The Internet Intervention Patient Adherence Scale (iiPAS) is a brief, validated, clinician-rated measure of treatment adherence in guided internet-delivered behavioral interventions, including internet-based cognitive behavioral therapy (ICBT).
The iiPAS consists of five items assessing how actively patients engage with and follow their online treatment. It was developed at Karolinska Institutet, Sweden, to provide researchers and clinicians with a practical and scientifically evaluated alternative to simple usage metrics such as logins and completed treatment modules.
The iiPAS is freely available for non-commercial use, including academic research.
Download the iiPAS questionnaire
The iiPAS is available in English and Swedish. Both versions include the questionnaire and instructions for administration and scoring.
What is the iiPAS?
Measuring patient adherence is an important challenge in digital mental health interventions. Researchers frequently assess adherence using automatically collected platform data, such as the number of completed modules, logins, or time spent online.
However, these indicators do not necessarily capture the extent to which patients actively engage with the therapeutic content or apply treatment strategies.
The Internet Intervention Patient Adherence Scale (iiPAS) was developed to assess treatment adherence more comprehensively, combining observable treatment activity with clinically meaningful aspects of patient engagement.
The scale covers five dimensions of adherence:
- Pace of work – Whether the patient follows the intended treatment schedule.
- Involvement in exercises – The extent to which the patient actively engages with therapeutic exercises.
- Communication with the treatment provider – The patient’s participation in therapeutic communication.
- Motivation for change – The extent to which the patient actively applies treatment strategies.
- Login frequency – The patient’s activity on the internet treatment platform.
The iiPAS is completed by the treating clinician or therapist, rather than the patient. It was designed for guided internet-delivered interventions and can be applied to children, adolescents, and adults.
Psychometric validation and scientific evidence
The iiPAS was developed and psychometrically evaluated in a study published in the Journal of Medical Internet Research (Lenhard et al., 2019).
Following an initial evaluation in 50 participants, the revised scale was evaluated in 148 children and adolescents receiving internet-delivered cognitive behavioral interventions for various mental health conditions.
The study demonstrated:
- Excellent internal consistency: Cronbach’s alpha of .93 at mid-treatment and .95 at post-treatment.
- A unidimensional factor structure: A single underlying factor explained approximately 80% of the variance.
- Convergent validity: iiPAS scores were strongly associated with objective platform activity measures.
- Associations with treatment outcomes: Higher iiPAS scores were significantly associated with better treatment outcomes.
Notably, conventional platform metrics, including logins, written characters, and completed modules, were not significantly associated with treatment outcomes in the same sample.
These findings suggest that iiPAS may capture clinically relevant aspects of adherence that are not adequately reflected by simple measures of platform usage.
The original validation focused on children and adolescents receiving ICBT. Although the instrument was designed for use across age groups, further psychometric evaluation in adults, other intervention formats, and different clinical settings remains valuable.
Read the original validation study – Open Access
Administration and scoring
The iiPAS contains five clinician-rated items, each scored from 0 to 4.
Total score: 0–20
Higher scores indicate greater adherence to the intended treatment.
The instrument was originally evaluated at two assessment points:
- Mid-treatment: Adherence from treatment initiation to the midpoint.
- Post-treatment: Adherence from the midpoint to treatment completion.
Additional assessments, for example weekly ratings, are possible.
Importantly, adherence should be evaluated relative to the intended treatment structure. For example, optimal login frequency may differ between interventions.
To improve consistency, clinicians using the iiPAS within a study should agree in advance on how the response categories relate to the specific treatment protocol.
The downloadable questionnaires include the original scoring and administration instructions.
Applications in research and clinical practice
The iiPAS may be useful for researchers and clinicians working with:
- Internet-delivered cognitive behavioral therapy (ICBT)
- Guided online psychotherapy
- Digital mental health interventions
- Therapist-supported eHealth interventions
- Behavioral intervention and treatment adherence research
- Clinical trials evaluating patient engagement and treatment outcomes
Potential applications include measuring adherence during treatment, examining relationships between adherence and clinical outcomes, and evaluating strategies designed to improve patient engagement.
The iiPAS is specifically designed for guided interventions involving clinician or therapist support. Its applicability to fully unguided self-help programs has not been established.
Using the iiPAS in your research
The iiPAS is available free of charge for non-commercial use, including academic research. Researchers using the instrument are asked to cite the original validation study.
For permission requests relating to commercial applications, modifications, or translations, please contact the corresponding author.
Researchers interested in further validation, translation, or collaborative studies are welcome to get in touch.
Frequently asked questions
Is iiPAS free to use in research?
Yes. The iiPAS is freely available for non-commercial use, including academic research.
Is the iiPAS a self-report questionnaire?
No. The iiPAS is a clinician-rated instrument, intended to be completed by the therapist or clinician supporting the patient’s internet-delivered treatment.
How is iiPAS different from measuring completed treatment modules?
Module completion captures one aspect of treatment participation. The iiPAS additionally evaluates engagement with therapeutic exercises, communication, motivation, and adherence to the intended treatment schedule.
Can iiPAS be used with adults?
The iiPAS was designed for children, adolescents, and adults. However, the original psychometric validation was conducted in children and adolescents, and additional validation in adult populations is encouraged.
Can iiPAS be used to monitor adherence during treatment?
Yes. The scale was evaluated at mid-treatment and post-treatment, and its instructions also allow for more frequent assessments.
Is iiPAS suitable for unguided internet interventions?
The iiPAS was developed for guided, clinician-supported interventions. Application to entirely unguided interventions would require additional evaluation or adaptation.
How to cite the iiPAS
Lenhard F, Mitsell K, Jolstedt M, Vigerland S, Wahlund T, Nord M, Bjureberg J, Sahlin H, Andrén P, Aspvall K, Melin K, Mataix-Cols D, Serlachius E, Högström J. (2019). The Internet Intervention Patient Adherence Scale for Guided Internet-Delivered Behavioral Interventions: Development and Psychometric Evaluation. Journal of Medical Internet Research, 21(10), e13602. DOI: https://doi.org/10.2196/13602
The iiPAS was developed by Fabian Lenhard and colleagues at Karolinska Institutet, Sweden. For questions regarding the instrument, research collaborations, translations, or permissions, contact fabian.lenhard@ki.se.
