Validity and Reliability of the Thrombolysis in Brain Infarction (TIBI) Flow Grades
Background: In patients eligible for thrombolytic therapy, the TIBI grading system defines residual transcranial Doppler (TCD) flow signals at the site of clot location. In addition, TIBI flow grades correlate with angiography and predict short-term improvement following TPA therapy. The aim of this study was to develop a valid and reliable instrument to assess how accurately health professionals determine TIBI flow grades. Methods: Two expert sonographers developed a 60 question computerized examination of the 6 TIBI flow grades. Gold standard interpretation was determined by a consensus interpretation by a pool of expert sonographers. All items were equally weighted and written in a standard format. A computerized TIBI grading tutorial and standard interpretation rules were available for all test-takers. To assess content validity and reliability, a blinded panel of 3 experts independently took the examination. Inter-rater agreement was determined among experienced sonographers, stroke neurologists, and other health professionals (N=11). Results: Expert assessment of each test item measured objective congruence at 1.0, overall test validity coefficient of 0.996 (95%CI 0.993–0.997), and an item/TIBI flow grade validity coefficient of 0.992 (95%CI 0.996–0.997). Overall test and individual item reliability had coefficients of 0.98(95%CI 0.97–0.99) and 0.97 (95%CI 0.95–0.98, p<0.0001) respectively. Inter-rater agreement was 0.89 (coefficient of contingency) and 0.86 (kappa) for all participants. Kappa range included 0.98 for an experienced interpreter, 0.81–0.89 for stroke neurologists with beginner experience in TCD and 0.65 for those without previous TCD experience (66% of correct answers after 1 hour tutorial). Conclusions: Our computerized examination is a valid and reliable tool to assess an individuals ability to score TIBI flow grades. In addition, TIBI flow grade evaluation has a high degree of inter-rater reliability, even among those with limited experience in ultrasound.