Evidence of internal construct validity of SOC-13 total score, for use in hand therapy

Abstract

Purpose

The objective was to examine whether the 13-item Sense of coherence scale (SOC-13) can be reported as a unidimensional interval-scale metric, when new approaches based on the Rasch model to address local item dependency are applied, and to determine whether an interval-scale scoring can be made available.

Methods

Data were derived from two samples of patients with hand-related disorders (merged n = 915). Rasch analyses of the SOC data were conducted using item-level analysis and a testlet approach.

Results

Initial item-level analysis of the SOC-13 confirmed previous findings of misfit to the Rasch model. In resolving local dependency by constructing three testlets, which corresponded to the three components of the SOC construct, fit to the Rasch model (χ²(df) = 43.11 (27), p = 0.163) and unidimensionality of the SOC-13 could be established. A transformation table was successfully created to convert the SOC-13 raw ordinal score to corresponding Rasch interval-scaled values.

Conclusions

The results of this study indicate that data obtained by the SOC-13 can be regarded as essentially unidimensional, and an interval-scale transformation table of the SOC-13 total scores was developed, for use in clinical practice and research on coping resources in patients with hand-related disorders.

IMPLICATIONS FOR REHABILITATION

• The 13-item Sense of coherence scale (SOC-13) comprises three complexly interrelated components

• To assess coping resources in patients with hand-related disorders, an interval-scale transformation table of the SOC-13 total scores can be used

Keywords:

• Rasch measurement model; patient-reported outcome; sense of coherence; hand therapy; rehabilitation

Acknowledgements

We would like to thank all the patients who participated in the studies and clinicians (nurses, occupational therapists and surgeons) who enrolled the patients.

Disclosure statement

The authors declare that there are no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

The authors disclose receipt of the following financial support for the research, authorship, and/or publication of this article: Study one was supported by the University of Southern Denmark, the Region of Southern Denmark, the Danish Occupational Therapist Association, Bevica. Foundation and Odense University Hospital. Study two was supported by the Region of Southern Denmark. Funding sources did not have any role in the design of this paper.