Development of a new questionnaire to assess mental workload in the return-to-work process

Introduction
Long recognized as a key factor in human performance, mental workload is a psychosocial factor contributing to work disability. Actual assessment tools do not differentiate among underload, overload and optimal load. This lacking results in a more complex exposure-to-work decision-making process for the clinicians. A new questionnaire was developed to assess mental workload in the return-to-work process.

Methods
The items were first written based on a literature review following the steps of a concept analysis, then revised by experts (n= 16) for relevance and clarity, through a two-round Delphi method. Experts were selected according to defined criteria: 1) working as a clinician or as a researcher in a field related to work rehabilitation for at least 3 years and 2) proficiency in writing and reading comprehension of French. The median and interquartile range were used to determine the expert's agreement level on relevance and clarity.

Results
The questionnaire was originally composed of 44 items related to effort and effects on the mental state to cover mental workload's attributes in a work consequence perspective. Nine items related to work characteristics, recovery and fatigue were also created to help discriminate between underload and overload. Following the Delphi, five items were rejected to reduce the redundancy and 14 items were added. Experts agreed on a high relevance of the items and on an acceptable level of clarity.

Discussion
Mental workload is complex to assess and little is known about the optimal mental workload. The new questionnaire is a first step towards an operational definition of the construct. It would be useful to assess mental workload in the return-to-work process according to a work consequence perspective. Further research is needed to better understand the optimal mental workload, as well as to determine the psychometric qualities of the questionnaire.