Reliability and Validity of Nonradiologic Measures of Forward Flexed Posture in Parkinson Disease

Abstract

Objective: To examine the intertester reliability and validity of 5 nonradiologic measures of forward flexed posture in individuals with Parkinson disease (PD).

Design: Cross-sectional observational study.

Setting: University outpatient facility and community centers.

Participants: Individuals (N=28) with PD with Hoehn and Yahr scores of 1 through 4.

Interventions: Not applicable.

Main outcome measures: Occiput to wall status, tragus to wall distance, C7 to wall distance, photographically derived trunk flexion angle, and inclinometric kyphosis measure.

Results: Participants were older adults (mean, 69.7±10.6y) with a 14-month to 15-year (mean, 5.9±3.5y) history of PD. Intertester reliability was excellent for all measures (κ=.89 [cued condition] and 1.0 [relaxed condition] for occiput to wall status; intraclass correlation coefficients, .779-.897 for tragus to wall distance, C7 to wall distance, flexion angle, and inclinometric kyphosis measure). Convergent validity was supported for all measures by significant correlations between the same measures obtained during relaxed and cued conditions (eg, occiput to wall relaxed and cued) and for most measures by significant correlations between measures obtained under the same condition (eg, occiput to wall cued and tragus to wall cued). Significant correlations between tragus to wall distance, C7 to wall distance, flexion angle, and inclinometric kyphosis measure and the Unified Parkinson Disease Rating Scale item 28 (posture) also supported convergent validity. Significant differences between tragus to wall distance, C7 to wall distance, and inclinometric kyphosis measure values under relaxed and cued conditions supported known condition validity. Known group validity was demonstrated by significant differences in tragus to wall distance, C7 to wall distance, and inclinometric kyphosis measure obtained from individuals able and individuals unable to touch their occiput to wall when cued to stand tall.

Conclusions: Tragus to wall distance, C7 to wall distance, and inclinometric kyphosis measure are reliable and valid nonradiologic measures of forward flexed posture in PD.

Keywords: Parkinson disease; Physical examination; Posture; Psychometrics; Rehabilitation; Reproducibility of results.