Assessing postural balance in early Parkinson's Disease-validity of the BDL balance scale.

BACKGROUND: There is a need for a valid assessment test of balance in early Parkinson's disease (PD).

OBJECTIVE: To validate the Bäckstrand Dahlberg Liljenäs Balance Scale (BDL), a test of balance performance constructed to assess mild to moderate balance disability due to neurological disease, for use in persons with early PD.

METHODS: Cross-sectional psychometric evaluation study from a convenience sample community-dwelling persons with PD (n = 28).

MAIN MEASURES: The BDL was validated using the Berg Balance Scale (BBS), the motor part of the Unified Parkinson's Disease Rating Scale (mUPDRS), the Timed Up and Go (TUG) and Timed Up and Go-cognition (CTUG). Correlations were calculated by Spearman's rank correlation coefficient (rho). Rasch analyses were used to test the internal construct of the BDL. The result from the BDL was compared to a healthy reference group.

RESULTS: The correlation between the BDL and the BBS (rho = 0.703) was high positive, while for mUPDRS (rho = -0.280), TUG (rho = -0.321) and CTUG (rho = -0.361) the correlations with the BDL were negligible to low negative. The Rasch analyses for the BDL showed a good distribution of the task difficulties with neither ceiling nor floor effect among individual measures. There was a significant difference (p = 0.03) in performance of the BDL between the PD group and the healthy reference group.

CONCLUSIONS: The BDL Balance Scale can be considered a valid clinical assessment test when evaluating balance training interventions in persons with early PD. It can be recommended as an outcome measure in clinical practice and in clinical research within this population.