Psychometric Evaluation of a New Patient-Reported Outcome (PRO) Symptom Diary for Varicose Veins: VVSymQ(®) Instrument.Patient. 2016 08; 9(4):335-48.P
To evaluate the psychometric properties of the VVSymQ(®) instrument, a new 5-item patient-reported outcome (PRO) measure for symptoms of varicose veins.
The VVSymQ(®) electronic daily diary was administered to outpatients who received routine treatment for varicose veins (N = 40). Compliance with diary administration and item score variability, reliability, construct validity, sensitivity to change, and clinically meaningful change were evaluated.
Patients completed >97 % of scheduled diary assessments (at screening, baseline, and week 8). The VVSymQ(®) instrument captured patients' pre-treatment symptoms (all VVSymQ(®) symptoms were endorsed by ≥75 % of patients at baseline), and the change post-treatment (mean change in score -6.1), with a large Cohen effect size (1.6). Test-retest reliability was high (intraclass correlation coefficient 0.96); internal consistency was good (Cronbach's alpha ≥0.76; baseline, week 8). VVSymQ(®) scores were more strongly associated with PRO scores that reflect symptoms and symptom impact (the Venous Insufficiency Epidemiological and Economic Study-Quality of Life/Symptoms [VEINES-QOL/Sym] instrument and the Chronic Venous Insufficiency Quality-of-Life Questionnaire [CIVIQ-20]) than with PRO scores that reflect appearance (the Patient Self-Assessment of Appearance of Visible Varicose Veins [PA-V(3)]) or clinician-reported outcome scores (the Clinical-Etiology-Anatomy-Pathophysiology [CEAP] Classification of Venous Disorders and Venous Clinical Severity Score [VCSS]), demonstrating construct validity. Patients reporting that symptoms were "moderately" or "much improved" on the Patient Global Impression of Change (PGIC) anchor (i.e., >97 % of patients) had mean improvements of -6.3 VVSymQ(®) points, while a cumulative distribution curve showed that 50 % of patients improved by ≥-5.8 points; thus, a score change of approximately -6 demonstrated a clinically meaningful change in this study. The clinically meaningful change in the VVSymQ(®) score was greater in patients with a greater baseline VVSymQ(®) symptom burden, and the VVSymQ(®) instrument captured clinically meaningful treatment benefit even in patients with a low baseline symptom burden.
The 5-item VVSymQ(®) instrument is a brief, psychometrically sound, useful tool for evaluating patient-reported varicose veins symptoms.