In many patient sub-populations prevalent in the VA health care system, shoulder-related dysfunction is a common and debilitating health problem. Evidence-based treatment of shoulder problems is needed. Fundamental to the success of such studies is the existence of a reliable and valid scale to measure shoulder functioning. However, for wide applicability, it is critical that such a scale have the sensitivity to capture small, but clinically important changes in functioning without imposing unreasonable response burden on patients.
The flexi-level scale consists of three testlets (subsets of items) targeted toward high, medium, and low shoulder functioning. Patients are directed, based on their response to an initial screening item, to the level-specific testlet designed to most precisely measure their shoulder functioning. The adaptive approach is more efficient than traditional scaling, yielding maximum efficiency with minimum response burden.
Both standard and modern psychometric methodology are being used. A developmental form of the survey was administered to almost 400 persons at the Houston VAMC, Texas Orthopedic Hospital, and Harris County Hospital District. Once these data were collected, items were Rasch-calibrated. Three testlets that target high, medium, and low shoulder functioning were extracted. We identified a screening item to be used in channeling respondents to the most appropriate testlet and then equated the testlets to a single mathematical scale.
In a second phase of the study, we are evaluating the psychometric properties of the scale. Two hundred persons were recruited to complete the flexilevel scale at baseline, 1 month, 2 month, 3 month. To evaluate test-retest reliability, the first one hundred patients recruited were also asked to complete a second survey within 48 hours of completing the survey at baseline.
In conducting focus group interviews, we noted that patients frequently reported experiencing depression that they associated with pain medication and the limits their shoulder problems placed on their lives. We have learned that shoulder dysfunction can hinder a person's ability to do many common tasks (e.g., drink out of a cup, dress, reach into the backseat of a car). These tasks translate into individual items for the scaling of shoulder function. Preliminary analysis of the developmental form of the survey indicates that the scale has excellent reliability.
The flexi-level scale will have the measurement precision to track individual change in outcome over time making it an important tool both in clinical trials and the assessment of individual veterans in the clinic.
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