Responsiveness of the shoulder pain and disability index in patients with adhesive capsulitis.

Einar Kristian Tveitå,Ole Marius Ekeberg,Erik Bautz-Holter,Niels Gunnar Juel

doi:10.1186/1471-2474-9-161

Einar Kristian Tveitå, Ole Marius Ekeberg + Show 2 more

Open Access

https://doi.org/10.1186/1471-2474-9-161

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Abstract

BackgroundInstruments designed to measure the subjective impact of painful shoulder conditions have become essential in shoulder research. The Shoulder Pain and Disability Index (SPADI) is one of the most extensively used scales of this type. The objective of this study was to investigate reproducibility and responsiveness of the SPADI in patients with adhesive capsulitis.MethodsSPADI test-retest reproducibility was estimated by the "intraclass correlation coefficient" (ICC) and the "smallest detectable difference" (SDD). Responsiveness was assessed by exploring baseline and follow-up data recorded in a recently reported clinical trial regarding hydrodilatation and corticosteroid injections in 76 patients with adhesive capsulitis. "Standardized response mean" (SRM) and "reliable change proportion" (RCP) for SPADI were compared with corresponding figures for shoulder range-of-motion (ROM). The relationship between SPADI and ROM change scores was investigated through correlation and linear regression analyses.ResultsResults for test-retest reproducibility indicated a smallest detectable difference of 17 points on the 0–100 scale, and an intraclass correlation coefficient of 0.89. The SPADI was generally more responsive than ROM. Weak to moderately strong associations were identified between SPADI and ROM change scores. According to the regression model, the three variables baseline SPADI, baseline active ROM and change in active ROM together explained 60% of the variance in SPADI improvement.ConclusionThis study supports the use of SPADI as an outcome measure in similar settings.

Highlights

Instruments designed to measure the subjective impact of painful shoulder conditions have become essential in shoulder research
This study supports the use of Shoulder Pain and Disability Index (SPADI) as an outcome measure in similar settings
Distributions of SPADI subscale and total scores on both occasions approximate normal distributions according to plots

Summary

Introduction

Instruments designed to measure the subjective impact of painful shoulder conditions have become essential in shoulder research. The SPADI change score was compared to the measure of global change, where the patient had rated his shoulder problem as "cured", "improved", "the same" or "worse" compared to his baseline examination Based on these comparisons, the authors stated that "the SPADIΔ (baseline – follow-up) discriminated accurately between subjects who improved versus those who stayed the same or worsened" [3]. The authors stated that "the SPADIΔ (baseline – follow-up) discriminated accurately between subjects who improved versus those who stayed the same or worsened" [3] This statement regarding SPADI responsiveness can hardly be expected to apply to settings in clinical trials where more traditional designs are used when gathering follow-up scores. Retrospective methods of computing responsiveness yield little information about the ability of an instrument to detect treatment effects, and they should not be used as a basis for the choice of an instrument for applications to clinical trials [4,5]

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