Using patient­identifiable data for observational research and audit

Across the world rapid changes in the law, technology, and society are reshaping the way identifiable information about patients is handled. In Britain, doctors' longstanding common law duty of confidentiality to their patients has been supplemented by restrictions on processing electronic and paper based records in the Data Protection Act 1998, which came into force on 1 March 2000. This month the United Kingdom's Medical Research Coun­ cil (MRC) is the latest of several professional organisa­ tions to respond to these developments by updating its guidance on confidentiality and the use of personal information (see table on BMJ 's website).1–4 The MRC has provided invaluable, balanced guidance but there is still a real risk that strict and selective application of the other directives could jeopardise audit, clinical govern­ ance, and observational epidemiological research. This would compromise patient care and the public interest

Prevalence of adults with brain arteriovenous malformations: a community based study in Scotland using capture-recapture analysis

Objective: To conduct a population based study of brain arteriovenous malformation (AVM) prevalence. Methods: Multiple, overlapping sources of case ascertainment were used to establish the point prevalence of brain AVMs in the adult population of the Lothian health board of Scotland. Patients were sought retrospectively from all local general (family) practitioners, neurologists, neurosurgeons, stroke physicians, the specialist AVM clinic at the regional neuroscience centre, and routine coding of hospital discharge data. Case notes, brain imaging, and pathology reports were reviewed to validate each patient’s diagnosis and to ensure that each was alive, over the age of 16 years, and resident in the geographical area of the study on the prevalence date of 30 June 1998. Results: Of 148 potentially eligible people, 93 adults met the inclusion criteria. There were 40 women and 53 men. Men were significantly younger than women on the prevalence date (median age 39 years v 51 years, p = 0.003). Of those included, 25 (27%) had radiological evidence of prior therapeutic obliteration of their brain AVM and 9 (10%) had coexisting aneurysms. The minimum crude brain AVM prevalence was 15 per 100 000 adults and capture-recapture analysis gave an ascertainment adjusted prevalence of 18 (95% confidence interval 16 to 24) per 100 000 adults. Conclusions: The minimum estimate of brain AVM prevalence helps to assess its burden and comparative epidemiology and stresses the importance of brain AVMs as a cause of long term disability in adults

GALA: an international multicentre randomised trial comparing general anaesthesia versus local anaesthesia for carotid surgery

Background: Patients who have severe narrowing at or near the origin of the internal carotid artery as a result of atherosclerosis have a high risk of ischaemic stroke ipsilateral to the arterial lesion. Previous trials have shown that carotid endarterectomy improves long-term outcomes, particularly when performed soon after a prior transient ischaemic attack or mild ischaemic stroke. However, complications may occur during or soon after surgery, the most serious of which is stroke, which can be fatal. It has been suggested that performing the operation under local anaesthesia, rather than general anaesthesia, may be safer. Therefore, a prospective, randomised trial of local versus general anaesthesia for carotid endarterectomy was proposed to determine whether type of anaesthesia influences peri-operative morbidity and mortality, quality of life and longer term outcome in terms of stroke-free survival. Methods/design: A two-arm, parallel group, multicentre randomised controlled trial with a recruitment target of 5000 patients. For entry into the study, in the opinion of the responsible clinician, the patient requiring an endarterectomy must be suitable for either local or general anaesthesia, and have no clear indication for either type. All patients with symptomatic or asymptomatic internal carotid stenosis for whom open surgery is advised are eligible. There is no upper age limit. Exclusion criteria are: no informed consent; definite preference for local or general anaesthetic by the clinician or patient; patient unlikely to be able to co-operate with awake testing during local anaesthesia; patient requiring simultaneous bilateral carotid endarterectomy; carotid endarterectomy combined with another operation such as coronary bypass surgery; and, the patient has been randomised into the trial previously. Patients are randomised to local or general anaesthesia by the central trial office. The primary outcome is the proportion of patients alive, stroke free ( including retinal infarction) and without myocardial infarction 30 days post-surgery. Secondary outcomes include the proportion of patients alive and stroke free at one year; health related quality of life at 30 days; surgical adverse events, re-operation and re-admission rates; the relative cost of the two methods of anaesthesia; length of stay and intensive and high dependency bed occupancy

Outcome after conservative management or intervention for unruptured brain arteriovenous malformations

Neurosurger

Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials.

