[The "National Aeronautics and Space Administration-Task Load Index" (NASA-TLX) - an instrument for measuring consultation workload within general practice: evaluation of psychometric properties]

Abstract

Objective: The aims of the study were the translation and a first reflection of the psychometric properties of the Aeronautics and Space Administration-Task Load Index (NASA-TLX), a multidimensional instrument to measure workload in general practice.

Methods: During April and September 2015, the NASA-TLX was translated and evaluated. For this purpose, a questionnaire composed of the NASA-TLX items and others items related to demographic data, was developed. Postgraduate family medicine trainees and family physicians were then asked to assess patient consultations by applying the questionnaire. The psychometric properties of the NASA-TLX were identified using explorative and confirmatory factor analysis. Reliability was assessed using Cronbach's α.

Results: Overall, 16 participants completed 769 surveys after a single patient consultation. The highest average was observed for the item 'mental demand' (mean 6.9 ± 5.4), followed by the item 'effort' (mean 6.6 ± 5.5). Factor analysis revealed a one-factor solution with an explained variance of 56.9 %. The German version of NASA-TLX demonstrated a high internal consistency (Cronbach's α = 0.84). Confirmatory factor analysis showed that there was an acceptable consistency between the expected unidimensional structure and the data.

Conclusions: The German version of NASA-TLX provides preliminary indications of psychometric properties and presents an important tool to evaluate family physicians' workload in direct patient contact.

Keywords: Allgemeinmedizin; Arbeitsbelastung; Complexity; General practice; Komplexität; NASA-TLX; Postgraduate training; Weiterbildung; Workload.