Adrian Cook

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.

Allergen and dust exposure as determinants of work-related symptoms and sensitization in a cohort of flour-exposed workers; a case–control analysis

OBJECTIVES To estimate the incidence of specific IgE sensitization and allergic respiratory symptoms among UK bakery and flour mill workers; and to examine the roles of flour aeroallergen and total dust exposures in determining these outcomes. METHODS A cohort of 300 new employees, without previous occupational exposure to flour, were followed prospectively for a median (range) of 40 (1-91) months. Cases-defined as those developing work-related symptoms or a positive skin prick test to flour or alpha-amylase during follow up--were compared with controls, matched for duration of employment. Exposures to flour aeroallergen and total inhalable dust were estimated using a questionnaire and personal sampling techniques. RESULTS Incidence rates for work-related eye/nose and chest symptoms were 11.8 and 4.1 cases per 100 person years (py), respectively. Fewer employees developed positive skin prick tests to flour (2.2 cases per 100 py) or alpha-amylase (2.5 cases per 100 py). Positive skin tests to occupational allergens were more common among those with new work-related symptoms. There were clear relationships between the risks of developing work-related symptoms or a positive skin prick test and three categories of estimated exposure to total dust or flour aeroallergen. Atopic employees were more likely to develop a positive skin prick test-but not work-related symptoms. These findings were unaffected by age, sex or cigarette smoking. CONCLUSIONS In this population, many work-related symptoms which develop after first employment in modern UK bakeries or flour mills were not accompanied by evidence of IgE sensitization to flour or alpha-amylase. Although average dust exposures were within current occupational standards, the risks of development of upper and lower respiratory symptoms and of specific sensitization were clearly related to total dust and/or flour aeroallergen exposure. The incidence of work-related chest symptoms in the presence of a positive skin test to flour or alpha-amylase in this setting was approximately 1 case per 100 py.

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.

The problem of accuracy in dietary surveys. Analysis of the over 65 UK National Diet and Nutrition Survey

STUDY OBJECTIVE To investigate the prevalence and nature of low energy reporting in a dietary survey of British adults over 65 years of age. DESIGN Randomly selected cross sectional sample of 2060 British adults over 65 years. Four day weighed food diaries and questionnaires on health, lifestyle and socioeconomic characteristics. SETTING Great Britain. PARTICIPANTS 539 women and 558 men over 65 years who were free living and completed four day food diaries. MAIN RESULTS A high proportion of men and women were classified as low energy reporters (LERs). Reported consumption of full fat dairy products, sugar and sweet foods, and alcoholic drinks differed most between LERs and non-LERs. Among LERs, reported protein and starch intakes were higher, fat, sugar and alcohol intakes were lower. LERs of either sex were more likely to be obese, male LERs were also more likely to belong to the manual social classes. CONCLUSIONS The high level of low energy reporting probably resulted from a coalescence of factors such as the weighed diary methodology and a reluctance to report consumption of unhealthy foods. The use of validatory biomarkers such as doubly labelled water needs to be more widespread.

Trends in serious head injuries among cyclists in England: analysis of routinely collected data

As the health and environmental benefits of cycling have become better appreciated, successive governments in the United Kingdom have encouraged cycle use. Cyclists, however, face considerable risk of injury, of which head injuries most commonly result in serious adverse outcomes. Despite evidence from case-control and time trend studies, 1 2 questions remain about the effectiveness of helmets, particularly for adults. We examined trends in emergency admissions for cycle injuries to English hospitals between 1991 and 1995, during which time the wearing of helmets increased (Research International Ltd, personal communication).3 All data on admissions to NHS hospitals are entered into the hospital episode statistics database. We studied the data for the period 1 April 1991 to 31 March 1995, at which time diagnoses were classified according to ICD-9 (international classification of diseases, ninth revision), and extracted all records concerning cyclists, whether …

Reduction of exposure to laboratory animal allergens in the workplace

Objectives Evidence is now accumulating that the prevalence of allergy to laboratory animals is related to the intensity of exposure to animal allergens. Whilst airborne animal allergen concentrations may be influenced by the litter type, cage design and stock density, the effectiveness of methods to reduce personal exposure has not been objectively assessed. Methods Air samples were collected at 2 L/min and 180L/min onto polytetrafluoroethylene (PTFE) filters and the rat urinary aeroallergen (RUA) and mouse urinary aeroallergen (MUA) concentrations were measured by radioallergosorbent test (RAST) inhibition.

Measurement of exposure to mouse urinary proteins in an epidemiological study.

OBJECTIVES: To develop an assay to measure airborne mouse urinary protein (MUP) and to assess the occupational exposure to MUP in the workforce of three establishments as part of an epidemiological study examining the influence of aeroallergen exposure on the development of allergic respiratory disease. METHODS: Personal air samples were collected from nine exposure groups during a workshift. A sensitive and reproducible competitive inhibition assay, which used rabbit antisera specific for MUP, was developed and used to measure the occupational exposure to MUP. RESULTS: The personal measurements of MUP showed that people with direct contact with mice (animal technicians) had the highest exposure followed in decreasing order by those working with anaesthetised animals or their tissue (postmortem workers and scientists) and those with indirect contact with mice (supervisors, office workers, and slide production workers). The only difference in concentrations of MUP between the three establishments were found for cage cleaners, which reflected differences in working practises for this exposure category. Air samples collected during the performance of specific tasks showed that high exposures to MUP were associated with handling mice, indirect contact with mice, and washing floors. CONCLUSIONS: Exposure to mouse urinary proteins has been measured in the occupational environment. This information can be used to determine the relation between exposure to MUP and the development of allergic and respiratory disease.

Erectile dysfunction: NHS should meet current need before preventing future medical needs

EDITOR—In 1998, coincident with a shift in treatment of erectile dysfunction from specialists to general practitioners, rationing of all drug treatments for impotence was introduced in the British NHS.1 In addition to rationing by selecting 12 causes of erectile dysfunction eligible for NHS treatment (and patients with “severe distress” confirmed by a psychiatrist), the Department of Health used data on the frequency of heterosexual sexual intercourse2 to recommend that one treatment a week was appropriate for most patients. …

Evidence based policy for promoting cycle use in Britain.

Editor—We warmly welcome the Chancellor of the Exchequers pre-budget announcement that value added tax (VAT) is to be removed from cycle helmet sales.1 The decision, taken to “encourage road safety,” is supported by growing evidence of the protection offered by helmets against serious head injury.2,3 This is a small step, but a step that is certainly in the right direction. But much more could and should be done. Evidence that regular cycling benefits health is beyond doubt, substantially improving fitness and lowering the risk of heart disease.4 The exemption of bicycle helmets from VAT aims “to encourage cycle use,” yet it sits alongside a raft of proposals that will do little to curb the use of cars. Improvements in air quality from cleaner fuels will clearly benefit cyclists but will not reduce the volume of traffic. Measures that would genuinely encourage cycle use are a reduction in traffic volume, more dedicated cycle lanes, greater traffic calming   —   and what about removing VAT from bicycles? For a substantive evidence based policy bicycles need to be taken seriously; cycling must come back into the mainstream, and cyclists must not be pushed literally and metaphorically into the kerb.