Healthcare Use Patterns for High Volume Musculoskeletal Shoulder Disorders: A Longitudinal Cohort from the US Military Health System.

Background: Shoulder injuries are a prevalent form of musculoskeletal disorders and common reason to seek healthcare. Health system level care utilization patterns for shoulder disorders are unknown. Accordingly, we described the frequency and timing of diagnostic imaging and treatment for a new episode of shoulder pain and determine usage variations across common diagnostic subgroups, military, and private sector care clinics. Methods: A retrospective cohort of US Military Health System beneficiaries (n = 456,241) classified into 1) non-specific shoulder diagnosis only, 2) rotator cuff/sub-acromial pain, 3) acromioclavicular (AC joint) dysfunction, 4) shoulder instability/dislocation, 5) hypomobility/adhesive capsulitis, 6) osteoarthrosis, and 7) multiple diagnoses. Outcomes were healthcare use encounters within the first three months of the index visit classified into diagnostic imaging, pharmacological, and non-pharmacological treatments. Results: The mean age of the cohort was 41 years old (SD 13). A majority of the cohort never received diagnostic imaging (76.7%). Advanced imaging was common for the multiple diagnoses group (53.6% of all advanced imaging). NSAIDS was the most common pharmacological treatment with 10.4% receiving at least one prescription, and physical therapy was the most common nonpharmacologic treatment received by 31% of the cohort. There was lower physical therapy and active treatment use and higher MRI or X-ray use for the same diagnostic group when care was initiated in a civilian clinic. Patients with rotator cuff disorders, multiple shoulder diagnoses, and hypomobility disorders were likely to have received at least one steroid joint injection if care was initiated in civilian compared to military clinics (28.1% vs 16%; 41.2% vs 32%; and 18.6% vs 13.3%, respectively). Conclusion: Care patterns for high volume shoulder injuries were largely congruent across military and civilian clinics. However, for specific diagnostic groups, use of imaging, steroid injections and physical therapy varied notably between military and civilian clinics.