title: Minimally important differences for Patient Reported Outcomes Measurement Information System pain interference for individuals with back pain.
abstract: BACKGROUND
  The minimally important difference (MID) refers to the smallest change that is sufficiently meaningful to carry implications for patients' care. MIDs are necessary to guide the interpretation of scores. This study estimated MID for the Patient Reported Outcomes Measurement Information System (PROMIS) pain interference (PI).
  
  
  METHODS
  Study instruments were administered to 414 people who participated in two studies that included treatment with low back pain (LBP; n=218) or depression (n=196). Participants with LBP received epidural steroid injections and participants with depression received antidepressants, psychotherapy, or both. MIDs were estimated for the changes in LBP. MIDs were included only if a priori criteria were met (ie, sample size ≥10, Spearman correlation ≥0.3 between anchor measures and PROMIS-PI scores, and effect size range =0.2-0.8). The interquartile range (IQR) of MID estimates was calculated.
  
  
  RESULTS
  The IQR ranged from 3.5 to 5.5 points. The lower bound estimate of the IQR (3.5) was greater than mean of standard error of measurement (SEM) both at time 1 (SEM =2.3) and at time 2 (SEM =2.5), indicating that the estimate of MID exceeded measurement error.
  
  
  CONCLUSIONS
  Based on our results, researchers and clinicians using PROMIS-PI can assume that change of 3.5 to 5.5 points in comparisons of mean PROMIS-PI scores of people with LBP can be considered meaningful.
authors.affiliation: Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Amtmann
authors.affiliation: Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA.
authors.forename: Jiseon
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Education, Chungnam National University, Daejeon, Republic of Korea.
authors.forename: Hyewon
authors.initials: H
authors.lastname: Chung
authors.affiliation: Department of Psychology, Stetson University, Deland, FL, USA.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Askew
authors.affiliation: Theoretical and Behavioral Foundations Division, Wayne State University, Detroit, MI, USA.
authors.forename: Ryoungsun
authors.initials: R
authors.lastname: Park
authors.affiliation: Department of Medical Social Science, Northwestern University, Chicago, IL, USA.
authors.forename: Karon F
authors.initials: KF
authors.lastname: Cook
keywords: PROMIS; Patient Reported Outcomes Measurement Information System; back pain; minimally important differences; pain interference; responsiveness