About the Patient-Specific Functional Scale
The Patient-Specific Functional Scale (PSFS) is a patient-centred outcome measure that allows you to identify and rate the difficulty of specific activities that are important to you. Unlike standardised questionnaires, the PSFS lets you choose activities that matter most to your daily life, making it a highly personalised tool for tracking your functional progress over time. This approach helps your healthcare team understand your unique challenges and measure meaningful improvements in activities that directly impact your quality of life.
Medical Specialties
Anatomic Areas
Clinical Indications
Developer Information
Developed by Paul W. Stratford, Carolyn Gill, Michael Westaway, and Jennifer Binkley in 1995 at McMaster University, Ontario, Canada. First published in: Stratford P, Gill C, Westaway M, Binkley J. Assessing disability and change on individual patients: a report of a patient specific measure. Physiotherapy Canada. 1995;47(4):258-263.
Copyright & Licensing
The Patient-Specific Functional Scale is in the public domain and freely available for clinical and research use without licensing fees or copyright restrictions. It may be used, reproduced, and modified without permission.
Administration Instructions
Please add up to 5 activities that are important to your daily life, then rate your current difficulty with each activity on a scale from 0 (able to perform activity at same level as before injury or problem) to 10 (unable to perform activity).
Scoring Methodology
Patients identify up to 5 activities that are important to them and that they find difficult due to their condition. Each activity is rated on an 11-point numerical scale from 0 to 10 where 0 is able to perform the activity at the same level as before the injury or problem and 10 is unable to perform the activity. The mean difficulty rating across activities is stored as PSFS Average Score (also 0 to 10). Lower scores indicate less difficulty and therefore better function. The scale can be administered at multiple time points to track change.
Meaningful Change Threshold
A decrease of 2 points or more in difficulty on an individual activity is often considered the minimal clinically important difference (MCID). For the mean difficulty score across activities, a decrease of 2 points is also commonly regarded as clinically meaningful improvement.
Score Interpretation
Understanding what your score means
excellent
0 - 2Minimal difficulty; activity performance close to pre-injury levels.
good
3 - 4Mild difficulty with the activity.
moderate
5 - 6Moderate difficulty performing the activity.
poor
7 - 9Severe difficulty; marked limitation performing the activity.
unable
10Unable to perform the activity due to the condition.
Clinical Limitations & Considerations
The PSFS has several limitations to consider: (1) Floor effects may occur when patients identify activities they are already unable to perform, limiting the ability to detect further functional decline. (2) The individualised nature of the scale means scores cannot be directly compared between patients, as each person rates different activities. (3) Some patients may find it challenging to rate activities on a numerical scale or may select activities that are too broad or vague. (4) The scale relies on patient self-report and subjective perception, which may not correlate perfectly with objective functional measures. (5) Cultural or language differences may affect how patients interpret and use the rating scale.
Supporting Literature
Key validation and development studies for the Patient-Specific Functional Scale
- 1
Assessing disability and change on individual patients: a report of a patient specific measure
Stratford PW, Gill C, Westaway M, Binkley J
Physiotherapy Canada, 1995
Used in Literature
Studies and publications that have used the Patient-Specific Functional Scale
- 1
Assessing disability and change on individual patients: a report of a patient specific measure
Stratford PW, Gill C, Westaway M, Binkley J
Physiotherapy Canada, 1995
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This questionnaire is provided free of charge. Patient Watch charges only for platform services (data storage, automated reminders, analytics) - not for use of clinical instruments. This non-commercial model supports academic and clinical use. View full licensing disclosure