Validation of screening instruments for neuroepidemiological surveys of tic disorders

Abstract

Background: The main purpose was to validate a multistage protocol to screen tic disorders in mainstream and special education centers and to investigate whether telephone-based interviews were accurate to diagnose tic disorders when compared with in-person neurological interviews.

Methods: A school-based survey of children and adolescents (6-16 years). A proxy report questionnaire for tic disorders was completed by teachers, observers, and parents. The diagnosis was confirmed by the neurologist based on the Diagnostic and Statistical Manual of Mental disorders (DSM-IV TR) criteria. The sensitivity, specificity, positive and negative predictive values, the likelihood ratio for a positive result (LR+), and the Kappa coefficients (k) for telephone-based interviews reliability were calculated.

Results: One hundred twenty subjects, 57 from special education center and 63 from a mainstream school were studied. The sensitivity of the proxy report questionnaire was 58% and 36% when completed by the observers (mainstream and special education center, respectively), 40 and 73% when completed by the teachers, and 58 and 36% when completed by the parents. Using any of these 3 screening sources, the sensitivity was 92%, the positive predictive value was 38%, and negative predictive value was 97% (mainstream schools), whereas the sensitivity was 82%, the positive predictive value was 20%, and negative predictive value was 82% (special education centers). Parents (mainstream schools) and teachers (special education center) produced the highest LR+ (7.25 and 1.26, respectively) and the intraobserver reliability of the telephone-based interviews versus in-person neurological interviews gave a k coefficient of 0.83.

Conclusions: The efficiency of different screening instruments for tic disorders seems to vary in different settings. Telephone-based interviews may be a valid and convenient backup to ascertain the diagnosis of tic disorders when face-to-face neurological examination is not possible.