Pain rating schema: three distinct subgroups of individuals emerge when rating mild, moderate, and severe pain

Abstract

Laura A Frey-Law,1 Jennifer E Lee,2,3 Alex M Wittry,4 Myles Melyon5 1Department of Physical Therapy and Rehabilitation Science, The University of Iowa, Iowa City, IA, USA; 2Mount Mercy University, Department of Psychology, Cedar Rapids, IA, USA; ³College of Nursing, The University of Iowa, 4Department of Emergency Medicine, The University of Iowa Hospitals and Clinics, Iowa City, IA, USA; 5Midwestern University, Glendale, AZ, USA Background: While the validity of pain assessment has been well documented, the underlying schema (ie, organized, preconceived ideas) of how individuals interpret numerical pain ratings is not well understood. This study's objectives were to examine numerical pain intensity ratings, from (0 to 10 cm on the visual analog scale [VAS]) across multiple severities of commonly experienced acute pain conditions to determine whether the ratings differed between these pain conditions and/or between individuals. Methods: A community sample (N=365, 66% female) rated their anticipated pain intensity (VAS) for threshold, mild, moderate, severe, and tolerance level, using several common pain conditions: headache, toothache, joint injury, delayed-onset muscle soreness, burns, and “general pain.” Results: Cluster analysis revealed three subgroups of individuals, suggesting three types of underlying pain rating schema: 1) Low Rating subgroup (low VAS pain intensity ratings across all the pain severity categories); 2) Low/High Rating subgroup (low VAS pain intensity rating for mild, but high VAS pain intensity rating for severe pain); and 3) High Rating subgroup (high VAS pain intensity ratings across all the pain severity categories). Overall, differences between pain conditions were small: muscle soreness pain intensity was consistently rated lower than the other pain types across severities. The highest pain ratings varied between joint injury and general pain, depending on severity level. No effects of sex or current experience of pain were noted. Conclusion: The results indicate that: 1) three distinct pain schemas were present in this community-based sample, indicating significant variation in how pain scales are utilized and/or interpreted between clusters of individuals; 2) pain ratings vary by condition, but these differences are minor; and 3) pain rating schemas are not significantly different between males and females or between individuals with and without current pain. Keywords: VAS, muscle soreness, headache, toothache, joint pain