Classification of Cause of Death After Stroke in Clinical Research

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Abstract
Classification of outcome events is essential in clinical research. The Executive Committee of the European/Australasian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT), a secondary prevention trial in patients with cerebral ischemia, repeatedly encountered problems in classifying the cause of death after a stroke if the interval between these events was relatively long. We aimed to develop guidelines for classifying such events. Twenty-nine neurologists with a special interest in stroke filled out a questionnaire and audited 5 case vignettes. On the basis of this information, we developed a proposal for classifying causes of death after stroke. This proposal was evaluated in an interobserver analysis in which 10 neurologists or residents in neurology assessed 20 of 100 case vignettes. Initially, there was great variation in classifications of the case vignettes, mainly because the correspondents strongly disagreed about the relative importance of the interval between stroke and death, the degree of disability after stroke, the discharge destination (home or institutional care), and the coexistence of infection. In the new proposal, the main criteria were "interval after stroke" (cutoff point at 1 month) and "best Rankin grade after stroke" (cutoff at 3). In the interobserver analysis, good agreement was obtained among the 5 pairs of neurologists who assessed the 20 case vignettes (kappa 0.80 95% CI, 0.68 to 0.92). In the absence of guidelines, neurologists show striking variation in the classification of causes of death in patients who die after a stroke. With precise rules, agreement in the classification of death after stroke strongly improved.