Patient Specific Complaints

Abstract

The Patiënt Specifieke Klachten (PSK), or Patient-Specific Complaints, is a robust measurement instrument designed to determine the functional status of an individual patient based on their self-identified physical limitations. The core methodology requires the patient to select between three and five activities that are most critical to them, where they experience significant hindrance, and which they perform regularly (ideally weekly). This patient-centered approach ensures that the functional assessment is highly relevant to the individual’s daily life and specific condition. Originally developed in 1996 to assess patients suffering from low back pain, the PSK has since been adapted for various chronic conditions, including Parkinson’s disease, claudicatio intermittens, chronic ankle injuries, and heart complaints, with specific versions developed in 2006. Scoring involves the patient rating the degree of perceived hindrance on an 11-point Numeric Rating Scale (NRS), a change implemented in 2008 from the original VAS-line scoring method.

Keywords

Patient-Specific Complaints, PSK, Numeric Rating Scale, functional status, physical activity, outcome measure, self-report, individualized assessment, low back pain, Parkinson’s disease

Authors

Beurskens AJHM (1996)

Purpose

The primary purpose of the Patiënt Specifieke Klachten (PSK) instrument is to function as an individualized, patient-centered outcome measure. It moves beyond standard, generic activity checklists by allowing the patient to define the specific functional domains that are most important and challenging to them. This provides clinicians and researchers with a highly relevant baseline of the patient’s current functional limitations.

By focusing on self-selected activities that are performed frequently and cause significant difficulty, the PSK enables the precise monitoring of change over time, particularly in response to therapeutic interventions. This makes the PSK a valuable tool for determining the effectiveness of treatment plans in rehabilitation, physiotherapy, and chronic disease management, where improvements in specific daily functions are key indicators of success.

Construct

The PSK measures the psychological construct of perceived functional limitation and participation restriction, specifically within the context of physical activities. It aligns closely with the World Health Organization’s International Classification of Functioning, Disability and Health (ICF) framework, focusing on the domains of Activities and Participation.

The scale captures the subjective severity of difficulty experienced by the patient while performing self-nominated, high-priority physical tasks. Because the patient determines the relevance of the items, the construct is inherently patient-specific, reflecting the impact of the underlying condition (such as low back pain or Parkinson’s disease) on their unique daily life and functional goals. The resultant score is a quantitative measure of subjective disability or hindrance.

Validity

The validity of the PSK rests heavily on its inherent content validity, as the items measured are directly chosen by the patient, ensuring high relevance to their individual functional experience. Studies typically investigate the scale’s ability to correlate with established, general functional measures (concurrent validity) and its capacity to differentiate between groups of varying disability (discriminant validity).

Crucially, the PSK demonstrates high responsiveness, which is vital for an outcome measure. Its sensitivity to change is often superior to that of generic scales, as it tracks improvements in the specific activities the patient cares about most. This responsiveness confirms its utility in clinical settings for detecting genuine functional improvement following rehabilitation or other medical interventions.

Reliability

The reliability of the Patiënt Specifieke Klachten is generally assessed through inter- and intra-rater reliability, although test-retest reliability is particularly important for self-report measures. High test-retest reliability suggests that if the patient’s functional status has not changed, the scores assigned to the self-nominated activities remain consistent across administrations.

Given the individualized nature of the scale, the reliability is dependent not just on the scoring mechanism (the 11-point NRS) but also on the clarity of the patient’s definition of the chosen activities. Research confirms that when clear instructions are followed regarding the selection of relevant, frequent, and hindered activities, the PSK maintains acceptable levels of reliability across diverse patient populations.

Factor Analysis

Due to the unique, individualized nature of the PSK, traditional factor analysis methods, which rely on fixed item sets, are generally not directly applicable to the scale itself. The instrument does not contain a fixed set of items that are intended to load onto latent factors. Instead, the PSK is treated as a single, individualized index score (the average difficulty rating across the 3 to 5 chosen activities).

However, factor analytic techniques may be employed in studies utilizing the PSK to explore whether underlying common factors (e.g., mobility, self-care, recreation) emerge across the *types* of activities patients select when stratified by specific diagnostic groups (e.g., patients with claudicatio intermittens versus patients with chronic ankle instability). This analysis helps validate the appropriateness of the instrument across different clinical populations.

Instrument

Test Type: Vragenlijst (Questionnaire / Self-report measure)

Format: The format involves the patient selecting 3 to 5 specific, problematic activities and then rating the difficulty of these activities on an 11-point Numeric Rating Scale (0 = no difficulty; 10 = impossible).

Language Available: Primarily Dutch (Patiënt Specifieke Klachten). Translations and adaptations exist for various international studies.

Population Group: Adults, Elderly

Age Group: Typically utilized with adult populations experiencing chronic or acute physical limitations.

Population Details: Originally developed for patients with musculoskeletal issues, specifically low back pain. Subsequently adapted for neurological and vascular conditions, including Parkinson’s disease, claudicatio intermittens, chronic ankle injury, and cardiac complaints.

Test Methodology: Patients identify activities meeting three criteria: relevance/importance, frequency (weekly performance), and significant perceived hindrance during execution. The average score across the selected activities yields the final PSK index score.

Keywords

Functional limitations, self-selected activities, individualized outcome, activities of daily living, Beurskens, physical functioning, rehabilitation assessment, PSK

Authors

Author ORCID Identifier: Information not provided in the source content.

Affiliation Email addresses: Information not provided in the source content.

Correspondence Address: Information not provided in the source content.

Permissions & Fee and Test Year

The scale was originally published by Beurskens AJHM in 1996. The scoring methodology was formally updated in 2008, moving from a VAS-line to an 11-point NRS. Information regarding current usage permissions and associated fees should be sought directly from the primary author or relevant academic bodies specializing in health outcome measures.

Supporting documentation for the scale can be accessed via the following links:

• The original Toelichtingsformulier (Explanation Form) PDF can be downloaded here: PSK-form.pdf
• The Parkinson-specific Toelichtingsformulier (Explanation Form) PDF can be downloaded here: PSK-form-ZvP-3.pdf
• The original Meetinstrument (Measurement Instrument) PDF can be downloaded here: PSK-meetinstr.pdf
• The Parkinson-specific Meetinstrument (Measurement Instrument) PDF can be downloaded here: PSK-meetinstr-ZvP-2.pdf

Reference’s

Beurskens AJHM (1996). Patiënt Specifieke Klachten (PSK). Specific reference details are typically found in subsequent publications validating the instrument’s use across different patient groups (e.g., studies published around 2006 detailing the specialized lists, or 2008 detailing the NRS transition).

Items of the Patiënt Specifieke Klachten

IMPORTANT: The following scale items must be preserved in their original language and must not be changed in any way.

The PSK does not contain fixed items but requires the patient to define their own. The patient selects the 3 to 5 most important complaints on the area of physical activities. These activities must be relevant (important), the patient must experience hindrance during execution, and the execution must occur regularly (weekly).

The scoring is based on an 11-point Numeric Rating Scale (NRS) where:

• 0 = Geen hinder (No hindrance)
• 10 = Onmogelijk (Impossible)