UK Cardiac Surgical Register (CSR; January, 1984, to March, 1996) and Hospital Episode Statistics (HES; April, 1991, to December, 1995) were obtained for all 12 major centres in which paediatric cardiac surgery is done in the UK. The main outcome measure was mortality within 30 days of a cardiac surgical procedure. We estimated excess deaths in Bristol using a random-effects model derived from the remaining 11 centres. Additionally, a sensitivity analysis was done and case-mix examined. FINDINGS For children younger than 1 year, in open operations, the mortality rate in Bristol was around double that of the other centres during 1991-95: within the CSR, there were 19.0 excess deaths (95% interval 2-32) among 43 deaths; and in HES, there were 24.1 excess deaths (12-34) among 41 deaths recorded. There was no strong evidence for excess mortality in Bristol for closed operations or for open operations in children older than 1 year. INTERPRETATION Our results suggest that Bristol was an outlier, and we do not believe that statistical variation, systematic bias in data collection, case-mix, or data quality can explain a divergence in performance of this size.

Investigating the relationship between affluence and elective caesarean sections

The proportion of women delivering by caesarean section has increased dramatically in England and many westernised countries. It has been suggested that one important reason for this increase is the growing proportion of women opting for elective caesareans for lifestyle reasons, a trend that is, it is argued, most common among the affluent. We investigated the hypothesis that affluent women are more likely to deliver by elective caesarean section. Logistic regression modelling was used to analyse data from half a million women who delivered in English NHS hospitals between 1996 and 2000. We found that women living in the most affluent areas of England were significantly more likely to have an elective caesarean section than their deprived counterparts.