Material and method
All patients from Asker and Bærum who were hospitalised with acute stroke in 1994 or 1995 were included in the register. Bærum hospital had two separate stroke units; one ward for patients with recent strokes and one for training and rehabilitation of stroke patients. In 1995, the two municipalities (Asker and Bærum) had a population of 158 131. The stroke unit was part of the medical department and was under professional leadership by specialists in internal medicine and geriatrics. Organisation of the unit was based on cross-disciplinary cooperation with groups of physicians, nurses, assistant nurses, physiotherapists, occupational therapists, speech therapists and social workers worked working closely together on acute treatment and rehabilitation. If cerebral infarction occurred, a neurosurgeon was routinely contacted and consulted. Most patients in the register were treated in the stroke unit. When there were too many patients in the unit; some were occasionally placed in a ward for internal medicine.
Information was recorded for all patients who were hospitalised with stroke (ICD-9-code 431 - 436) as a main diagnosis or a subdiagnosis. 9ICD-9-codes comprise cerebral infarction, cerebral embolism, cerebral haemorrhage, subarachnoidal bleeding and subdural bleeding, but not epidural haematoma. 457 patients were identified, and of these the 421 who were living in Asker or Bærum were included in the register.
We recorded information on previous strokes and transitory ischemic attacks and risk factors for cerebral disease such as hypertension, symptom-giving arteriosclerosis (claudicatio intermittens, coronary disease and carotis stenosis), daily smoking, diabetes and atrial fibrillation. Clinical symptoms and neurological events were recorded according to a classification used by Oxfordshire Community Stroke Project (OCSP), where stroke is divided into four different syndromes based on localisation and extent (11) - (13).
The four stroke syndromes are:
POCS (posterior circulation syndrome) - posterior circulatory syndrome
LACS (lacunar circulation syndrome)
TACS (total anterior circulation syndrome
PACS (partial anterior circulation syndrome)
As a diagnostic tool, we used an algorithm requiring the examining physician to record whether the neurological event was one-sided, if applicable which side it was on and whether the localisation was related to face, arm/hand, nystagmus or dizziness. These results were treated and classified according to the OCSP-classification.
Blood pressure was recorded upon arrival and the first blood pressure was measured the day after arrival and at discharge. Values were recorded for Hb, leucocytes, trombocytes, glucose, sodium, potassium and CRP taken within two hours after hospitalisation. Medicines and the patients’ level of consciousness were recorded at arrival. Patients with a level of consciousness below 11 (according to the Glasgow coma scale [GSC]) were classified as somnolent and patients with a score lower than seven were classified as comatous. Previously diagnosed dementia was recorded. The results of previously taken, more recent or repeated CT caput examinations were also recorded. Depending on the outcome the following was recorded; the duration of the stay, hospital morbidity and medication upon arrival and discharge. Level of functioning at discharge was related to everyday activities and assessed through a cross-disciplinary integrated approach by a physician, a nurse, a physiotherapist and an occupational therapist. In addition to tests such as Scandinavian Stroke Score, Barthel Index and Minimal Mental Status (MMS), the assessment especially emphasised the patient’s ability to master daily activities at home.
Information on survival and mortality was retrieved from national population statistics (Statistics Norway) in January 2003. The prevalence of recurrent stroke after the primary stroke that led to inclusion in the register was followed up through January 2003 by review of diagnosis lists (from 1.1.1994 up to 1.1.1995) in the hospital’s database.
Survival is presented by a Kaplan/Meier plot. The difference between groups was analysed with a Cox Proportional Hazard model. A two-sided p-value < 0.05 was considered significant. Fischer’s exact test was used to compare outcomes for the two subgroups stroke and myocardial infarction.