Quantitative assessment of posture in healthy controls and patients with Parkinson's disease

Introduction: A stooped posture is a main clinical feature of Parkinson's disease (PD). The assessment of posture is important to measure treatment effects. The aim of this study was to investigate the reliability of a standardized postural rating tool, to calculate minimal detectable change scores and to assess the role of gender and age. Methods: Two independent raters assessed total camptocormia (TCC), upper camptocormia (UCC) and Pisa angles of 192 PD patients and 78 healthy controls (HC) with the free NeuroPostureApp (c)(http://www. neuroimaging.uni-kiel.de/NeuroPostureApp). Reliabilities and linear models were calculated for different effects. Three subgroups were defined based on two thresholds (mean+2SD of HC and PD): A) normal, B) presumed stooped/lateral bended posture and C) postural disorder. Results: Intraclass correlation coefficients ranged between 0.71 and 0.95 for the interrater and test-retest reliability of the three angles. The minimal detectable change values in the PD patients were 3.7 degrees, 6.7 degrees and 2.1 degrees for the TCC, UCC and Pisa angles, respectively. Men had a more stooped posture than women (p < 0.05). Patients with PD had a worse posture than HC (p < 0.001) in all three angles. For the TCC angle, 39.1% of the patients had a normal posture ( 17.4 degrees), 47.9% a presumed stooped posture ( 30.2 degrees) and 6.3 degrees had camptocormia ( 30.2 degrees). Conclusions: The NeuroPostureApp (c) is reliable. Our results confirmed gender differences and the progression of postural deviation in PD patients with age and empirically support the >= 30 degrees TCC angle as a defining criterium for camptocormia. Diagnostic criteria for UCC and Pisa syndrome should be further explored in future studies.