J Neurol Res

Journal of Neurology Research, ISSN 1923-2845 print, 1923-2853 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Neurol Res and Elmer Press Inc

Journal website http://www.neurores.org

Original Article

Volume 1, Number 4, October 2011, pages 153-160

Serbian Validation of the Individualized Neuromuscular Quality of Life Questionnaire (INQoL) in Adults With Myotonic Dystrophy Type 1

Figure 1. Criterion-related validity of INQoL in DM1 patients: correlation of INQoL scores with severity of disease (MIRS) (n = 102, **P < 0.01).

**Table 1.** Demographic and Clinical Characteristics of Investigated DM1 Patients
Patients characteristics	All patients (n = 102)	Test-retest subgroup (n = 30)
^*P < 0.05.
Gender (%)
Male	46.1	50.0
Female	53.9	50.0
Age (mean years ± SD)	45.8 ± 12.1	48.4 ± 8.6
Educational level* (mean years ± SD)	11.1 ± 2.6	12.8 ± 1.9
Duration of disease (mean years ± SD)	19.6 ± 9.5	22.6 ± 16.0
Severity of disease (MIRS) (%)
II	19.6	13.3
III	28.4	26.7
IV	31.4	43.3
V	20.6	16.7

Table 1. Demographic and Clinical Characteristics of Investigated DM1 Patients

Patients characteristics

All patients (n = 102)

Test-retest subgroup (n = 30)

^*P < 0.05.

Gender (%)

Male

46.1

50.0

Female

53.9

50.0

Age (mean years ± SD)

45.8 ± 12.1

48.4 ± 8.6

Educational level* (mean years ± SD)

11.1 ± 2.6

12.8 ± 1.9

Duration of disease (mean years ± SD)

19.6 ± 9.5

22.6 ± 16.0

Severity of disease (MIRS) (%)

19.6

13.3

III

28.4

26.7

31.4

43.3

20.6

16.7

**Table 2.** Reliability and Content-related Validity of INQoL in DM1 Patients
INQoL domain	Internal consistency (n = 102)	Reproducibility (n = 30)	Content-related validity (n = 102)
Weakness	0.907	0.910	0.760-0.848	0.545-0.768
Locking	0.910	0.895	0.753-0.829	0.344-0.760
Pain	0.946	0.931	0.875-0.917	0.455-0.680
Fatigue	0.961	0.979	0.910-0.915	0.621-0.738
Activities	0.903	0.934	0.618-0.833	0.356-0.807
Independence	0.911	0.867	0.755-0.862	0.535-0.802
Social relationships	0.934	0.713	0.579-0.805	0.395-0.704
Emotions	0.898	0.843	0.729-0.820	0.340-0.734
Body image	0.864	0.801	0.695-0.751	0.538-0.705
Perceived treatment	0.625	0.888	0.008-0.196	/
Expected treatment	0.625	0.854	0.054-0.742	/

Table 2. Reliability and Content-related Validity of INQoL in DM1 Patients

INQoL domain

Internal consistency (n = 102)

Reproducibility (n = 30)

Content-related validity (n = 102)

Cronbach’s alpha

Intraclass correlation coefficient

Item internal consistency (Spearman’s rho)

Item discriminant validity (Spearman’s rho)

Weakness

0.907

0.910

0.760-0.848

0.545-0.768

Locking

0.910

0.895

0.753-0.829

0.344-0.760

Pain

0.946

0.931

0.875-0.917

0.455-0.680

Fatigue

0.961

0.979

0.910-0.915

0.621-0.738

Activities

0.903

0.934

0.618-0.833

0.356-0.807

Independence

0.911

0.867

0.755-0.862

0.535-0.802

Social relationships

0.934

0.713

0.579-0.805

0.395-0.704

Emotions

0.898

0.843

0.729-0.820

0.340-0.734

Body image

0.864

0.801

0.695-0.751

0.538-0.705

Perceived treatment

0.625

0.888

0.008-0.196

Expected treatment

0.625

0.854

0.054-0.742

**Table 3.** Scores on INQoL in DM1 Patients (n = 102)
INQoL domain	Score	Range	Ceiling effect (%)	Floor effect (%)
Weakness	65.89 ± 28.77	0.00 - 100.00	14.71	2.94
Locking	59.80 ± 30.62	0.00 - 100.00	8.82	1.96
Pain	39.32 ± 34.35	0.00 - 100.00	2.94	28.43
Fatigue	54.28 ± 36.43	0.00 - 100.00	11.76	18.63
Activities	54.56 ± 32.20	0.00 - 100.00	0.98	2.94
Independence	46.40 ± 34.71	0.00 - 100.00	3.92	12.75
Social relationships	22.41 ± 24.13	0.00 - 96.29	0.00	17.65
Emotions	38.43 ± 28.19	0.00 - 97.22	0.00	7.84
Body image	49.10 ± 30.81	0.00- 100.00	2.94	11.76
Perceived treatment	25.33 ± 29.83	-33.33 - 100.00	1.96	0.00
Expected treatment	32.52 ± 36.92	-50.00 - 100.00	1.96	0.00
QoL total	46.82 ± 26.07	0.00 - 92.78	0.00	0.98

Table 3. Scores on INQoL in DM1 Patients (n = 102)

INQoL domain

Score

Range

Ceiling effect (%)

Floor effect (%)

