Shoulder pain is the third most common musculoskeletal complaint and many patients have an unfavorable outcome with long-term disability. Only 50% of all new episodes of shoulder pain show complete recovery within 6 months. Little is known about factors that contribute to chronicity of shoulder pain, although such information is needed for the management of patients with acute and sub-acute shoulder pain. The objective of this study was to systematically review the literature for prognostic factors which are potential predictors for either recovery or chronification in patients with acute and sub-acute non-traumatic shoulder pain. This systematic review was reported following the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Two reviewers independently scored the methodological quality of the selected studies. Due to heterogeneity of studies, a best-evidence synthesis of the available prognostic factors was provided. Nine studies met our inclusion criteria and were included in this systematic review. There is strong evidence that high scores on the Shoulder Pain and Disability Index (SPADI), high scores on shoulder pain severity, and a long duration of complaints are factors that contribute to the chronification of shoulder pain. Moderate evidence was found supportive for other prognostic factors that enhance chronification, like being male, being over 55 years of age, having poor general health, having a gradual onset of complaints, a large amount of sick leave, the perception of high job demand, the perception of low social support, and the amount of visits to a health care professional. Also moderate evidence exists regarding factors that contributed to a reduced possibility of chronification: an active treatment policy and not taking medication on regular basis.
This systematic review found evidence that high scores on the SPADI questionnaire, more shoulder pain, and a longer duration of complaints are associated with chronification of shoulder pain. In order to reduce chronification, clinicians can use the International Classification of Functioning based model presented here that could aid their decision-making.