ABSTRACT
BACKGROUND: Natural history of disease refers to the progression of a disease process in an individual over time, in the absence of treatment. Understanding natural history of tendinopathies is key for clinicians to make accurate prognostic predictions and design effective intervention studies. OBJECTIVE: To quantify the natural history of the main tendinopathies regarding pain and function and to compare outcomes between untreated individuals and those receiving treatment. METHODS: A systematic literature search was conducted until February 2023, across PubMed, Cochrane, Embase and Scopus databases. Selection criteria included randomized controlled trials (RCTs) with a "wait-and-see" group and cohort studies with ≥3 months of follow-up reporting on pain and function-related outcomes. Standardized mean differences (SMDs) of "wait-and-see" groups were pooled using a random-effects inverse-variance model. Risk of bias was assessed using Cochrane Risk-of-Bias (RoB2), and quality of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach. RESULTS: Six RCTs were included, encompassing 518 subjects with tendinopathy. Pooled results demonstrated significant pain (SMD = 0.30, 95%CI: 0.19-0.41) and physical function improvement (SMD = 0.38, 95%CI: 0.28-0.48). These estimates remained consistent regardless of age or follow-up duration. In rotator cuff tendinopathy, untreated individuals improved but did not fully recover at one year, with similar outcomes to other interventions (e.g., surgery). Subjects with lateral elbow, patellar and achilles tendinopathies when untreated, did not fully resolve symptoms within 12-16 weeks. CONCLUSIONS: This review provides limited conclusions about natural history of tendinopathies. Future studies should incorporate true no-intervention groups to accurately reflect tendinopathy's natural progression.
