The Key Characteristics of Functional Impairment as Evidenced by Psychometric Studies of the WFIRS

Over the last decade, the Weiss Functional Impairment Rating Scale (WFIRS) has been the primary focus of 7 psychometric investigations in different countries, languages, clinical, research and population settings, and informants. This collective information provides a base for extrapolating key characteristics of functional impairment. High domain to domain, domain to total score and internal consistency suggest that there is a meaningful total score for impairment. The high test-retest reliability suggests that patients are able to reliably report on how their emotional and behavioral symptoms or those of their children impact their functioning. Cross informant studies between adolescents and parents indicate that differences require evaluation by multiple informants. Moderate convergent validity between WFIRS with symptom, quality of life, adaptive life skill and symptom measures as well as similar subdomains within these scales suggest that these measures capture overlapping but nonetheless distinct outcomes. Factor analytic studies validating the domains constructed based on face validity suggest that functional impairment is best measured in such as way as to identify strengths and weaknesses to shape targeted interventions.