Evaluation of reliability and validity of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30, Albanian version) among breast cancer patients from Kosovo

Figures & data

Table 1 Sociodemographic and clinical characteristics of the study sample (n=62)

Characteristics	Number of patients	%
Age (years)
20–39	11	17.7
40–59	38	61.3
60–80	13	21
Education level
No school	8	12.9
Primary	31	50
Secondary	13	21
High school/university	10	16.1
Marital status
Single	5	8.1
Married	57	91.9
Chemotherapy
No	2	3.2
Yes	60	96.8
Surgery
No	6	9.7
Mastectomy	51	82.3
Lumpectomy	1	1.6
Quadrantectomy	4	6.5
Radiotherapy
Yes	49	79
No	13	21
Disease stage
0–I	7	11.3
II	19	30.6
III–IV	36	58.1
Distant metastasis
No	44	71
Yes	18	29

Table 2 Mean scores and internal consistency of each subscale/item of EORTC QLQ-C30 (n=62)

	Mean score (SD)	Cronbach’s alpha coefficientsa
Functional scaleb
Physical (1–5)c	82.58 (16.34)	0.81
Role (6, 7)c	65.6 (20.88)	0.81
Emotional (21–24)c	57.13 (21.6)	0.86
Cognitive (20, 25)c	65.05 (27.61)	0.54
Social (26, 27)c	54.53 (19.67)	0.8
Global health quality of life (29, 30)c	78.9 (17.63)	0.96
Symptom scale and/or itemsd
Fatigue (10, 12, 18)c	19.61 (24.6)	0.91
Nausea and vomiting (14, 15)c	6.99 (19.21)	0.77
Pain (9, 19)c	20.16 (23.2)	0.83
Dyspnea (8)c	19.35 (28.01)
Insomnia (11)c	40.33 (40.1)
Appetite loss (13)c	21.5 (34.2)
Constipation (16)c	1.61 (12.7)
Diarrhea (17)c	6.45 (19.87)
Financial difficulties (28)c	92.47 (22.92)

Notes:

a Alpha ≥0.70 indicates acceptable scale reliability;

b scores range from 0 to 100 – higher score indicates better functioning or GH/QoL;

c numbers in brackets correspond to the item numbers in the questionnaire;

d scores range from 0 to 100 – higher score indicates a higher rate of symptoms or problems.

Abbreviations: EORTC QLQ-C30, European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire; GH/QoL, global health quality of life; SD, standard deviation.

Table 3 Spearman’s correlation coefficients between the items and the subscales of the EORTC QLQ-C30

Item correlations		Subscales
Item noa	Short descriptionb	PF	RF	EF	CF	SF	GH/QoL	FA	NV	PA
1	Strenuous activities	−0.79c	−0.37	−0.3	−0.34	−0.17	−0.65	0.63	0.21	0.54
2	Long walk	−0.77	−0.34	−0.32	−0.26	−0.41	−0.45	0.5	0.34	0.44
3	Short walk	−0.60	−0.11	−0.34	−0.23	−0.28	−0.58	0.51	0.29	0.44
4	Stay in bed/chair	−0.70	−0.08	−0.20	−0.30	−0.27	−0.55	0.68	0.44	0.56
5	Self-care	−0.22	−0.23	−0.21	−0.20	−0.23	−0.23	0.22	0.33	0.23
6	Limited in work	−0.30	−0.82	−0.21	−0.13	−0.42	−0.23	0.25	0.06	0.17
7	Hobbies/limited leisure activities	−0.33	−0.96	−0.30	−0.19	−0.31	−0.25	0.24	0.05	0.20
21	Tense	−0.22	−0.18	−0.75	−0.20	−0.15	−0.12	0.18	0.19	0.17
22	Worried	−0.26	−0.19	−0.85	−0.39	−0.43	−0.26	0.11	0.29	0.28
23	Irritated	−0.30	−0.16	−0.84	−0.16	−0.18	−0.22	0.15	0.26	0.22
24	Depressed	−0.40	−0.31	−0.74	−0.37	−0.36	−0.38	0.35	0.24	0.31
20	Concentration	−0.18	−0.06	−0.25	−0.76	−0.34	−0.41	0.29	0.20	0.39
25	Memory difficulties	−0.35	−0.11	−0.32	−0.89	−0.40	−0.41	0.32	0.20	0.18
26	Family life	−0.33	−0.41	−0.35	−0.39	−0.85	−0.25	0.23	0.26	0.19
27	Social life	−0.41	−0.36	−0.39	−0.44	−0.84	−0.42	0.42	0.52	0.29
29	Physical condition	0.71	0.18	0.34	0.48	0.36	0.98	−0.73	−0.45	−0.69
30	General QoL	0.62	0.21	0.34	0.51	0.40	0.98	−0.69	−0.40	−0.60
10	Need to rest	−0.57	−0.26	−0.22	−0.27	−0.37	−0.60	0.89	0.48	0.60
12	Felt weak	−0.61	−0.20	−0.26	−0.35	−0.41	−0.68	0.83	0.54	0.60
18	Felt tired	−0.71	−0.07	−0.26	−0.30	−0.21	−0.63	0.78	0.47	0.62
14	Nausea	−0.41	−0.02	−0.26	−0.25	−0.44	−0.43	0.49	0.95	0.45
15	Vomiting	−0.31	0.02	−0.30	−0.14	−0.17	−0.33	0.28	0.71	0.30
9	Had pain	−0.52	−0.13	−0.26	−0.36	−0.27	−0.59	0.59	0.46	0.90
19	Pain interfered	−0.65	−0.20	−0.32	−0.25	−0.28	−0.60	0.68	0.38	0.89

