Table 3.

Four-domain structure and corresponding factor loadings obtained by principal component analysis of 134 European patients with chronic rhinosinusitis

Item number	Item wording	Domain
		Nasal symptoms	Otologic symptoms	Sleep symptoms	Emotional symptoms
1	Need to blow your nose	0.86	0.36	0.35	0.27
2	Sneezing	0.63	0.44	0.18	0.18
3	Running nose	0.84	0.25	0.06	0.25
4	Cough*	0.43	0.23	0.25	0.17
5	Post-nasal discharger	0.60	0.33	0.33	0.41
6	Thick nasal discharger	0.77	0.36	0.43	0.27
7	A feeling of full or stuffed ear	0.49	0.82	0.45	0.26
8	Dizziness or vertigo	0.14	0.77	0.32	0.49
9	Earache	0.25	0.82	0.30	0.27
10	Facial pain or pressure#,*	0.49	0.47	0.41	0.35
11	Difficulty sleeping	0.23	0.40	0.89	0.46
12	Wake up in the middle of the night	0.27	0.42	0.90	0.38
13	Lack of a good night’s sleep	0.35	0.39	0.92	0.47
14	Wake up tired	0.36	0.32	0.73	0.71
15	Fatigued or tired during the day	0.43	0.41	0.69	0.76
16	Reduced productivity	0.46	0.39	0.57	0.79
17	Reduced concentration	0.34	0.44	0.37	0.79
18	Frustrated, restless or irritated	0.40	0.41	0.52	0.81
19	Sadness	0.14	0.34	0.47	0.79
20	A feeling of shame	0.22	0.36	0.19	0.50
21	Difficulty to feel ‘smells’ or ‘tastes’	0.51	0.23	0.33	− 0.09
22	Stuffed nose	0.76	0.24	0.43	0.31

Bold items show the highest factor loadings obtained by principal component analysis per domain for each item

*Item with low factor loading < 0.5

^#Ambiguous item with significant cross-loading