A brief instrument to measure health-related quality-of-life in patients with bone metastasis: validation of the German version of Bone Metastases Quality-of-Life-10 (BOMET-QoL-10)

Figures & data

Figure 1. Sequence of the four questionnaires in the form administered to the patients. *DBQ was only used at baseline (T0).

Table 1. German version of the BOMET-QoL-10 questionnaire.

BOMET-QoL-10 questionnaire items in German^a	[1] Immer^b	[2] Fast immer^c	[3] Manchmal^d	[4] Selten^e	[5] Nie^f	Factor loading	Cronbach alpha*
1. Ich fühle mich müde.	□	□	□	□	□	0.69	0.91
2. Das Aufstehen aus dem Bett fällt mir sehr schwer.	□	□	□	□	□	0.75	0.90
3. Ich fühle mich allgemein unwohl.	□	□	□	□	□	0.76	0.90
4. Ich fühle mich niedergeschlagen und möchte am liebsten weinen.	□	□	□	□	□	0.58	0.91
5. Ich habe wenig Lust, aus dem Haus zu gehen.	□	□	□	□	□	0.67	0.91
6. Ich vermeide es, gemeinsam mit meiner Familie etwas zu unternehmen.	□	□	□	□	□	0.68	0.91
7. Aufgrund meiner Krankheit habe ich Schmerzen in einigen Körperbereichen wie im Rücken, in den Beinen, in der Hüfte …, die mein Leben beeinträchtigen.	□	□	□	□	□	0.80	0.90
8. Aufgrund meiner Krankheit habe ich Schmerzen, die mein Leben beeinträchtigen.	□	□	□	□	□	0.86	0.90
9. Aufgrund meiner Krankheit habe ich starke Schmerzen, die mich nicht in Ruhe lassen.	□	□	□	□	□	0.85	0.90
10. Aufgrund meiner krankheitsbedingten Schmerzen kann ich das Leben nicht so genieszen wie früher.	□	□	□	□	□	0.82	0.90

^aThe 10 items and the original Likert-type response scale (ranging from point 0 to point 4) in (non-validated) English language are to be found in the original BOMET-QoL-10 publication¹⁷; ^bImmer = Always; ^cFast immer = Almost always; ^dManchmal = Sometimes; ^eSelten = Seldom; ^fNie = Never.

*Cronbach alpha standardized, item deleted, as described in the Results section.

Table 2. Interpretation of correlation coefficients.

Size of correlation	Interpretation
0.90–1.00 (−0.90 to −1.00)	Very high positive (negative) correlation
0.70–0.90 (−0.70 to −0.90)	High positive (negative) correlation
0.50–0.70 (−0.50 to −0.70)	Moderate positive (negative) correlation
0.30–0.50 (−0.30 to −0.50)	Low positive (negative) correlation
0.00–0.30 (0.00 to −0.30)	Negligible correlation

Table 3. Effect size index (r) and respective value for small, medium, and large effects.

Effect size	r
Small	0.10
Medium	0.30
Large	0.50

Table 4. Characteristics of patients at inclusion.

Characteristic	n (%)
Number of patients	364
Age
Mean, years	66.4
StD, years	10.4
Median, years	68
Min – Max, years	36–88
Sex, n (%)
Female sex	261 (71.7%)
Male sex	103 (28.3%)
BMI
Mean, kg/m^2	26.6
95% CI lower–upper, kg/m^2	26.1–27.1
StD, kg/m^2	4.8
Median, kg/m^2	26
Min–Max, kg/m^2	16–44
Tumor entity, n (%)
Breast	236 (64.8%)
Lung	46 (12.6%)
Renal	15 (4.1%)
Prostate	67 (18.4%)
Disease status, n (%)
In remission	45 (12.4%)
Stable	238 (65.4%)
Progressive	81 (22.3%)
Status of metastatic disease, n (%)
Bone only	161 (44.2%)
Additional distant sites	203 (55.8%)
Time from diagnosis of metastatic disease to study inclusion
Mean, years	2.9
95% CI lower–upper, years	2.6–3.3
StD, years	3.4
Median, years	2
Min–Max, years	0–21
Time from diagnosis of BM to study inclusion
Mean, years	2.7
95% CI lower–upper, years	2.4–3.0
StD, years	3.3
Median, years	2
Min–Max, years	0–21
Comorbidities, n (%)
≥1 comorbidities	241 (66.2%)
Most frequent comorbidities (>5%), n (%)
Hypertension	142 (39.0%)
Chronic pulmonary disease	23 (6.3%)
Renal disease	21 (5.8%)
Diabetes with end organ damage	21 (5.8%)
Heart failure	19 (5.2%)
Charlson score, n (%)
0	269 (73.9%)
1	50 (13.7%)
2	33 (9.1%)
≥3	12 (3.3%)
ECOG performance status, n (%)
0	114 (31.3%)
1	141 (38.7%)
2	27 (7.4%)
3	1 (0.3%)
4	0 (0.0%)
Missing data records	81 (22.3%)

Abbreviations. StD, Standard deviation; BMI, Body mass index; CI, Confidence interval of the mean.

Figure 2. The BOMET-QoL-10 mean score and the scores of EORTC QLQ-BM22 (four different scales) depicted at inclusion, T1, T2, and T3.

