Development, Reliability, and Validity of the Home Blood Pressure Monitoring Adherence Scale for Patients with Chronic Kidney Disease

Figures & data

Table 1 Participant Characteristics (n = 436)

Characteristics	n	%	Characteristics	n	%
Sex			Office systolic blood pressure
Male	284	65.1	100~139mmHg	158	36.2
Female	152	34.9	140~159 mmHg	163	37.4
Age (years)			160~179 mmHg	86	19.7
20~44	124	28.4	180~ 247mmHg	29	6.7
45~59	153	35.1	Office diastolic blood pressure
60~74	138	31.7	60~ 89 mmHg	252	57.8
75~87	21	4.8	90~ 99 mmHg	97	22.3
Education			100~109 mmHg	59	13.5
Primary school  or below	114	26.1	110~ 135mmHg	28	6.4
Junior school	127	29.1	Number of antihypertensive drugs
High school	111	25.5	0	78	17.9
College or above	84	19.3	1	110	25.2
Occupation status			2	117	26.8
Unemployed	190	43.6	3~5	131	30.1
Employed	139	31.9
Retired	107	24.5
Stage of CKD*
CKD-1	17	3.9
CKD-2	13	3.0
CKD-3a/CKD-3b	21	4.8
CKD-4	9	2.1
CKD-5 (non-dialysis)	32	7.3
Haemodialysis	323	74.1
Peritoneal dialysis	21	4.8

Note: *The stage of chronic kidney disease (CKD) was stratified with estimated glomerular filtration rate (eGFR) according to the Guidelines of Kidney Disease: Improving Global Outcomes.

Table 2 Frequency Distribution for Each Option of Each Item (n/%)

	Training Dataset (n=218)
Item	Never	Occasionally	Sometimes	Often	Always
1. I measure my blood pressure at home in the morning.	56 (25.7)	45 (20.6)	18 (8.3)	51 (23.4)	48 (22.0)
2. I measure my blood pressure at home in the evening.	68 (31.2)	57 (26.1)	16 (7.3)	40 (18.3)	37 (17.0)
3. When I feel discomfort (such as dizziness, headache, and stiff neck), I will measure my blood pressure.	34 (15.6)	19 (8.7)	14 (6.4)	92 (42.2)	59 (27.1)
4. I will take a 5-minute break and then measure my blood pressure.	48 (22.0)	29 (13.3)	27 (12.4)	69 (31.7)	45 (20.6)
5. I will take the second measurement at an interval of 1–2 minutes.	79 (36.2)	79 (36.2)	21 (9.6)	21 (9.6)	18 (8.3)
6. I was able to adjust my blood pressure measurement as advised by the medical personnel.	34 (15.6)	19 (8.7)	32 (14.7)	96 (44.0)	37 (17.0)
7. I monitor my blood pressure at home even when I am busy.	40 (18.3)	52 (23.9)	22 (10.1)	73 (33.5)	31 (14.2)
8. When my blood pressure is well controlled, I will still monitor my blood pressure at home.	43 (19.7)	50 (22.9)	19 (8.7)	71 (32.6)	35 (16.1)

Table 3 Results of Item Analysis (n = 218)

Item		S	CV	CR	Item–Total Correlation	CITC	Cronbach’s α if Item is Deleted^#	Communalities	Factor Loading	Substandard Quantity
1	2.95	1.535	0.520	27.267**	0.831**	0.763	0.892	0.693	0.832	0
2	2.64	1.500	0.568	19.145**	0.779**	0.696	0.898	0.595	0.771	0
3	3.56	1.381	0.388	9.932**	0.706**	0.613	0.904	0.489	0.699	0
4	3.16	1.463	0.463	19.312**	0.790**	0.712	0.896	0.613	0.783	0
5	2.17	1.251	0.576	9.016**	0.591**	0.486	0.914	0.326	0.571	1
6	3.38	1.301	0.385	16.587**	0.841**	0.788	0.890	0.723	0.850	0
7	3.01	1.373	0.456	20.174**	0.843**	0.787	0.890	0.734	0.857	0
8	3.02	1.412	0.468	23.976**	0.856**	0.802	0.888	0.753	0.868	0

Notes: ^#Cronbach’s α for the eight items was 0.922; **p<0.001.

Abbreviations: CV, coefficient of variation; CR, critical ratio; CITC, corrected item–total correlation.

Table 4 Total Variance Explained

Component	Initial Eigenvalues			Extracted Sum of Squared Loadings
	Total	Variance (%)	Cumulative (%)	Total	Variance (%)	Cumulative (%)
1	4.925	61.568	61.568	4.925	61.568	61.568
2	0.874	10.921	72.489
3	0.658	8.227	80.715
4	0.551	6.883	87.598
5	0.375	4.689	92.287
6	0.257	3.211	95.498
7	0.234	2.921	98.419
8	0.126	1.581	100

Figure 1 Confirmatory factor analysis model.

Table 5 Correlation Analysis Between Items and Between Each Item and the Total

Variables	Item 1	Item 2	Item 3	Item 4	Item 5	Item 6	Item 7	Item 8
Item 1	1
Item 2	0.736**	1
Item 3	0.513**	0.476**	1
Item 4	0.618**	0.544**	0.472**	1
Item 5	0.330**	0.404**	0.314**	0.583**	1
Item 6	0.601**	0.495**	0.560**	0.563**	0.390**	1
Item 7	0.663**	0.528**	0.514**	0.575**	0.403**	0.742**	1
Item 8	0.746**	0.552**	0.467**	0.626**	0.430**	0.703**	0.820**	1
Total	0.844**	0.774**	0.688**	0.801**	0.619**	0.800**	0.838**	0.857**

Note: **p<0.001.

Table 6 The Scores of HBPMAS for Non-Dialysis and Dialysis Patients

		Non-Dialysis Patients (n=92)			Dialysis Patients (n=344)			All Patients (n=436)
Item	Grading Range	Score Range		S	Score Range		S	Score Range		S
Item 1	1~5	1~5	3.18	1.33	1~5	3.15	1.54	1~5	3.16	1.50
Item 2	1~5	1~5	2.47	1.31	1~5	2.91	1.55	1~5	2.82	1.51
Item 3	1~5	1~5	3.45	1.35	1~5	3.63	1.33	1~5	3.59	1.33
Item 4	1~5	1~5	2.98	1.56	1~5	3.32	1.36	1~5	3.25	1.41
Item 5	1~5	1~5	2.13	1.34	1~5	2.38	1.29	1~5	2.33	1.30
Item 6	1~5	1~5	3.60	1.32	1~5	3.44	1.20	1~5	3.47	1.22
Item 7	1~5	1~5	3.27	1.42	1~5	3.17	1.34	1~5	3.19	1.36
Item 8	1~5	1~5	3.34	1.41	1~5	3.17	1.38	1~5	3.20	1.39
Total	8~40	8~40	24.41	8.33	8~40	25.17	8.69	8~40	25.01	8.61

Abbreviation: HBPMAS, Home Blood Pressure Monitoring Adherence Scale.