A subarachnoid haemorrhage-specific outcome tool

Abstract

Functional outcome after subarachnoid haemorrhage (SAH) has traditionally been assessed using scales developed for other neurological conditions. The modified Rankin score (mRS) and Glasgow Outcome Scale (GOS) are most commonly used. Employment of these scales in SAH is hampered by well-recognised limitations. We set out to develop and validate a new condition-specific SAH Outcome Tool (SAHOT). Items addressing diverse aspects of the impact of SAH were collected during focus groups involving patients, next-of-kin and multidisciplinary professionals involved in SAH management. After a series of iterative revisions, the resultant questionnaire was applied to patients and their next-of-kin at one, three and six months post-SAH. Rasch methodology was utilized to finalize the structure of the questionnaire and explore the extent to which SAHOT scores met Rasch-based criteria of successful measurement. The SAHOT was further assessed using traditional scale evaluation techniques, and validated in a second separate SAH patient cohort. The final SAHOT included 56 items dealing with cognitive, physical, and behavioural/psychological consequences of SAH. Rasch analysis indicated the scale successfully measured functional outcome post-SAH. Three item scoring categories produced the best scale performance. There was no evidence of differential item functioning between patients and next-of-kin. The SAHOT was found to be acceptable, have good convergent and divergent validity, good discrimination and excellent responsiveness. It was successfully validated in a second SAH patient cohort. The SAHOT offers the first SAH-specific scientifically robust outcome measure with potential utility in neurovascular clinical services and research studies.

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Identifiers

ORCID for Diederik Bulters: orcid.org/0000-0001-9884-9050

ORCID for Ian Galea: orcid.org/0000-0002-1268-5102

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