Table 1.

Studies analysis autonomic dysfunction in essential hypertension. Methods of analysis include plasma noradrenaline levels, heart rate variability and muscle sympathetic nerve activity.

Author(s)	GRADE	Year published	Group BP (SBP/DBP; mmHg) and sample size (n=)	Methods	Follow-up	Main findings
Masuo et al. [12]	Moderate	2003	123 ± 8/70 ± 5 (n = 433)	Plasma noradrenaline	5 yrs	Plasma noradrenaline was a sig. determining factor of change in mean BP over 5 yrs.
Smith et al. [14]	Low	2002	N: 129 ± 1.7/82 ± 2.1 (n = 12) WH: 157 ± 4.3/95 ± 1.1 (n = 12) H: 155 ± 3.4/93 ± 1.4 (n = 12)	MSNA	–	MSNA was greater in white coat hypertensive than normotensive subjects, and greater still in the hypertensive group.
Singh et al. [13]	Moderate	1998	N: 120 ± 0.5/77 ± 0.3 (n = 1570) H: 143 ± 0.7/89 ± 0.5 (n = 472)	HRV	4 yrs	HRV is reduced in those with hypertension. Lower HRV is associated with the development of hypertension.
Grassi et al. [15]	Low	1998	N: 134 ± 3.1/79 ± 2.9 (n = 10) H: 138 ± 3.2/96.8 ± 1.9 (n = 10)	MSNA	–	MSNA was sig. greater in hypertensive subjects.

HRV = heart rate variability; MSNA = muscle sympathetic nerve activity; BP = blood pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; N = normotensive group; H = hypertensive group; WH = white-coat hypertensive group. WH was diagnosed as a sustained clinic BP of ≥140/90 mmHg with a daytime ambulatory BP of <130/80 mmHg. GRADE: The Grades of Recommendation, Assessment, Development and Evaluation.