Weakness

65.89 ± 28.77

0.00 - 100.00

14.71

2.94

Locking

59.80 ± 30.62

0.00 - 100.00

8.82

1.96

Pain

39.32 ± 34.35

0.00 - 100.00

2.94

28.43

Fatigue

54.28 ± 36.43

0.00 - 100.00

11.76

18.63

Activities

54.56 ± 32.20

0.00 - 100.00

0.98

2.94

Independence

46.40 ± 34.71

0.00 - 100.00

3.92

12.75

Social relationships

22.41 ± 24.13

0.00 - 96.29

0.00

17.65

Emotions

38.43 ± 28.19

0.00 - 97.22

0.00

7.84

Body image

49.10 ± 30.81

0.00- 100.00

2.94

11.76

Perceived treatment

25.33 ± 29.83

-33.33 - 100.00

1.96

0.00

Expected treatment

32.52 ± 36.92

-50.00 - 100.00

1.96

0.00

QoL total

46.82 ± 26.07

0.00 - 92.78

0.00

0.98

**Table 4.** Construct-related Validity of INQoL in DM1 Patients (n = 102)
INQoL domain	Gender (U test)	Age (Spearman’s rho)	Educational level (Spearman’s rho)	Duration of disease (Spearman’s rho)
P < 0.05, *P < 0.01.
Weakness	67.9 ± 27.6	64.2 ± 29.9	0.470**	-0.111	0.446^**
Locking	60.6 ± 31.5	59.1 ± 30.1	0.283**	-0.165	0.380^**
Pain	44.5 ± 34.6	34.9 ± 33.8	0.446**	0.174	0.381^**
Fatigue	59.3 ± 35.8	50.0 ± 36.7	0.434**	-0.183	0.351^**
Activities	57.2 ± 30.8	52.3 ± 33.5	0.508**	-0.235*	0.444^**
Independence	47.9 ± 32.4	45.2 ± 36.8	0.409**	-0.193	0.485^**
Social relationships	21.2 ± 21.5	23.5 ± 26.4	0.300**	-0.115	0.299^**
Emotions	42.4 ± 26.3	35.0 ± 29.5	0.353**	-0.178	0.302^**
Body image	50.6 ± 31.1	47.8 ± 30.8	0.387**	-0.166	0.347^**
Perceived treatment	25.5 ± 31.2	25.2 ± 28.8	-0.031	-0.131	-0.046
Expected treatment	34.6 ± 36.3	30.8 ± 37.7	-0.016	-0.155	-0.200
QoL total score	49.5 ± 24.5	44.5 ± 27.4	0.419**	-0.218*	0.379^**

Table 4. Construct-related Validity of INQoL in DM1 Patients (n = 102)

INQoL domain

Gender (U test)

Age (Spearman’s rho)

Educational level (Spearman’s rho)

Duration of disease (Spearman’s rho)

Male

Female

*P < 0.05, **P < 0.01.

Weakness

67.9 ± 27.6

64.2 ± 29.9

0.470**

-0.111

0.446^**

Locking

60.6 ± 31.5

59.1 ± 30.1

0.283**

-0.165

0.380^**

Pain

44.5 ± 34.6

34.9 ± 33.8

0.446**

0.174

0.381^**

Fatigue

59.3 ± 35.8

50.0 ± 36.7

0.434**

-0.183

0.351^**

Activities

57.2 ± 30.8

52.3 ± 33.5

0.508**

-0.235*

0.444^**

Independence

47.9 ± 32.4

45.2 ± 36.8

0.409**

-0.193

0.485^**

Social relationships

21.2 ± 21.5

23.5 ± 26.4

0.300**

-0.115

0.299^**

Emotions

42.4 ± 26.3

35.0 ± 29.5

0.353**

-0.178

0.302^**

Body image

50.6 ± 31.1

47.8 ± 30.8

0.387**

-0.166

0.347^**

Perceived treatment

25.5 ± 31.2

25.2 ± 28.8

-0.031

-0.131

-0.046

Expected treatment

34.6 ± 36.3

30.8 ± 37.7

-0.016

-0.155

-0.200

QoL total score

49.5 ± 24.5

44.5 ± 27.4

0.419**

-0.218*

0.379^**

**Table 5.** Concurrent Validity of INQoL in DM1 Patients (n = 102)
INQoL domain (A)	Comparable SF-36 domain (B)	Correlation between (A) and (B)	Beta for correlation between (A) and MIRS	Beta for correlation between (B) and MIRS
P < 0.05, *P < 0.01.
Weakness	Physical functioning	-0.733**	0.263	-0.610^**
Locking	/	/	-0.249	/
Pain	Bodily pain	-0.668**	-0.265*	0.150
Fatigue	Vitality	-0.678**	0.055	-0.120
Activities	Physical functioning	-0.800**	0.124	-0.610^**
Independence	/	/	0.568**	/
Social relationships	Social functioning	-0.522**	-0.140	-0.165
Emotions	Mental health	-0.608**	0.103	0.077
Body image	/	/	0.119	/
Total QoL score	Physical composite score	-0.774**	/	/
Total QoL score	Mental composite score	-0.719**	/	/
			adjusted R² = 0.430	adjusted R² = 0.421

Table 5. Concurrent Validity of INQoL in DM1 Patients (n = 102)

INQoL domain (A)

Comparable SF-36 domain (B)

Correlation between (A) and (B)

Beta for correlation between (A) and MIRS

Beta for correlation between (B) and MIRS

*P < 0.05, **P < 0.01.

Weakness

Physical functioning

-0.733**

0.263

-0.610^**

Locking

-0.249

Pain

Bodily pain

-0.668**

-0.265*

0.150

Fatigue

Vitality

-0.678**

0.055

-0.120

Activities

Physical functioning

-0.800**

0.124

-0.610^**

Independence

0.568**

Social relationships

Social functioning

-0.522**

-0.140

-0.165

Emotions

Mental health

-0.608**

0.103

0.077

Body image

0.119

Total QoL score

Physical composite score

-0.774**

Total QoL score

Mental composite score

-0.719**

adjusted R² = 0.430

adjusted R² = 0.421