Short-Term Variability in Outpatient Pain Intensity Scores in a National Sample of Older Veterans with Chronic Pain

Abstract

Objective: The Department of Veterans Affairs (VA) uses the 11-point pain numeric rating scale (NRS) to gather pain intensity information from veterans at outpatient appointments. Yet, little is known about how NRS scores may vary over time within individuals; NRS variability may have important ramifications for treatment planning. Our main objective was to describe variability in NRS scores within a 1-month timeframe, as obtained during routine outpatient care in older patients with chronic pain treated in VA hospitals. A secondary objective was to explore for patient characteristics associated with within-month NRS score variability. Design: Retrospective cohort study. Subjects: National sample of veterans 65 years or older seen in VA in 2010 who had multiple elevated NRS scores indicating chronic pain. Methods: VA datasets were used to identify the sample and demographic and clinical variables including NRS scores. For the main analysis, we identified subjects with two or more NRS scores obtained in each of two or more months in a 12-month period; we examined ranges in NRS scores across the first two qualifying months. Results: Among 4,336 individuals in the main analysis cohort, the mean and median of the average NRS score range across the 2 months were 2.7 and 2.5, respectively. In multivariable models, main significant predictors of within-month NRS score variability were baseline pain intensity, overall medical comorbidity, and being divorced/separated. Conclusions: The majority of patients in the sample had clinically meaningful variation in pain scores within a given month. This finding highlights the need for clinicians and their patients to consider multiple NRS scores when making chronic pain treatment decisions.