Glasgow Outcome Scale: research scale or blunt instrument?

[Wilson JTL] and colleagues have investigated the validity of the GOS and the relation between the two scores and subjective reports of health outcome and tests of neuropsychological function.2,3 Correlations with tests of cognition were modest (about 0.2) whereas correlations with psychiatric tests of mood such as the Beck Depression Inventory, and with health surveys, such as the General Health Questionnaire, Short-Form Health questionnaire, and the Neurobehavioural Functioning Inventory, were more promising (about 0.35-0.60). The use of the extra categories provided by the GOSE generally improved the relations only slightly with the Spearman rank correlation, a statistic that is heavily dependent on the number categories used.4 The sample of patients used was selective, being taken from neurosurgical and psychiatric outpatient clinics. The two scales were more sensitive than the Barthel Index, a similar outcome index. However, the study was based on outcome 6 months after the accident. Since 36% of the patients had severe head injury or worse according to the Glasgow Coma Scale, 6 months could be too early for assessment of outcome. Within these first 6 months many patients who have experienced such severe injury will still be recovering from the physical injuries, and few patients will have been challenged by attempts to return to work and other experiences that are likely to bring cognitive impairments to the forefront for consideration.5 The failure to find any relation with age6,7 may be another indication of a lack of sensitivity of this approach and of the sclae itself. Because of uncertainty about the different stages of recovery after brain injury and how these may depend both qualitatively and chronologically on the severity of brain injury,8 these factors must be allowed for in assessment of outcome scales.