Table 5. Principal component (PC) analysis outcomes and inter-observer agreement (using Kendall’s W) for QBA rating scales.

	PC1	PC2	PC3	PC4
Eigenvalue	5.66	5.18	1.78	1.56
% explained variance	28.3	25.9	8.9	7.8
% cumulative variance	28.3	54.2	63.1	70.9
Kendall W	0.61	0.80	0.71	0.60
p-value	p<0.001	p<0.001	p<0.001	p<0.001