Deep breathing: A simple test for white coat effect detection in primary care

Figures & data

Figure 1. Flow chart of the Deep Breath Test (DBT) in the white coat hypertension (WCH) trial.

Figure 2. Receiver-operator characteristic (ROC) curve confronting sensitivity and specificity of the Deep Breath Test (DBT) resulting from the trial.

Table I. Relevant demographic data for the study participants (n = 214).

	Group A, n = 106		Group B, n = 108		p
	n	%	n	%
Gender
Male	44	41.5	45	41.7	0.981
Female	62	58.5	63	58.3
Age (median; IQR)	64	53–72	65	59–72	0.502
Smoker
Yes	15	14.3	18	16.7	0.839
Never	67	63.8	69	63.9
Former	23	21.9	21	19.4
Alcohol consumption
Yes	38	36.9	31	29.2	0.351
Former	54	52.4	58	54.7
Never	11	10.7	17	16.0

IQR, interqartile range; p-value for χ² test (nominal data) and Mann–Whitney test (interval data).

Table II. Blood pressure results in group A (n = 94).

Blood pressure (mmHg)	Statistics
	Mean	SD	df	F	η^2	p
Systolic
Daytime, ABPM	136	13.9	3.326	55.635	0.527	< 0.001
5-min, office	160	16.0
5-min, DB	146	18.0
15-min, office	151	16.1
15-min, DB	145	17.1
Diastolic
Daytime, ABPM	84	10.9	3.200	24.991	0.333	< 0.001
5-min, office	93	10.3
5-min, DB	89	12.3
15-min, office	93	12.1
15-min, DB	89	12.2

SD, standard deviation; df, degrees of freedom, p–value for analysis of variance (repeated measurements); η², effect measure of F-ratio.

Table III. Blood pressure differences between hyperreactors and non-hyperreactors according to the five measurements (in mmHg).

Blood pressure	Statistics
	Hyperreactors		Non-hyperreactors		Absolute difference	t	df	p
	Mean	SD	Mean	SD
Systolic
Daytime average, ABPM	132.4	12.4	146.6	13.0	− 14.2	− 4.868	103	< 0.001
5-min office	163.4	14.8	151.8	15.4	11.6	3.344	103	0.001
5-min DB	147.4	18.0	141.8	14.9	5.6	1.377	102	0.172
15-min office	153.5	19.0	152.0	12.3	1.5	0.350	95	0.727
− 15-min DB	143.4	19.1	142.1	15.0	1.3	0.272	92	0.786
Diastolic
Daytime average, ABPM	78.6	9.2	88.7	10.1	− 10.1	− 5.371	103	< 0.001
5-min office	96.2	10.0	89.3	9.6	6.9	3.652	103	< 0.001
5-min DB	90.6	12.3	86.2	11.3	4.4	1.883	102	0.063
15-min office	95.7	12.5	89.6	10.1	6.1	2.512	95	0.014
15-min DB	90.2	10.9	85.7	12.3	4.5	1.884	92	0.063

SD, standard deviation; Student’s t-test; df, degrees of freedom; p-value for Student’s t-test (independent samples).