Internal consistency and item-total correlation of patient-reported outcome instruments and hemophilia joint health score v2.1 in US adult people with hemophilia: results from the Pain, Functional Impairment, and Quality of life (P-FiQ) study

Figures & data

Table 1 Internal consistency of patient-reported outcome and HJHS scores

Item	n	Cronbach’s alpha
EQ-5D-5L
Index	375	0.81
BPI
Pain severity	372	0.92
Pain interference	375	0.96
IPAQ
Total physical activitya	208	0.51*
SF-36v2
Physical functioning	376	0.94
Role physical	374	0.96
Bodily pain	379	0.87
General health	376	0.82
Vitality	379	0.79
Social functioning	377	0.86
Role emotional	377	0.96
Mental health	375	0.86
Physical health summary	361	0.96
Mental health summary	361	0.96
HAL
Lying/sitting/kneeling/standing	368	0.94
Functions of the legs	372	0.96
Functions of the arms	378	0.89
Use of transportation	377	0.58*
Self-care	379	0.90
Household tasks	378	0.92
Leisure activities and sports	377	0.89
Upper extremity activities	376	0.92
Basic lower extremity activities	375	0.96
Complex lower extremity activities	370	0.94
Total score	348	0.98
HJHS
Total score	228	0.97

Notes:

a Excluding participants with no reported physical activity.

* Cronbach’s alpha ≤0.70.

Abbreviations: BPI, Brief Pain Inventory v2 Short Form; HAL, Hemophilia Activities List; HJHS, Hemophilia Joint Health Score v2.1; IPAQ, International Physical Activity Questionnaire; SF-36v2, Short Form 36 Health Survey v2.

Table 2 Item-total correlation: EQ-5D-5L, BPI, and IPAQ

Item	Pearson’s r	Alphaa
EQ-5D-5L index
Mobility	0.70	0.74
Self-care	0.53	0.80
Usual activities	0.71	0.73
Pain/discomfort	0.73	0.73
Anxiety/depression	0.39	0.83
BPI pain severity
Worst pain	0.79	0.92
Least pain	0.79	0.91
Average pain	0.88	0.88
Current pain	0.85	0.89
BPI pain interference
General activity	0.90	0.95
Mood	0.88	0.95
Walking ability	0.79	0.96
Normal work	0.87	0.95
Relations with other people	0.82	0.95
Sleep	0.82	0.95
Enjoyment of life	0.88	0.95
IPAQ total physical activityb
Walking	0.50	0.26
Moderate intensity activities	0.67	0.13
Vigorous intensity activities	0.12*	0.64

Notes:

a Indicates internal consistency of remaining items if the elected item were deleted from the total score.

b Excluding participants with no reported physical activity.

* r≤0.20.

Abbreviations: BPI, Brief Pain Inventory v2 Short Form; IPAQ, International Physical Activity Questionnaire; r, Pearson’s product-moment correlation with the total score.

Table 3 Item-total correlation: SF-36v2

Item	Pearson’s r	Alphaa
Physical functioning
Vigorous activity	0.68	0.94
Moderate activity	0.80	0.93
Lifting or carrying groceries	0.75	0.94
Climbing several flights of stairs	0.83	0.93
Climbing one flight of stairs	0.80	0.93
Bending, kneeling, or stooping	0.73	0.94
Walking more than a mile	0.84	0.93
Walking several hundred yards	0.86	0.93
Walking one hundred yards	0.78	0.93
Bathing or dressing	0.50	0.94
Role physical
Cut down amount of work time due to physical health	0.89	0.95
Accomplished less than you would like, due to physical health	0.90	0.94
Limited in the kind of work, due to physical health	0.89	0.95
Difficulty performing work, due to physical health	0.90	0.94
Bodily pain
Bodily pain during past 4 weeks	0.77	NA
Pain interference, normal work	0.77	NA
General health
General health status	0.70	0.76
Get sick a little easier than others	0.69	0.76
Healthy as others	0.76	0.74
Expect health will get worse	0.42	0.84
Health is excellent	0.52	0.81
Vitality
Feel full of life	0.56	0.76
Have a lot of energy	0.62	0.73
Feel worn out	0.63	0.73
Feel tired	0.61	0.74
Social functioning
Severity of interference with normal social activity	0.76	NA
Time of interference with social activities	0.76	NA
Role emotional
Cut down amount of work time, due to emotional health	0.93	0.92
Accomplished less than you would like, due to emotional health	0.92	0.93
Worked less carefully than usual, due to emotional health	0.87	0.96
Mental health
Feel calm and peaceful	0.65	0.83
Feel happy	0.62	0.84
Feel very nervous	0.62	0.84
Feel down in the dumps	0.72	0.82
Feel downhearted and depressed	0.76	0.80

Note:

a Indicates internal consistency of remaining items if the elected item were deleted from the total score.

Abbreviations: NA, not assessable; r, Pearson’s product-moment correlation with the total score; SF-36v2, Short Form 36 Health Survey v2.

