Comparative study of physician applied and patient reported Constant Scores utilising bathroom scales to derive force measurements

Completed Research - Long Term Projects

Comparative study of physician applied and patient reported Constant Scores utilising bathroom scales to derive force measurements

Background

The Constant Score is a widely used shoulder-specific scoring system. Devised by Christopher Constant in 1987, this functional assessment score was conceived as a system of assessing the overall value, or functional state, of a normal, diseased or treated shoulder.

In 1992, the European Shoulder and Elbow Society mandated the use of the Constant Score in all peer-reviewed papers, making it the most widely used shoulder evaluation instrument in Europe (and around the world). It is reliable and reproducible, providing a subjective and objective measure of patient symptoms and strength. It also provides an important measure for patient follow up and has the potential to highlight specific patient concerns.

Rationale

Administration of the Constant Score can be time consuming. A “remote” method of administering the Constant Score would allow easy patient assessment pre- and post-surgery. Patients would be able to complete the score at home and track their own progress. In addition to this, the strength component of the Constant Score has traditionally been measured using an isometric dynamometer which allows measurement of force exerted during 3-second periods. Dynamometers can be expensive meaning that some investigators and clinicians with limited budgets experience difficulties acquiring this device.

Objectives

The objectives of this study were to evaluate a remote (patient-led) administration of the Constant Score and evaluate the use of bathroom scales to measure the strength component of the test and compare results with those obtained by clinician-led administration.

Design

This study was undertaken at the orthopaedic outpatient clinic of Royal North Shore Hospital.

Inclusion criterion was broad – anyone between the ages 20 – 70 years of age presenting with a shoulder problem. Exclusion criterion was also broad – only those who were less than 6 month post-operative were excluded. After obtaining informed consent, 101 patients were sent a modified version of the Constant Score questionnaire by email which they completed at home and returned to the investigators. As part of this questionnaire they were given instructions (with photographs) on how to calibrate their own bathroom scales and measure their shoulder strength. Patients then were administered the Constant Score and had their strength measured in Clinic at their follow up appointment.

No special follow up appointments were made, and there was no intervention or change in patient management.

Inclusion Criteria

Age 20 – 70 years
Willingness to give written informed consent and willingness to participate in and comply with the Study.

Exclusion Criteria

Minimum 6 months post-operative period

Ethics and Governance

Approved by Northern Sydney Local Health District Human Research Ethics Committee to be undertaken at Royal North Shore Hospital. HREC reference LNR/13/HAWKE/317.

Results

101 patients were included in the final analysis. The evaluation of concurrent validity resulted in a Pearson’s Correlation coefficient of 0,929 (p=0.01), suggesting a very strong correlation between the means of both strength measurements. This result suggests that this patient-led administration of the Constant Score and the use of a bathroom scale are suitable alternatives to physician-led assessment of shoulder strength and function.

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