Variations between countries in outcome after stroke in the International Stroke Trial (IST)

• Published in: Stroke (1970) Vol. 32; no. 6; pp. 1370 - 1377
• Main Authors: WEIR, N. U, SANDERCOCK, P. A. G, LEWIS, S. C, SIGNORINI, D. F, WARLOW, C. P
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01.06.2001; American Heart Association, Inc
• Subjects: Aged; Argentina - epidemiology; Aspirin - therapeutic use; Australia - epidemiology; Biological and medical sciences; Europe - epidemiology; Female; Follow-Up Studies; Heparin - therapeutic use; Humans; Logistic Models; Male; Medical sciences; Models, Statistical; Neurology; Outcome Assessment (Health Care) - statistics & numerical data; Outcome Assessment (Health Care) - trends; Poland - epidemiology; Predictive Value of Tests; Process Assessment (Health Care) - statistics & numerical data; Process Assessment (Health Care) - trends; Prognosis; Quality of Health Care; Randomized Controlled Trials as Topic - statistics & numerical data; ROC Curve; Severity of Illness Index; Stroke - diagnosis; Stroke - drug therapy; Stroke - mortality; Survival Rate - trends; United Kingdom - epidemiology; Vascular diseases and vascular malformations of the nervous system; Handicap; Human; Nervous system diseases; Stroke; Prognosis; Mortality; Cardiovascular disease; Cerebral disorder; Vascular disease; Disability; Geographic distribution; Central nervous system disease; Cerebrovascular disease; Comparative study; Geographical variation
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/01.STR.32.6.1370

This study describes the large variations in outcome after stroke between countries that participated in the International Stroke Trial and seeks to define whether they could be explained by variations in case mix or by other factors. We analyzed data from the 15 116 patients recruited in Argentina, Australia, Italy, the Netherlands, Norway, Poland, Sweden, Switzerland, and the United Kingdom: We compared crude case fatality and the proportion of patients dead or dependent at 6 months; we used logistic regression to adjust for age, sex, atrial fibrillation, systolic blood pressure, level of consciousness, and number of neurological deficits. We used the frequency of prerandomization head CT scan and prescription of aspirin at discharge to indicate quality of care. The differences in outcome (all treatment groups combined) between the "best" and "worst" countries were very large for death (171 cases per 1000 patients) and for death or dependency (375 cases per 1000 patients). The differences were somewhat smaller after adjustment for case mix (160 and 311 cases per 1000 patients, respectively). Process of care may have accounted for some but not all of the residual variation in outcome. Adjustment for case mix explained only some of the variation in outcome between countries. The residual differences in outcome were too large to be explained by variations in care and most likely reflect differences in unmeasured baseline factors. These findings demonstrate the need to achieve balance of treatment and control within each country in multinational randomized controlled stroke trials and the need for caution in the interpretation of nonrandomized comparisons of outcome after stroke between countries.