Table 4 Item-total correlation: Hemophilia Activities List

Item	Pearson’s r	Alphaa
Lying/sitting/kneeling/standing
Sitting down	0.68	0.94
Rising from a chair with armrests	0.80	0.93
Rising from a chair without armrests	0.83	0.93
Kneeling/squatting	0.88	0.93
Bending forward	0.72	0.94
Kneeling long time	0.86	0.93
Squatting long time	0.86	0.93
Standing long time	0.79	0.93
Functions of the legs
Walking long distances	0.81	0.96
Walking on a soft surface	0.89	0.96
Walking on an uneven surface	0.87	0.96
Strolling	0.89	0.96
Climbing up the stairs	0.84	0.96
Climbing down the stairs	0.89	0.96
Running	0.88	0.96
Jumping	0.82	0.96
Functions of the arms
Lifting heavy objects	0.84	0.82
Carrying heavy objects	0.87	0.81
Fine hand movements	0.65	0.90
Reaching above your head	0.72	0.87
Use of transportation
Riding a bicycle	0.49	0.39
Getting in and out of car	0.45	0.44
Using public transportation	0.34	0.57
Self-care
Drying your whole body	0.82	0.87
Putting on a shirt, sweater, etc.	0.83	0.87
Putting on socks and shoes	0.78	0.88
Putting on a tie	0.74	0.89
Going to the toilet	0.67	0.90
Household tasks
Going out shopping	0.72	0.91
Washing the dishes	0.83	0.90
Cleaning the house	0.89	0.89
Other household tasks	0.85	0.90
Doing odd jobs	0.86	0.89
Gardening	0.60	0.94
Leisure activities and sports
Playing games (outdoors)	0.69	0.87
Sports	0.72	0.88
Going out (theater/museum/bar)	0.76	0.87
Hobbies	0.64	0.88
Dancing	0.67	0.88
Going on a holiday (active)	0.76	0.87
Going on a holiday (passive/beach/hotel)	0.72	0.87
Upper extremity activities
Lifting heavy objects	0.73	0.91
Carrying heavy objects	0.75	0.91
Fine hand movements	0.74	0.91
Reaching above your head	0.78	0.90
Drying your whole body	0.75	0.91
Putting on a shirt, sweater, etc.	0.78	0.91
Putting on socks and shoes	0.73	0.91
Putting on a tie	0.72	0.91
Going to the toilet	0.62	0.92
Basic lower extremity activities
Standing long time	0.77	0.96
Walking short distances	0.86	0.95
Walking long distances	0.92	0.94
Walking on a soft surface	0.88	0.95
Walking on an uneven surface	0.89	0.94
Strolling	0.87	0.95
Complex lower extremity activities
Rising from a chair without armrests	0.75	0.94
Kneeling/squatting	0.88	0.93
Kneeling long time	0.85	0.93
Squatting long time	0.86	0.93
Climbing up the stairs	0.84	0.94
Climbing down the stairs	0.84	0.94
Running	0.84	0.93
Jumping	0.86	0.93
Riding a bicycle	0.44	0.96

Note:

a Indicates internal consistency of remaining items if the elected item were deleted from the total score.

Abbreviation: r, Pearson’s product-moment correlation with the total score.

Table 5 Item-total correlation: Hemophilia Joint Health Score

Item	Elbow (n=232)		Knee (n=231)		Ankle (n=232)		Total (n=228)
	Pearson’s r	Alphaa	Pearson’s r	Alphaa	Pearson’s r	Alphaa	Pearson’s r	Alphaa
Swelling, left	0.48	0.89	0.73	0.95	0.67	0.91	0.54	0.97
Swelling, right	0.42	0.90	0.76	0.94	0.62	0.91	0.59	0.97
Duration (swelling), left	0.57	0.89	0.75	0.94	0.55	0.91	0.56	0.97
Duration (swelling), right	0.51	0.89	0.71	0.95	0.59	0.91	0.59	0.97
Atrophy, left	0.70	0.89	0.81	0.94	0.67	0.91	0.68	0.97
Atrophy, right	0.62	0.89	0.83	0.94	0.64	0.91	0.70	0.97
Crepitus, left	0.69	0.89	0.77	0.94	0.74	0.90	0.66	0.97
Crepitus, right	0.61	0.89	0.76	0.94	0.73	0.90	0.68	0.97
Flexion loss, left	0.71	0.88	0.74	0.94	0.70	0.90	0.66	0.97
Flexion loss, right	0.67	0.89	0.77	0.94	0.68	0.90	0.70	0.96
Extension loss, left	0.71	0.88	0.74	0.94	0.69	0.90	0.67	0.97
Extension loss, right	0.67	0.89	0.75	0.94	0.67	0.91	0.69	0.96
Joint pain, left	0.51	0.89	0.74	0.95	0.57	0.91	0.54	0.97
Joint pain, right	0.38	0.90	0.76	0.94	0.56	0.91	0.55	0.97
Strength, left	0.50	0.90	0.60	0.95	0.54	0.91	0.55	0.97
Strength, right	0.50	0.90	0.55	0.95	0.49	0.92	0.54	0.97
Global gait	–	–	–	–	–	–	0.34	0.97

Note:

a Indicates internal consistency of remaining items if the elected item were deleted from the total score.

Abbreviation: r, Pearson’s product-moment correlation with the total score.