title: An observational study of agreement between percentage pain reduction calculated from visual analog or numerical rating scales versus that reported by parturients during labor epidural analgesia.
abstract: BACKGROUND
  This study aimed to determine the level of agreement between calculated percentage pain reduction, derived from visual analog or numerical rating scales, and patient-reported percentage pain reduction in patients having labor epidural analgesia.
  
  
  METHODS
  In a prospective observational study, parturients were asked to rate their pain intensity on a visual analog scale and numerical rating scale, before and 30min after initiation of epidural analgesia. The percentage pain reduction 30min after epidural analgesia was calculated by the formula: 100×(score before epidural analgesia-score 30min after epidural analgesia)/score before epidural analgesia. To evaluate agreement between calculated percentage pain reduction and patient-reported percentage pain reduction, we computed the concordance correlation coefficient and performed Bland-Altman analysis.
  
  
  RESULTS
  Ninety-seven women in labor were enrolled in the study, most of whom were nulliparous, with a singleton fetus and in spontaneous labor. The concordance correlation coefficient with patient-reported percentage pain reduction was 0.76 (95% CI 0.6 to 0.8) and 0.77 (95% CI 0.6 to 0.8) for the visual analog and numerical rating scale, respectively. The Bland-Altman mean difference between calculated percentage pain reduction and patient-reported percentage pain reduction for the visual analog and numerical rating scales was -2.0% (limits of agreement at 29.8%) and 0 (limits of agreement at 28.2%), respectively.
  
  
  CONCLUSIONS
  The agreement between calculated percentage pain reduction from a visual analog or numerical rating scale and patient-reported percentage pain reduction in the context of labor epidural analgesia was moderate. The difference could range up to 30%. Patient-reported percentage pain reduction has advantages as a measurement tool for assessing pain management for childbirth but differences compared with other assessment methods should be taken into account.
authors.affiliation: Service d'Anesthésie, CHU Louis Mourier, AP-HP, Université Paris 7, Paris, France.
authors.forename: E
authors.initials: E
authors.lastname: Pratici
authors.affiliation: Service d'Anesthésie, CHU Louis Mourier, AP-HP, Université Paris 7, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Nebout
authors.affiliation: Service d'Anesthésie, CHU Louis Mourier, AP-HP, Université Paris 7, Paris, France.
authors.forename: N
authors.initials: N
authors.lastname: Merbai
authors.affiliation: Service d'Anesthésie, CHU Louis Mourier, AP-HP, Université Paris 7, Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Filippova
authors.affiliation: Unité de Recherche Clinique - GH HUPNVS - Site Louis Mourier, AP-HP, Université Paris, Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Hajage
authors.affiliation: Service d'Anesthésie, CHU Louis Mourier, AP-HP, Université Paris 7, Paris, France; Université Paris Diderot, Sorbonne Paris Cité, EA Recherche Clinique Coordonnée Ville-Hôpital, Méthodologies et Société (REMES), Paris, France. Electronic address: hawa.keita@aphp.fr.
authors.forename: H
authors.initials: H
authors.lastname: Keita
mesh_terms: D000328:Adult; D015360:Analgesia, Epidural / Q000379:methods*; D016362:Analgesia, Obstetrical / Q000379:methods*; D036861:Delivery, Obstetric; D005260:Female; D006801:Humans; D007743:Labor, Obstetric; D010147:Pain Measurement / Q000379:methods*; D011247:Pregnancy; D011446:Prospective Studies; D015203:Reproducibility of Results
keywords: Concordance correlation coefficient; Epidural analgesia; Labor pain; Pain scales