To What Degree do Shoulder Outcome Instruments Reflect Patients’ Psychologic Distress? CORR
This is an important question – if we are using an instrument to measure the status of our patients, we need to understand what all is being measured by the measurement.
The authors correlated measures of psychological distress, depression and anxiety with commonly used measures of shoulder function in 119 patients with chronic shoulder problems. The authors found that the Constant-Murley score (which includes assessments of pain, function, range of motion and strength) correlated highly with range of motion, pain and strength and less with psychological factors – not surprising. The Simple Shoulder Test and DASH (which are patient self-assessments of comfort and function without measurements of range of motion or strength) were more heavily influenced by psychological factors. The tempting conclusion is that the differences observed are related to the inclusion of range of motion and strength measurements in the Constant score which overwhelm the effect of the psychologic factors. The authors could have examined this possibility by repeating the analysis of the Constant score without the strength and range of motion components.
Shoulder conditions and psychological conditions are each common, so it is expected that many individuals will have both, even in the absence of a cause-effect relationship. Furthermore, it is expected that an individual with a chronic shoulder issue will experience distress as a result. Finally, psychological distress (for example about job related issues) would be expected to intensify the impact of a shoulder condition on an individual’s assessment of his/her shoulder function.
Patients often ask, “how much of my problem is in my head and how much is in my shoulder?”. Our answer is “we can’t know, but our task is to consider you as a whole person – shoulder and head included”. As the authors of this study might suggest, individuals with substantial psychological distress may benefit from management of this component along with or even before management of the shoulder issue.
As for the relative value (benefit/cost) of different ‘outcome instruments’, we favor the SST because it provides a quick and inexpensive patient self-evaluation of shoulder comfort and function. Since our goal is to improve self-assessed comfort and function, we can measure our success (whether by non-operative or non-operative means) in terms of the change in SST score. The Constant score and the DASH are more expensive to administer and to record; this study does not provide evidence that either of these generates data that is more useful than the SST.
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