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Biomedical subjects

P A Sandercock

Publications and source records attributed to P A Sandercock.

42 records · Page 3Linked to original sources
PubMed1989

Incidence of transient ischemic attacks in Oxfordshire, England.

The Oxfordshire Community Stroke Project is a prospective register of all new cases of stroke and transient ischemic attack (TIA) in a population of 105,000 residents of Oxfordshire, England. Between November 1, 1981, and October 31, 1986, 184 patients presented for the first time to a general practitioner or hospital with a TIA. The crude annual incidence rate was 0.35/1000, 0.42/1000 standardized to the 1981 population of England and Wales. We estimate that each year approximately 21,000 patients in England and Wales (about half of whom are greater than 70 years old) consult a doctor for the first time with a TIA. Approximately 80% of our 184 patients had TIAs in the carotid distribution; the remainder had TIAs in the vertebrobasilar distribution or TIAs of uncertain vascular distribution. The incidence of TIA increased sharply with increasing age, and the overall incidence in men was very similar to that in women (incidence ratio 1.3). However, in middle age, men were much more likely to suffer a TIA than women (odds ratio 2.6), which probably explains the marked male predominance in most hospital-based studies and treatment trials in which the elderly, and thus women, are underrepresented. This has important implications for the design and interpretation of clinical trials of treatment for TIAs.

Adolescent↗
PubMed1986

Stroke and migraine in the Oxfordshire Community Stroke Project.

A total of 323 cases of first-ever stroke were registered in the first 2 years of the Oxfordshire Community Stroke Project. Of these patients, 244 (76%) had a stroke due to cerebral infarction. There was a past history of migraine headaches in 56 (17%) of the 323 cases of stroke and in 44 (18%) of the 244 cases of cerebral infarction. A past history of migraine headaches was no commoner in patients with stroke due to cerebral infarction than in those with stroke due to intracranial haemorrhage. One hundred and seventy-three (71%) patients with cerebral infarction had at least one risk factor for ischaemic stroke; the frequency of such risk factors was similar in patients with and without a history of migraine. In 7 (3%) of the 244 patients the cerebral infarction was presumed to be "migrainous"; however, only 3 of these 7 (1.2% of the 24) were free of risk factors for ischaemic stroke. If all 7 cases were considered migrainous, the incidence rate of first migrainous cerebral infarction was 3.36 per 100,000 per year (95% confidence limits 0.87-5.86). If only the 3 patients who were free of risk factors were included, the incidence was 1.44 per 100,000 per year (95% confidence limits 0-3.07).

Adult↗
PubMed1985

Clinical diagnosis of intracranial haemorrhage using Guy's Hospital score.

We tested the Guy's Hospital stroke diagnostic score using the clinical data from two independent samples of patients with acute stroke. These were 228 patients from the Oxfordshire community stroke project and 130 referred to the National Hospital for Nervous Diseases in London. The diagnosis was confirmed by computed tomography or necropsy in each case. The optimum cut off point on the clinical score for the differentiation of intracranial haemorrhage from infarction was found to be the same for both the patients in our study and those from whose data the score was derived originally. Set at this level, the score achieved a sensitivity for the diagnosis of haemorrhage of 81% and 88% in the patients from Oxford and London, respectively. In those from Oxford infarction was diagnosed with a sensitivity of 78% with an overall predictive accuracy of 78% with an overall London the sensitivity for infarction was also 78% with an overall predictive accuracy of 82%. When it is essential to exclude intracerebral blood before starting treatment in the small proportion of patients with stroke who require anticoagulation the Guy's Hospital score is not sufficiently accurate to replace computed tomography. The score is, however, the most accurate clinical means of differentiating haemorrhage from infarction as the cause of stroke. It is suggested that it should be used as a screening test in epidemiological studies and in large scale trials of low risk treatment for the secondary prevention of stroke when computed tomography in all cases is impracticable.

Cerebral Hemorrhage↗
PubMedDate not supplied

The miracle of DICE therapy for acute stroke: fact or fictional product of subgroup analysis?

OBJECTIVE: To determine whether inappropriate subgroup analysis together with chance could change the conclusion of a systematic review of several randomised trials of an ineffective treatment. DESIGN: 44 randomised controlled trials of DICE therapy for stroke were performed (simulated by rolling different coloured dice; two trials per investigator). Each roll of the dice yielded the outcome (death or survival) for that "patient." Publication bias was also simulated. The results were combined in a systematic review. SETTING: Edinburgh. MAIN OUTCOME MEASURE: Mortality. RESULTS: The "hypothesis generating" trial suggested that DICE therapy provided complete protection against death from acute stroke. However, analysis of all the trials suggested a reduction of only 11% (SD 11) in the odds of death. A predefined subgroup analysis by colour of dice suggested that red dice therapy increased the odds by 9% (22). If the analysis excluded red dice trials and those of poor methodological quality the odds decreased by 22% (13, 2P = 0.09). Analysis of "published" trials showed a decrease of 23% (13, 2P = 0.07) while analysis of only those in which the trialist had become familiar with the intervention showed a decrease of 39% (17, 2P = 0.02). CONCLUSION: The early benefits of DICE therapy were not confirmed by subsequent trials. A plausible (but inappropriate) subset analysis of the effects of treatment led to the qualitatively different conclusion that DICE therapy reduced mortality, whereas in truth it was ineffective. Chance influences the outcome of clinical trials and systematic reviews of trials much more than many investigators realise, and its effects may lead to incorrect conclusions about the benefits of treatment.

Bias↗
PubMedDate not supplied

Acute stroke treatment in UK hospitals: the Stroke Association survey of consultant opinion.

The aim of the Stroke Association survey was to document United Kingdom consultant opinion of the immediate treatment for patients with acute stroke. A national postal survey of all UK hospital consultant general physicians, geriatricians and neurologist was carried out in 1992/3. We identified 1,953 consultants who routinely cared for patients with acute stroke; 39% of them regularly used aspirin for patients with acute stroke and 10% used low-dose subcutaneous heparin. Other treatments were rarely used. There was much uncertainty about the effectiveness of all currently available acute stroke treatments; 73% of physicians were prepared to start aspirin before a CT scan, but a much smaller proportion would start heparin therapy without one. Twenty-seven percent of consultants would actively treat hypertension in the initial 24 hours after stroke. Routine aspirin for secondary prevention after ischaemic stroke was widely accepted, but blood cholesterol lowering by drugs was not. In conclusion, aspirin and heparin alone are the only routinely used treatments for the immediate treatment of acute stroke; other treatments are used sparingly or not at all. The great uncertainty about the value of all available acute stroke treatments should encourage participation in randomised controlled trials.

Aspirin↗