TIA and the urgency of assessment: Is relying on ABCD2 scoring by non-specialists adequate?

Abstract

Background: The high risk of stroke following transient ischaemic attack (TIA) has made it crucial for higher-risk (HR) patients to be referred promptly for specialist management. The National Stroke Strategy for England states that TIA patients with ABCD2 score >4 should be managed by a specialist within 24 hours, and those with a lower score within 1 week. In this context, ABCD2 scores are calculated mostly by primary-care physicians. However, ABCD2 validation is based upon specialist assessment in a secondary-care setting. Non-specialist assessment of TIA patients may differ due to lower levels of experience and available consultation time. Methods: Request for specialist assessment in a rapid-access TIA clinic was made via a standardized referral form requiring the referring-clinician to complete each element of the ABCD2 score. 342 patients referred in this manner received a final diagnosis of TIA or minor stroke (NIH<1) by a consultant stroke physician. Patients reporting >1 neurological episode were excluded and all assessments completed within 1 week of referral. Referrer (1o care) and specialist (2o care) ABCD2 scores were compared. Results: A significantly higher number of HR patients were identified in the TIA clinic, 1o care 62%, 2o care 67%, p=0.04. The negative predictive value of a referrer-derived score on the identification of a HR patient was 64%. Measures of inter-observer agreement between 1o and 2o care for age (A), BP (B), clinical features (C), duration (D) and diabetes (D2) were 0.90, 0.41, 0.68, 0.68, and 0.92 respectively (Cohen's kappa). Conclusions: There was significant disparity between 1o and 2o care ABCD2 scores, driven by variation in recorded BP, clinical features and symptom-duration. Over one-third of patients were re-assigned from lower to a HR score following specialist assessment. Provision of an urgent assessment service for TIA in accordance with recommended guidelines may not be able to rely upon a non-specialist derived ABCD2 score.