M P Vessey

A prospective study of acute cerebrovascular disease in a community of about 105,000 people is reported. The study protocol combined rapid clinical assessment of patients with accurate diagnosis of the pathological type of stroke by CT or necropsy, whether or not they were admitted to hospital. The study population was defined as those people who were registered with one of 50 collaborating general practitioners (GPs). Referrals to the study were primarily from the GPs though, to ensure complete case ascertainment, hospital casualty and admission registers, death certificates and special data from the Oxford Record Linkage Study were also scrutinized. Six hundred and seventy five cases of clinically definite first-ever in a lifetime stroke were registered in four years yielding a crude annual incidence of 1.60/1,000 or 2.00/1,000 when adjusted to the 1981 population of England and Wales. The age and sex specific incidence rates for first stroke showed a steep rise with age for both sexes. The odds of a male sustaining a first stroke were 26% greater than those of a female. Ninety one per cent of patients were examined in a median time of four days after the event by a study neurologist and 88% had cerebral CT or necropsy.

OBJECTIVES: To compare outcome between intensive care units in Britain and Ireland both before and after adjustment for case mix with the American APACHE II method and to validate the American APACHE II method in Britain and Ireland. DESIGN: Prospective, cohort study of consecutive admissions to intensive care units. SETTING: 26 general intensive care units in Britain and Ireland. SUBJECTS: 8796 admissions to the study intensive care units. MAIN OUTCOME MEASURE: Death or survival at discharge from intensive care unit and hospital. RESULTS: At discharge from both intensive care unit and hospital there was a greater than twofold variation in crude mortality between the 26 units. After adjustment for case mix, variations in mortality were still apparent. For four intensive care units the observed numbers of deaths were significantly different from the number predicted by the American APACHE II equation. The overall goodness of fit, or predictive ability, of the APACHE II equation for the British and Irish data was good, being only slightly inferior to that obtained when the equation was tested on the data from which it had been derived. When patients were grouped by various factors such as age and diagnosis, the equation did not adjust across the subgroups in a uniform manner. CONCLUSIONS: The American APACHE II equation did not fit the British and Irish data. Use of the American equation could be of advantage or disadvantage to individual intensive care units, depending on the mix of patients treated.

OBJECTIVES: To describe the extent of variation in the case mix of adult admissions to general intensive care units in Britain and Ireland and investigate the impact of such variation on outcome. DESIGN: Prospective, cohort study of consecutive admissions to intensive care units. SETTING: 26 general intensive care units in Britain and Ireland. SUBJECTS: 9099 admissions to the intensive care units studied. MAIN OUTCOME MEASURE: Death or survival at discharge before and after adjustment of case mix (age, history of chronic conditions, surgical status, diagnosis, and severity of illness) according to the APACHE II method. RESULTS: Important differences in case mix were found, with large variations between the units. Hospital mortality was significantly associated with most of the case mix factors investigated. CONCLUSIONS: Comparing crude death rates in hospital between intensive care units may be misleading indicators of performance. The collection of data on case mix needs to be standardised and differences in case mix adjusted for when comparing outcome between different intensive care units.