BACKGROUND: High-dose aspirin (≥500 mg daily) reduces long-term incidence of colorectal cancer, but adverse effects might limit its potential for long-term prevention. The long-term effectiveness of lower doses (75-300 mg daily) is unknown. We assessed the effects of aspirin on incidence and mortality due to colorectal cancer in relation to dose, duration of treatment, and site of tumour. METHODS: We followed up four randomised trials of aspirin versus control in primary (Thrombosis Prevention Trial, British Doctors Aspirin Trial) and secondary (Swedish Aspirin Low Dose Trial, UK-TIA Aspirin Trial) prevention of vascular events and one trial of different doses of aspirin (Dutch TIA Aspirin Trial) and established the effect of aspirin on risk of colorectal cancer over 20 years during and after the trials by analysis of pooled individual patient data. RESULTS: In the four trials of aspirin versus control (mean duration of scheduled treatment 6·0 years), 391 (2·8%) of 14 033 patients had colorectal cancer during a median follow-up of 18·3 years. Allocation to aspirin reduced the 20-year risk of colon cancer (incidence hazard ratio [HR] 0·76, 0·60-0·96, p=0·02; mortality HR 0·65, 0·48-0·88, p=0·005), but not rectal cancer (0·90, 0·63-1·30, p=0·58; 0·80, 0·50-1·28, p=0·35). Where subsite data were available, aspirin reduced risk of cancer of the proximal colon (0·45, 0·28-0·74, p=0·001; 0·34, 0·18-0·66, p=0·001), but not the distal colon (1·10, 0·73-1·64, p=0·66; 1·21, 0·66-2·24, p=0·54; for incidence difference p=0·04, for mortality difference p=0·01). However, benefit increased with scheduled duration of treatment, such that allocation to aspirin of 5 years or longer reduced risk of proximal colon cancer by about 70% (0·35, 0·20-0·63; 0·24, 0·11-0·52; both p<0·0001) and also reduced risk of rectal cancer (0·58, 0·36-0·92, p=0·02; 0·47, 0·26-0·87, p=0·01). There was no increase in benefit at doses of aspirin greater than 75 mg daily, with an absolute reduction of 1·76% (0·61-2·91; p=0·001) in 20-year risk of any fatal colorectal cancer after 5-years scheduled treatment with 75-300 mg daily. However, risk of fatal colorectal cancer was higher on 30 mg versus 283 mg daily on long-term follow-up of the Dutch TIA trial (odds ratio 2·02, 0·70-6·05, p=0·15). INTERPRETATION: Aspirin taken for several years at doses of at least 75 mg daily reduced long-term incidence and mortality due to colorectal cancer. Benefit was greatest for cancers of the proximal colon, which are not otherwise prevented effectively by screening with sigmoidoscopy or colonoscopy. FUNDING: None

The epidemiology of brain arteriovenous malformations in adults

Arteriovenous malformations (AVMs) of the brain are part of the spectrum of intracranial vascular malformations (IVMs). They are the leading cause of intracerebral haemorrhage in young adults, they account for ~10% of non-traumatic subarachnoid haemorrhage, and they also cause epilepsy. Not only are affected individuals subject to the initial consequences of these events, but there are substantial risks of recurrent haemorrhage and epilepsy, and long-term disability. For a disorder discovered as long ago as the mid-nineteenth century, surprisingly little is known about it. In this thesis, I begin by systematically reviewing the sizeable medical literature about brain AVM frequency, presentation, clinical course and prognosis. I did not find a single prospective, truly population-based study, which is why I set up the Scottish Intracranial Vascular Malformation Study (SIVMS) with the multidisciplinary collaboration of the four clinical neuroscience centres in Scotland. SIVMS aspires to meet the standards of the ideal study of frequency and prognosis, by using multiple, overlapping sources of case ascertainment to prospectively recruit a population based inception cohort of adults, with explicit diagnostic criteria and outcome definitions for events which are validated by independent review. During 1999-2000, 96 adults (of whom 92 were definite) were detected with a first-in-a-lifetime diagnosis of a brain AVM in Scotland. Quality of baseline demographic, clinical and basic morphological data was excellent, although detailed variables about angioarchitecture were less complete, partly because only three-quarters of patients underwent catheter angiography. The cohort was distributed in proportion to the dispersion of the Scottish population, and standardised incidence ratios were not significantly different between healthboards. The sensitivity of ICD-10 coding of brain AVMs in hospital discharge data was 72% (95%CI 61% to 80%), and its positive predictive value was 46% (95%CI 38% to 55%). Reliance on hospital discharge data for case ascertainment or a requirement for catheter angiography to make the diagnosis would have biased the cohort. Furthermore, I found that expert neuroradiologists’ assessment of AVM angioarchitecture on catheter angiography was characterised by greater intra-observer than inter-observer agreement (which ranged from less than chance for e.g. ‘angiogenesis’ to almost perfect for e.g. nidus size). In a survey with multiple, overlapping sources of ascertainment confined to the Lothian healthboard region of Scotland, using capture-recapture analysis, I found the point prevalence of brain AVMs to be 18 (95%CI 16 to 24) per 100,000 adults. In SIVMS, the crude incidence of brain AVMs in Scotland in 1999 and 2000 was 1.1 (95%CI 0.9 to 1.4) per 100,000 adults per year. Of the incident adults, 53% were male and their median age at presentation was 45 years (range 16 to 81); one fifth were incidental discoveries and four fifths were symptomatic (presentation was with intracranial haemorrhage in 59%, one or more seizure(s) in 34%, and focal neurological deficits in 7%). 9% of cases were pure arteriovenous fistulae, 75% were lobar in location, 53% were superficial, and 22% had associated aneurysms. There appeared to be significant differences between SIVMS and well-established hospital-based cohorts. Having established brain AVM prevalence, incidence and the characteristics of presenting adults, the next stage for this work is to describe prognosis for this enlarging population-based cohort. The data are being collected, the hurdles of ethical approval have been negotiated, although the direction in which privacy legislation and confidentiality guidance are heading will make this a challenging task.EThOS - Electronic Theses Online ServiceGBUnited Kingdo