Diagnosis of TIA (DOT) score – design and validation of a new clinical diagnostic tool for transient ischaemic attack

BMC Neurology, Feb 2016

Background The diagnosis of Transient Ischaemic Attack (TIA) can be difficult and 50–60 % of patients seen in TIA clinics turn out to be mimics. Many of these mimics have high ABCD2 scores and fill urgent TIA clinic slots inappropriately. A TIA diagnostic tool may help non-specialists make the diagnosis with greater accuracy and improve TIA clinic triage. The only available diagnostic score (Dawson et al) is limited in scope and not widely used. The Diagnosis of TIA (DOT) Score is a new and internally validated web and mobile app based diagnostic tool which encompasses both brain and retinal TIA. Methods The score was derived retrospectively from a single centre TIA clinic database using stepwise logistic regression by backwards elimination to find the best model. An optimum cutpoint was obtained for the score. The derivation and validation cohorts were separate samples drawn from the years 2010/12 and 2013 respectively. Receiver Operating Characteristic (ROC) curves and area under the curve (AUC) were calculated and the diagnostic accuracy of DOT was compared to the Dawson score. A web and smartphone calculator were designed subsequently. Results The derivation cohort had 879 patients and the validation cohort 525. The final model had seventeen predictors and had an AUC of 0.91 (95 % CI: 0.89–0.93). When tested on the validation cohort, the AUC for DOTS was 0.89 (0.86–0.92) while that of the Dawson score was 0.77 (0.73–0.81). The sensitivity and specificity of the DOT score were 89 % (CI: 84 %–93 %) and 76 % (70 %–81 %) respectively while those of the Dawson score were 83 % (78 %–88 %) and 51 % (45 %–57 %). Other diagnostic accuracy measures (DOT vs. Dawson) include positive predictive values (75 % vs. 58 %), negative predictive values (89 % vs. 79 %), positive likelihood ratios (3.67 vs. 1.70) and negative likelihood ratios (0.15 vs. 0.32). Conclusion The DOT score shows promise as a diagnostic tool for TIA and requires independent external validation before it can be widely used. It could potentially improve the triage of patients assessed for suspected TIA.

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Diagnosis of TIA (DOT) score – design and validation of a new clinical diagnostic tool for transient ischaemic attack

Dutta BMC Neurology Diagnosis of TIA (DOT) score - design and validation of a new clinical diagnostic tool for transient ischaemic attack Dipankar Dutta 0 0 Stroke Service, Gloucestershire Royal Hospital , Great Western Road, Gloucester GL1 3NN , UK Background: The diagnosis of Transient Ischaemic Attack (TIA) can be difficult and 50-60 % of patients seen in TIA clinics turn out to be mimics. Many of these mimics have high ABCD2 scores and fill urgent TIA clinic slots inappropriately. A TIA diagnostic tool may help non-specialists make the diagnosis with greater accuracy and improve TIA clinic triage. The only available diagnostic score (Dawson et al) is limited in scope and not widely used. The Diagnosis of TIA (DOT) Score is a new and internally validated web and mobile app based diagnostic tool which encompasses both brain and retinal TIA. Methods: The score was derived retrospectively from a single centre TIA clinic database using stepwise logistic regression by backwards elimination to find the best model. An optimum cutpoint was obtained for the score. The derivation and validation cohorts were separate samples drawn from the years 2010/12 and 2013 respectively. Receiver Operating Characteristic (ROC) curves and area under the curve (AUC) were calculated and the diagnostic accuracy of DOT was compared to the Dawson score. A web and smartphone calculator were designed subsequently. Results: The derivation cohort had 879 patients and the validation cohort 525. The final model had seventeen predictors and had an AUC of 0.91 (95 % CI: 0.89-0.93). When tested on the validation cohort, the AUC for DOTS was 0.89 (0.86-0.92) while that of the Dawson score was 0.77 (0.73-0.81). The sensitivity and specificity of the DOT score were 89 % (CI: 84 %-93 %) and 76 % (70 %-81 %) respectively while those of the Dawson score were 83 % (78 %-88 %) and 51 % (45 %-57 %). Other diagnostic accuracy measures (DOT vs. Dawson) include positive predictive values (75 % vs. 58 %), negative predictive values (89 % vs. 79 %), positive likelihood ratios (3.67 vs. 1.70) and negative likelihood ratios (0.15 vs. 0.32). Conclusion: The DOT score shows promise as a diagnostic tool for TIA and requires independent external validation before it can be widely used. It could potentially improve the triage of patients assessed for suspected TIA. Transient ischaemic attack; Diagnosis; Diagnostic score; Logistic regression Background The diagnosis of transient ischaemic attack (TIA) can be difficult and studies show limited inter-observer agreement for clinical diagnosis [ 1 ]. About 50 to 60 % of TIA referrals by non- specialists turn out to be noncerebrovascular mimics [ 2–4 ]. Patients with TIA have a high risk of early stroke and subsequent adverse events [ 5, 6 ]. Following secondary prevention studies [ 7, 8 ] and the introduction of the ABCD2 score [ 9 ], rapid assessment TIA clinics have been set up to investigate and manage TIA. Inappropriate referrals to TIA clinics, however, can lead to delays for patients with TIA and the misdiagnosis of non -cerebrovascular conditions as TIA leads to unnecessary anxiety and inappropriate initial management. Stroke diagnostic tools such as FAST and ROSIER have been developed for use by pre hospital assessors and emergency room clinicians [ 10, 11 ]. The ABCD2 score, too, has been used as a crude diagnostic aid for TIA [12]. More recently, the ability of the ABCD2 score to reliably discriminate between those at high or low risk after a TIA has been called into question and a third of mimics found to have ABCD2 scores ≥ 4 [ 13 ]. A TIA diagnostic tool could be used to improve TIA clinic triage by removing some mimics from urgent TIA pathways. There is only one TIA diagnostic tool, the score of Dawson and colleagues [ 14 ] which was not designed for retinal and some posterior circulation events and is not widely used. It has shown limited accuracy when used in a primary care setting [ 15 ]. The Diagnosis of TIA Score (DOTS) is a new tool to help non-specialists make the diagnosis of TIA with greater accuracy. It includes retinal and posterior circulation events and is meant for use as a mobile app and web based calculator. Methods Development cohort The development cohort for the score was a subset of TIA clinic patients studied retrospectively from a TIA database [ 2 ]. Briefly, all patients referred to the Monday to Friday TIA clinics of Gloucestershire Royal Hospital (GRH), Gloucester, UK between April 2010 and May 2012 were eligible for inclusion in the development cohort. The catchment area for GRH has a population of 560,000. Referrals are accepted from Emergency Departments, General Practitioners, paramedics and other departments such as ophthalmology. Data collected included demographic information, past medical history, a detailed history, examination findings, ABCD2 scores, results of investigations (blood tests, ECG, same day carotid duplex ultrasounds, same day (...truncated)


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Dipankar Dutta. Diagnosis of TIA (DOT) score – design and validation of a new clinical diagnostic tool for transient ischaemic attack, BMC Neurology, 2016, pp. 20, 16, DOI: 10.1186/s12883-016-0535-1