Notes:

a The item number corresponds to the number of each item in the questionnaire;

b Short description, explains briefly the questions asked in each item of the questionnaire;

c Spearman’s correlation coefficients between the subscales and items within the same subscale (in bold).

Abbreviations: CF, cognitive functioning; EF, emotional functioning; EORTC QLQ-C30, European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire; FA, fatigue; GH/QoL, global health quality of life; NV, nausea and vomiting; RF, role functioning; PA, pain; PF, physical functioning; QoL, quality of life; SF, social functioning.

Table 4 Spearman’s correlation coefficients of subscales in the Albanian version of the EORTC QLQ-C30

Scales	PF	RF	EF	CF	SF	GH/QoL	FA	NV
PF
RF	0.34**
EF	0.38**	0.28*
CF	0.34**	0.13	0.36**
SF	0.42**	0.37**	0.38**	0.44**
GH/QoL	0.68**	0.19**	0.35**	0.50**	0.38**
FA	−0.72**	−0.22	−0.23	−0.37**	−0.38**	−0.73**
NV	−0.40**	−0.02	−0.25*	−0.25	−0.45**	−0.43**	0.50**
PA	−0.64**	−0.17	−0.32*	−0.34**	−0.29*	−0.66**	0.70**	0.46**

Notes:

* Correlation is significant at the 0.05 level (two-tailed);

** correlation is significant at the 0.01 level (two-tailed); negative correlations are due to scoring procedures.

Abbreviations: CF, cognitive functioning; EF, emotional functioning; EORTC QLQ-C30, European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire; FA, fatigue; GH/QoL, global health quality of life; NV, nausea and vomiting; RF, role functioning; PA, pain; PF, physical functioning; SF, social functioning.

Table 5 Summary of the EORTCQLQ-C30 subscales by disease stage

Disease stage	0–I	II	III–IV	P-value*
	n=7	n=19	n=36
Symptom scale	Mean (SD)	Mean (SD)	Mean (SD)
Fatigue	10.9 (13.0)	19.6 (23.7)	21.3 (26.8)	0.68
Nausea and vomiting	0.0 (0.0)	5.3 (13.7)	9.3 (23.0)	0.44
Pain	11.9 (15.9)	21.0 (24.1)	21.3 (24.1)	0.63
Dyspnea	14.3 (17.8)	12.8 (27.7)	24.1 (29.4)	0.16
Insomnia	42.9 (46.0)	42.1 (41.3)	38.9 (39.4)	0.94
Appetite loss	4.8 (12.6)	19.3 (33.9)	25.9 (36.6)	0.26
Constipation	0.0 (0.0)	0.0 (0.0)	2.8 (16.7)	0.70
Diarrhea	4.8 (12.6)	7.0 (23.8)	6.5 (19.2)	0.95
Financial difficulties	85.7 (26.2)	96.5 (15.3)	92.5 (22.9)	0.29

Note:

* P<0.05 is considered statistically significant.

Abbreviations: EORTC QLQ-C30, European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire; SD, standard deviation.

Table 6 Summary of the EORTC QLQ-C30 subscales by education level

Education level	No school	Primary	Secondary	High school/university	P-value*
	n=8	n=31	n=13	n=10
Functional scale	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
Physical functioning	78.3 (6.9)	82.6 (14.1)	86.7 (12.5)	80.7 (29.4)	0.17
Role functioning	66.7 (25.2)	65.6 (15.5)	71.8 (21.9)	56.7 (29.6)	0.42
Cognitive functioning	47.9 (18.8)	61.3 (28.7)	71.8 (21.9)	81.7 (28.8)	0.03
Emotional functioning	60.4 (23.9)	55.4 (15.6)	56.4 (29.5)	60.8 (26.7)	0.27
Social functioning	56.3 (15.3)	62.9 (14.8)	68.0 (25.9)	71.7 (26.1)	0.31
GH/QoL	65.6 (10.4)	77.7 (15.9)	86.6 (13.4)	83.3 (26.0)	0.009

Note:

* P<0.05 is considered statistically significant.

Abbreviations: EORTC QLQ-C30, European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire; GH/QoL, global health quality of life; SD, standard deviation.