Patient processes for attributing a numerical rating to postoperative pain intensity after total knee joint replacement surgery: a qualitative study.

Abstract

BACKGROUND: An 11-point numerical rating scale (NRS) is commonly used after surgery as an unidimensional measure of pain intensity, however little is known about patients' approach to and application of the scale. This qualitative study examined the processes patients use to select and communicate a number representative of their postoperative pain intensity. METHODS: This qualitative study has an exploratory, descriptive design using semi-structured interviews conducted 24 hours after total knee joint replacement (TKJR) surgery. Open-ended questions and validated pain measurement tools were used. Patients (n=59) were selected purposively to represent age and sex: males (n=24; aged ≤64yr=10; ≥65yr=14) and females (n=35; ages ≤64yr=14; ≥65yr=21). Transcripts were coded and analysed using both content and thematic analyses. RESULTS: Two key processes emerged. 1. Calibration involved using the scale's structure and personal experience as a fram of reference to locate pain intensity and define anchor points. 2. Score adjustment identified dimensions other than intensity, that patients incorporate into the calibration process to manage the dynamic nature of their pain as well as to navigate the routines and uncertainties of the clinical environment necessary to achieve analgesia. CONCLUSION: Our findings suggest that numerical pain ratings reported by patients represent a complex interplay of personal and contextual factors, rather than just their current pain intensity and the validity of using them as the basis for pain management decisions is questionable. Rather the NRS should be considered a starting point for comprehensive clinical assessment and underscores the need for a more systematic, standardised application of the NRS clinically.