Exploration of the clinical course and longitudinal correlations in frozen shoulder: The role of autonomic function, central pain processing, and psychological variables. A longitudinal multicenter prospective observational study

•An early improvement that flattens with time in pain and disability is observed.•Altered central pain processing seems not to have a central role in frozen shoulder.•Several longitudinal correlations seem to exist in patients with frozen shoulder.•These longitudinal correlations indicate potential treatment targets.