Abstract
BACKGROUND: Some domains of the questionnaires used to measure symptoms and quality of life (QOL) in patients with advanced cancer seem to measure similar dimensions or constructs, so it would be useful for clinicians to demonstrate the interchangeability of equivalent domains of the questionnaires in measuring the same constructs. OBJECTIVE: This study investigated the reliability and concurrent validity of the Palliative Outcome Scale (POS), the Rotterdam Symptom Checklist (RSCL), and the Brief Pain Inventory (BPI), used to measure symptom control in patients with advanced cancer. DESIGN: This was an evaluative study. SETTING/SUBJECTS: Subjects were patients with advanced cancer attended by Spanish primary care physicians. MEASUREMENTS: Secondary analysis was performed of 117 outpatients who completed the POS, BPI, and RSCL at two different times, with an interval of 7 to 10 days. Bland and Altman analyses and plot, repeatability coefficient, as well as Spearman correlations were carried out. RESULTS: There were 117 included patients. Mean age was 69.4 (11.5) years, gender was 60% male, 37.6% completed only elementary school, diagnoses were mainly digestive and lung cancer, with a low functional rate and presence of oncologic pain. First and second questionnaire rounds showed significant correlations and agreement. Agreement was shown between pain intensity of BPI and pain and physical scales of RSCL, and between physical symptoms of RSCL and of POS, with significant correlations in equivalent dimensions. CONCLUSION: BPI, POS, and RSCL have shown adequate reliability and moderate concurrent validity among them.