Validation of the parent's postoperative pain measure with an age-appropriate reference pain scale for children 2-12 years old during a 14-day recovery after tonsillectomy: A prospective cohort study

Background Adenotonsillectomy is associated with severe postoperative pain. The parent's postoperative pain measure (PPPM), a 15-item instrument to measure a child's pain at home, has been validated with a seven-point faces scale in children 7-12 years and with the parents' global report of pain in children 2-6 years. Aims Our primary objective was to validate the PPPM with a recommended age-appropriate pain scale in children 2-12 years after adenotonsillectomy. Our secondary objective was to reduce the PPPM components and validate this reduced PPPM. Methods We recruited 319 children out of the 563 adenotonsillectomies performed between December 19, 2017, and December 18, 2018. Parents recorded administration of analgesics and their child's pain scores twice daily for 14 days: PPPM for all children and either the face, legs, arms, crying, consolability (FLACC) pain scale for children 2-3 years or the faces pain scale-revised (FPS-R) for children 4-12 years. In addition, parents recorded analgesics. Results Among the 354 eligible children, 9% of parents declined. 252 (79%) families submitted pain diaries. The median age was 2.9 [2.5-3.3] years for FLACC (n = 114) and 5.6 [4.5-7.2] years for FPS-R (n = 138). Across the 14-day recovery period, Cronbach's alpha for PPPM was 0.77 to 0.87. Generalized linear mixed models evaluated the association between PPPM and reference pain scales after adjustment for potential confounders. Time of day and postoperative days were included as predictors in the models. PPPM was strongly associated with FLACC and FPS-R (beta coefficient = 0.4; p < 0.0001). The association decreased over time, and the reduction was more significant for FPS-R than FLACC (beta coefficient = -0.13 vs. -0.04, respectively; p < 0.0001). There was a positive association between PPPM and the use of analgesics. A reduction analysis eliminated items from the original PPPM: four for FLACC and five for FPS-R, suggesting age-related differences. The reduced PPPM instruments achieved similar associations with their respective reference pain scales (beta coefficient = 0.5; p < 0.0001). Conclusions This study extends previous work by validating the PPPM in children as young as 2 years with a recommended age-appropriate pain scale over 14-day convalescence after adenotonsillectomy. The reduced PPPM instruments differed in the two age groups. Future studies might explore these age-appropriate reduced PPPM instruments to assess pain at home following adenotonsillectomy.