The Minimally Important Difference for the Fatigue Visual Analog Scale in Patients with Rheumatoid Arthritis Followed in an Academic Clinical Practice

Abstract

Introduction Fatigue is a common symptom in RA and used as an outcome measure in RA clinical trials. We studied a large academic clinical practice to estimate the minimally important difference (MID) for a fatigue visual analog scale using patient-reported anchors (fatigue, pain and overall health). Methods RA patients (N=307) had clinic visits at 2 time points at a median of 5.9 months apart. They completed fatigue visual analog scale (VAS; 0–10) and retrospective anchor items, “How would you describe your overall fatigue/pain/overall health since the last visit?” Much worsened, Somewhat worsened, Same, Somewhat better, or Much better. The fatigue anchor was used for primary analysis and the pain/ overall health anchors for sensitivity analyses. The minimally changed group was defined by those reporting they were somewhat better or somewhat worsened. Results The mean (SD) age was 59.4 (13.2) years, disease duration was 14.1 (11.5) years, and 83% of patients were women. The baseline mean (SD) HAQ-DI score was 0.84 (0.75). The baseline fatigue VAS score was 4.2 (2.9) and at follow up was 4.3 (2.8) (mean change of −0.07 [2.5], p=NS). The fatigue change score (0–10 scale) for somewhat better and somewhat worsened for fatigue anchor averaged −1.12 and 1.26, respectively. Using pain anchor, the fatigue changed score for somewhat better and somewhat worsened averaged −0.87 and 1.13 and using global anchor, the fatigue changed score for somewhat better and somewhat worsened averaged −0.82 and 1.17, respectively. Effect size (ES) estimates using 3 anchors were small for somewhat better (range: 0.27 to 0.39) and somewhat worsened (range: 0.40 to 0.44) groups but larger than the no-change group (range: 0.03 to 0.08). Conclusions The MID for fatigue VAS is between −0.82 to −1.12 for improvement and 1.13 to 1.26 for worsening on 0–10 scale in a large RA clinical practice and similar to that seen in RA clinical trials. This information can aid in interpreting fatigue VAS in day-to-day care in clinical practice.

Fast-Pitch Softball Pitchers Experience a Significant Increase in Pain and Fatigue During a Single High School Season

“…The players experienced an increase in VAS fatigue 1.17 to 2.83 during the games. The published MCID for VAS fatigue is 0.82 to 1.13 [13]. Finally, the players experienced an increase in exertion with Borg scale of 1.82 during the game at the end of the season, and the MCID for Borg scale is 1 [19] showing our results were statistically and clinically significant.…”

Association of Improvement in Pain With Therapeutic Response as Determined by Individual Improvement Criteria in Patients With Rheumatoid Arthritis

“…Studies using statistically based measures to determine values that exceed random variation, such as SDD or reliable change index, consistently report higher values than those that report MCID. This is best illustrated by a study of fatigue in patients with RA that reported both MCID and reliable change index 7. The MCID for improvement in fatigue in this study was 0.82 to 1.12, while the reliable change index was 3.47.…”

“…The goal of MCID assessments is to identify the smallest change perceived as beneficial by patients 5, whereas the d crit method is based on the premise that significant individual responses should, at minimum, result in changes that exceed within‐subject, measurement‐associated variability over periods of time relevant to a clinical setting 4. In this respect, the d crit method is similar to assessments of the smallest detectable difference (SDD) 6 or the reliable change index 7. However, these latter assessments are usually based on reliability constants derived from measurements made over a short period of time, rather than over a period of months to a year, a time frame that is more relevant to assessment of RA.…”

Certolizumab pegol plus methotrexate 5-year results from the rheumatoid arthritis prevention of structural damage (RAPID) 2 randomized controlled trial and long-term extension in rheumatoid arthritis patients

“…Fatigue (VAS) [7] and short-form-36 (SF-36) [8] were assessed at baseline, weeks 36, 48, and 76, and then every 24 weeks throughout the OLE. Continuous measures are reported as absolute values or mean changes from RCT baseline.…”