Interrater reliability of the National Institutes of Health Stroke Scale: Rating by neurologists and nurses in a community-based stroke incidence study

The reliability of the National Institutes of Health Stroke Scale (NIHSS) for use by trained neurologists in clinical trials of acute stroke has been established in several hospital-based studies. However, it also has the potential for application in community-based settings and to be used by nonneurologists: issues which have not been explored before. Hence, we aimed to determine the reliability of the NIHSS when administered by research nurses within the existing North Eastern Melbourne Stroke Incidence Study. Using the NIHSS, thirty-one consecutively registered stroke patients were assessed by 2 neurologists and 1 of 2 trained research nurses. The interrater reliability of observations was compared using weighted and unweighted kappa statistics and intraclass correlation coefficients (ICC). There was a high level of agreement for total scores between the 2 neurologists (ICC = 0.95) and between each neurologist and research nurse (ICC = 0.92 and 0.96). While there was moderate to excellent agreement among neurologists and research nurse (weighted kappa > 0.4) for the majority of the NIHSS items, there was poor agreement for the component 'limb ataxia'. Overall, agreement between nurse and neurologist for individual items was not significantly different from agreement between neurologists. It appears that in both hospital and community settings, trained research nurses can administer the NIHSS with a reliability similar to stroke-trained neurologists. This ability could be used to advantage in large community-based trials and epidemiological studies.