Minimal important difference and patient acceptable symptom state for the Numerical Rating Scale (NRS) for pain and the Patient-Rated Wrist/Hand Evaluation (PRWHE) for patients with osteoarthritis at the base of thumb

Susanna Stjernberg-Salmela; Teemu Karjalainen; Joona Juurakko; Pirjo Toivonen; Eero Waris; Simo Taimela; Clare L Ardern; Teppo L N Järvinen; Jarkko Jokihaara

doi:10.1186/s12874-022-01600-1

Minimal important difference and patient acceptable symptom state for the Numerical Rating Scale (NRS) for pain and the Patient-Rated Wrist/Hand Evaluation (PRWHE) for patients with osteoarthritis at the base of thumb

BMC Med Res Methodol. 2022 Apr 29;22(1):127. doi: 10.1186/s12874-022-01600-1.

Authors

Susanna Stjernberg-Salmela^{1

2}, Teemu Karjalainen^{2

3}, Joona Juurakko⁴, Pirjo Toivonen², Eero Waris¹, Simo Taimela^{2

5}, Clare L Ardern^{2

6}, Teppo L N Järvinen^{2

5}, Jarkko Jokihaara^{7

8

9}

Affiliations

¹ Department of Hand Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
² Finnish Centre of Evidence-Based Orthopedics (FICEBO), University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
³ Central Finland Central Hospital, Jyväskylä, Finland.
⁴ Central Finland Health Care District, Jyväskylä, Finland.
⁵ Department of Orthopaedics and Traumatology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
⁶ Department of Family Practice, University of British Columbia, Vancouver, Canada.
⁷ Finnish Centre of Evidence-Based Orthopedics (FICEBO), University of Helsinki and Helsinki University Hospital, Helsinki, Finland. [email protected].
⁸ Department of Hand and Microsurgery, Tampere University Hospital, Kuntokatu 2, 33520, Tampere, Finland. [email protected].
⁹ Faculty of Medicine and Health Technology, Tampere University, Arvo Ylpon katu 6, 33520, Tampere, Finland. [email protected].

Abstract

Background: The Numerical Rating Scale (NRS) and Patient-rated wrist/hand evaluation (PRWHE) are patient-reported outcomes frequently used for evaluating pain and function of the wrist and hand. The aim of this study was to determine thresholds for minimal important difference (MID) and patient acceptable symptom state (PASS) for NRS pain and PRWHE instruments in patients with base of thumb osteoarthritis.

Methods: Fifty-two patients with symptomatic base of thumb osteoarthritis wore a splint for six weeks before undergoing trapeziectomy. NRS pain (0 to 10) and PRWHE (0 to 100) were collected at the time of recruitment (baseline), after splint immobilization prior to surgery, and at 3, 6, 9 and 12 months after surgery. Four anchor-based methods were used to determine MID for NRS pain and PRWHE: the receiver operating characteristics (ROC) curve, the mean difference of change (MDC), the mean change (MC) and the predictive modelling methods. Two approaches were used to determine PASS for NRS pain and PRWHE: the 75^th percentile and the ROC curve methods. The anchor question for MID was the change perceived by the patient compared with baseline; the anchor question for PASS was whether the patient would be satisfied if the condition were to stay similar. The correlation between the transition anchor at baseline and the outcome at all time points combined was calculated using the Spearman's rho analysis.

Results: The MID for NRS pain was 2.5 using the ROC curve method, 2.0 using the MDC method, 2.8 using the MC method, and 2.5 using the predictive modelling method. The corresponding MIDs for PRWHE were 22, 24, 10, and 20. The PASS values for NRS pain and PRWHE were 2.5 and 30 using the ROC curve method, and 2.0 and 22 using the 75th percentile method, respectively. The area under curve (AUC) analyses showed excellent discrimination for all measures.

Conclusion: We found credible MID estimates for NRS and PRWHE (including its subscales), although the MID estimates varied depending on the method used. The estimates were 20-30% of the range of scores of the instruments. The cut-offs for MID and PASS showed good or excellent discrimination, lending support for their use in future studies.

Trial registration: This clinimetrics study was approved by the Helsinki University ethical review board (HUS1525/2017).

Keywords: Hand; Minimal important difference; Osteoarthritis; Patient acceptable symptom state; Patient reported outcome measures; Treatment outcome; Wrist.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Disability Evaluation
Humans
Osteoarthritis* / diagnosis
Osteoarthritis* / surgery
Pain / diagnosis
Pain / etiology
Thumb*
Wrist