Validation of numerical cut points for mild, moderate, and severe pain across key subgroups of adults with burn injury in a multicenter cohort study: A Burn Model System investigation.

Abstract

The optimal numerical cut points for mild, moderate, and severe burn pain have previously been reported from a single center. Average burn pain can be categorized as mild (0-2), moderate (3-5), and severe (6-10). These findings inform clinical responses to pain scores and benchmarking for research initiatives. To validate these cut points with a larger, more diverse cohort, we aimed to identify average pain intensity rating scores for mild, moderate, and severe using the Patient Reported Outcome Measures Pain Interference (PROMIS-PI) short form. Average 11-point pain intensity numerical rating scale (NRS) scores (0-10) and custom PROMIS-PI short forms were administered to adults with burn injury treated at 5 centers across the US at hospital discharge (baseline) and 6, 12, 24 months and 5 years post-injury. To identify pain intensity scores that best represent mild, moderate, and severe pain, F value statistics associated with multiple ANOVA comparisons for mean pain interference scores by various pain intensity cut points were computed. Based on previous research, 6 possible cut points (CP) were compared: CP 3,6; 3,7; 4,6; 4,7; 2,5; and 3,5. Cut points in subgroup populations were also examined. The optimal cut points were those with the highest ANOVA F statistics. Data from 1283 participants (58 % male, 79 % White, 22 % Hispanic, mean age 46 years) with NRS pain intensity and PROMIS-PI scores at one or more study timepoints were analyzed. The optimal classification for mild, moderate, and severe pain was CP 2,5 at all timepoints for most adult participants. Sub-analyses were performed based on participant sex, race, ethnicity, self-reported preinjury alcohol use, and site of initial hospitalization. This study confirms that for most adults with burn injury within the US, burn intensity ratings of mild (0-2), moderate (3-5), and severe (6-10) are appropriate. These findings support previous findings and continue to advance our understanding of burn pain and pain intensity reporting while providing clinicians and researchers with an objective measure that can be used for screening, treatment, quality improvement, and research.