Figure 3. Sensitivity of BOMET-QoL-10 to change in EORTC QLQ-BM22 scores. Corresponding changes in BOMET-QoL-10 mean scores are shown for patient groups who showed increased, stable (unchanged scores), or decreased EORTC QLQ-BM22 scores between the last available assessment and T0. An increased EORTC QLQ-BM22 score was defined as a ≥ 20 points higher score than T0, and a decreased score was defined as a ≥10 points lower score as compared to T0.

Table 5. Difference in BOMET-QoL-10 score compared to earlier time points.

Overall status of metastatic disease compared to earlier time points	Total n	Mean	StD	Min	Median	Max	95% CI (lower)	95% CI (upper)
Time point 1, n	304
In remission or SD (unchanged)	231	−2.5	13.5	−40	−2	50	−4.2	−0.7
Now PD (earlier in remission or SD)	8	−13.4	16.0	−35	−14	5	−26.8	0.0
PD (unchanged)	65	−1.0	12.9	−35	−3	38	−4.2	2.2
Unknown status	0	—	—	—	—	—	—	—
Time point 2, n	281
In remission or SD (unchanged)	199	−2.8	15.3	−70	−1	43	−5.0	−0.7
Now PD (earlier in remission or SD)	13	−7.1	16.1	−43	0	18	−16.8	2.7
PD (unchanged)	57	−2.7	13.5	−35	−3	33	−6.3	0.8
Unknown status	12	−5.8	15.1	−38	−4	18	−15.4	3.8
Time point 3, n	248
In remission or SD (unchanged)	142	−1.5	14.7	−38	−3	55	−4.0	0.9
Now PD (earlier in remission or SD)	27	−7.3	15.8	−50	−6	23	−13.5	−1.0
PD (unchanged)	59	−1.7	15.5	−35	−3	35	−5.7	2.4
Unknown status	20	−7.5	16.0	−45	−8	40	−15.0	0.0

A patient could fall into the group “Now PD (earlier in remission or SD)” only once, whereas a patient could fall into either of the other two groups multiple times.

Abbreviations. SD, stable disease; PD, progressive disease.

Table 6. Linear regression analysis: association of patient characteristics with BOMET-QoL-10 at inclusion.

Variable	Total n	Effect estimate^a	95% CI (lower)^a	95% CI (upper)^a	p-value
Univariate regression analysis
Age	348	0.018	−0.19	0.22	.87
Sex	348	−3.72	−8.55	1.10	.13
BMI	344	−0.14	−0.60	0.31	.54
Time from diagnosis of BM to enrolment	347	−0.0013	−0.0031	0.00045	.14
Time from diagnosis of metastatic disease to enrolment	348	−0.00019	−0.0019	0.0015	.83
Charlson score (score 0–score >0)	348	2.13	−2.78	7.05	.39
ECOG performance status	272	−9.13	−12.75	−5.51	<.0001*
Tumor entity overall	348				.26
Breast – Lung	345	−1.04	−7.72	5.65	.76
Breast – Prostate	345	−4.41	−10.11	1.30	.13
Breast – Renal	345	6.49	−4.67	17.66	.25
Lung – Prostate	345	−3.37	−11.29	4.55	.40
Lung – Renal	345	7.53	−4.91	19.97	.23
Prostate – Renal	345	10.90	−1.05	22.85	.07
Current disease status overall	348				.07
In remission – PD	346	4.56	−3.06	12.18	.24
In remission – SD	346	−1.62	−8.28	5.04	.63
PD – SD	346	−6.19	−11.49	−0.88	.02*
Current status of metastatic disease (BM only – other locations)	348	−0.43	−4.82	3.96	.85
Multiple regression analysis
Age	269	0.14	−0.10	0.38	.26
Sex	269	−0.48	−12.41	11.45	.94
BMI	269	−0.22	−0.71	0.27	.38
Time from diagnosis of BM to enrolment	269	−0.0073	−0.012	−0.0030	.0009*
Time from diagnosis of metastatic disease to enrolment	269	0.0063	0.0023	0.010	.0022*
Charlson score	269	−1.54	−7.09	4.008	.58
ECOG performance status	269	−10.05	−13.84	−6.26	<.0001*
Tumor entity overall	269				.80
Breast – Lung	269	−1.74	−11.42	7.95	.72
Breast – Prostate	269	−2.05	−15.47	11.36	.76
Breast – Renal	269	4.49	−10.61	19.58	.56
Lung – Prostate	269	−0.32	−11.58	10.94	.96
Lung – Renal	269	6.22	−8.10	20.55	.39
Prostate – Renal	269	6.54	−7.13	20.21	.35
Current disease status overall	269				.85
In remission – PD	269	1.69	−6.85	10.22	.70
In remission – SD	269	−0.28	−7.14	6.58	.94
PD – SD	269	−1.97	−8.68	4.75	.56
Current status of metastatic disease (BM only – other locations)	269	−2.18	−7.07	2.70	.38

*Significant results (p < .05).

^aEffect estimates refer to change in BOMET-QoL-10 for one unit increase in variable. Solution for fixed effects (age, BMI, time from diagnosis of BM to enrolment, time from diagnosis of metastatic disease to enrolment, ECOG) or differences of least squares means (sex, Charlson score, tumor entity, current disease status, current status of metastatic disease) was used to determine the effect estimate.

Abbreviations. BMI, Body mass index; BM, bone metastases; SD, stable disease; PD, progressive disease; CI, Confidence interval of the mean.

Sureda A, Isla D, Cózar JM, et al. Final development and validation of the BOMET-QoL questionnaire for assessing quality of life in patients with malignant bone disease due to neoplasia. J Med Econ 2007;10:27-39

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