Preliminary validation of the Claudication Symptom Instrument (CSI)

Area of Science:

• Vascular Medicine
• Patient-Reported Outcomes
• Instrument Development

Background:

• Intermittent claudication (IC) significantly impacts patients' quality of life.
• Accurate assessment of IC symptoms is crucial for effective treatment and management.
• Existing instruments may not fully capture the patient's symptom experience.

Purpose of the Study:

• To develop and validate the Claudication Symptom Instrument (CSI) for assessing IC symptoms.
• To evaluate the measurement properties of the CSI, including content validity, reliability, and validity.
• To establish the CSI's utility in clinical practice and research.

Main Methods:

• Qualitative interviews with IC patients for item generation.
• Cognitive interviews to test item comprehension.
• Rasch analysis and statistical evaluation of measurement properties using observational study data.

Main Results:

• Developed and cognitively tested items for five key symptoms: Pain, Numbness, Heaviness, Cramping, and Tingling.
• Rasch analysis supported an overall CSI score (χ²=26.5, df=20, p=0.15).
• Demonstrated good test-retest reliability (ICC=0.86) and sensitivity to change, correlating with VASCUQOL scores (r=-0.52, p<0.05).

Conclusions:

• The CSI preliminarily meets accepted standards for content validity, reliability, construct validity, and sensitivity.
• The CSI is a reliable and valid instrument for evaluating the symptom experience in patients with intermittent claudication.
• Its high test-retest reliability suggests utility in individual patient clinical care, with a completion time of approximately 3 minutes.