Assessing the Usability of Complex Psychosocial Interventions: The Intervention Usability Scale

Area of Science:

• Health Services Research
• Psychology
• Implementation Science

Background:

• Usability is critical for successful implementation of health interventions.
• Few instruments exist to measure the design quality of complex health interventions.
• This study focuses on the Intervention Usability Scale (IUS), adapted from the System Usability Scale (SUS).

Purpose of the Study:

• To evaluate the structural validity of the Intervention Usability Scale (IUS).
• To measure the usability of Motivational Interviewing (MI), a complex psychosocial intervention.
• To assess the IUS's suitability for behavioral health service delivery in primary care.

Main Methods:

• A survey was administered to 136 medical professionals across 11 primary care sites.
• Participants provided IUS ratings for Motivational Interviewing (MI).
• Factor analyses were conducted, examining one- and two-factor solutions.

Main Results:

• A two-factor solution, comprising "usable" and "learnable" subscales, best fit the data.
• This structure accounted for 54.1% of the variance.
• Inter-item reliabilities were acceptable (α = .83 total, α = .84 usable, α = .67 learnable).

Conclusions:

• The study provides evidence for a reliable two-factor IUS structure.
• The IUS can be used to evaluate the usability of complex health interventions.
• Findings support the IUS's utility in implementation research, linking usability to feasibility.