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Minimally important differences for Patient Reported Outcomes Measurement Information System pain interference for individuals with back pain

Authors Amtmann D, Kim J, Chung H, Askew R, Park R, Cook K

Received 27 August 2015

Accepted for publication 19 January 2016

Published 27 April 2016 Volume 2016:9 Pages 251—255


Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Kerui Gong

Peer reviewer comments 3

Editor who approved publication: Dr Michael Schatman

Dagmar Amtmann,1 Jiseon Kim,1 Hyewon Chung,2 Robert L Askew,3 Ryoungsun Park,4 Karon F Cook5

1Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA; 2Department of Education, Chungnam National University, Daejeon, Republic of Korea; 3Department of Psychology, Stetson University, Deland, FL, USA; 4Theoretical and Behavioral Foundations Division, Wayne State University, Detroit, MI, USA; 5Department of Medical Social Science, Northwestern University, Chicago, IL, USA

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.
Conclusion: 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.

Keywords: minimally important differences, pain interference, back pain, Patient Reported Outcomes Measurement Information System, responsiveness, PROMIS

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