Background and aims: The aim of the present study was to measure the test-retest validity of Parkinson's Disease Sleep Scale 2nd version (PDSS-2) on PD patients with stable medication and motor symptoms over the period of 4 weeks.
Methods: The subject population consisted of 92 PD patients. Besides PDSS-2, Unified PD rating scale, Montgomery-Asberg Depression Rating Scale and EQ-5D were assessed at baseline and 4 weeks later.
Results: The total score of PDSS-2 decreased from 19.06 ± 10.78 points to 18.00 ± 9.34 points (p > 0.05). For the total score of PDSS-2 the Intra-class and Lin's Concordance Correlation Coefficients were 0.782 and 0.799. The average difference between the baseline and follow-up total PDSS-2 scores was -1.06 points with the 95% confidence interval of -7.96 and +5.84 points.
Conclusions: Our data supports that the items and the total score of PDSS-2 have acceptable test-retest reliability over a four week period on patients with stable PD symptoms and pharmacological therapy.
Keywords: Sleep; concordance; intraclass correlation coefficient; scale.