Table 3.

Types of validated questionnaires commonly used to evaluate usability of eHealth interventions

Questionnaires	Description	Benefits & Challenges
System Usability Scale (SUS)[51]	A widely used and quick usability assessment scale. Participants are asked to score 10 items with a five-point scale ranging from strongly agree to strongly disagree.	The overall score can be complex to interpret. This is meant to be a quick and rough estimate of perceived usability.
Health Information Technology Usability Evaluation Scale (Health-ITUES)[52]	A customizable usability assessment instrument where the participants are asked to score 20 items with a 5-point scale ranging strongly disagree to strongly agree. The questionnaire is comprised of four subscales: (1) quality of work life, (2) perceived usefulness, (3) perceived ease of use, and (4) user control.	This questionnaire is customizable to health system and the needs of a study. However, it is one of the longer questionnaires to administer.
Post-Study System Usability Questionnaire (PSSUQ)[53]	The PSSUQ consists of 19 items rated on a 7-point scale ranging from strongly agree to strongly disagree and includes an additional option for „not applicable‟ (N/A). The questionnaire addresses the following components of usability: quick completion of work, ease of learning, high-quality documentation, high quality online information, functional adequacy, rapid acquisition of usability experts, and rapid acquisition of several different user groups.	There is a 7-point scale which allows end-users to give a nuanced response compared to the 5-point scale.
Website Analysis and Measurement (WAMMI)[46]	The WAMMI questionnaire uses a standardized 20-item assessment to evaluate user experience and assesses user satisfaction. The participants rate items on a five-point scale from strongly agree to strongly disagree. The items are scored to produces five subscales measuring attractiveness, controllability, efficiency, helpfulness, and learnability of the website.	This instrument specifically recommended for use with websites and is one of the longer assessment tools that is available.
IBM Computer System Usability Questionnaire (CSUQ)[54]	A scenario-based psychometric questionnaire developed to assess subjective usability and end-user‟s reactions to the eHealth intervention. Participants rate items on a Likert scale, ranging from 1 to 7.	This is a 7-point scale which allows end-users to give a nuanced response compared to the 5-point scale. This instrument can be used within scenario-based usability.