Study design: Cross-sectional.
Objectives: This study examined the baseline relationship of pain intensity, physical impairment, and pain-related fear to shoulder function.
Background: There is no consensus regarding the influence psychological variable have on function and recovery in individuals with shoulder pathologies. While pain-related fear has been shown to predict disability for patients with low-back and cervical pain, this relationship has not been consistently reported for patients with shoulder pain.
Methods and measures: One hundred forty-two subjects (78 male, 64 female; mean age, 41.4 years) with nonoperative unilateral shoulder disorders were identified from a clinical database of impairment and outcome measures.Demographic information, duration of symptoms, mechanism of injury, pain intensity, pain-related fear, and range-of-motion (ROM) measures were collected. Self-report of function was measured with the Shoulder Pain and Disability Index (SPADI). Hierarchical regression analysis determined the proportions of explained variance in function.
Results: Demographic variables (duration of symptoms, sex, age, and mechanism of injury) collectively contributed approximately 9% (P=.003) of the variance in function scores. Average pain intensity and flexion ROM contributed an additional 22% (P<.001) of the variance, and Tampa Scale of Kinesiophobia (TSK-11) scores contributed an additional 3% (P<.001). In the final parsimonious model, presence of symptoms longer than 3 months (beta=.23, P=.003), pain intensity (beta=.25, P=.002), shoulder flexion ROM index (beta=-.35, P=.001), and kinesiophobia (beta=.17, P=.026) explained 33% of the variance in SPADI function score (P<.001).
Conclusions: Presence of symptoms longer than 3 months, average pain intensity, flexion ROM index (strongest contributor in multivariate model), and fear-of-pain scores all contributed to baseline shoulder function. The immediate clinical relevance of these findings is unclear but they do provide direction for prospective studies.