What is the clinical evidence from this study?

Study design: Cohort. Population: Hypertension (n=1199). Intervention: Nocturnal blood pressure non-dipping vs. Normal dipping. Primary outcome: Total cardiovascular events (HR 1.166, 95% CI 0.770-1.764, p=0.469).

June 16, 2021Open Access

Prognostic value of nocturnal blood pressure dipping on cardiovascular outcomes in Chinese patients with hypertension in primary care

Key Result

Nocturnal blood pressure non-dipping and reverse dipping demonstrated adverse cardiovascular prognosis in Chinese patients with hypertension, with adjusted hazard ratios for total cardiovascular events of 1.166 and 1.173, respectively.

Study Design

Type

Cohort (n=1,199)

Multicenter

Yes

Structured PICO

Does nocturnal blood pressure non-dipping or reverse dipping increase the risk of cardiovascular events in Chinese patients with hypertension?

Population

1,199 Chinese patients with hypertension undergoing ambulatory blood pressure monitoring (ABPM) in primary care, mean age 64.5 years. Excluded: non-Chinese ethnicity, secondary hypertension, known sleep disorders (e.g., obstructive sleep apnea), or lower urinary tract symptoms.

Intervention

Non-dipping (SBP-NDR >0.9 to ≤1.0), reverse dipping (SBP-NDR >1.0), or extreme dipping (SBP-NDR ≤0.8) nocturnal blood pressure patterns on 24-hour ABPM

Comparator

Normal nocturnal blood pressure dipping pattern (SBP-NDR >0.8 to ≤0.9) or traditional dippers (SBP-NDR ≤0.9)

Outcome

Total cardiovascular events (composite of acute non-fatal myocardial infarction, acute non-fatal cerebral vascular accident, congestive heart failure, transient ischemic attack, re-vascularization, CV-related hospitalization, peripheral vascular disease, end-stage renal failure, CV mortality, and new diagnosis of coronary heart disease/cerebrovascular disease) at mean 6.42 years follow-upcomposite

Nocturnal blood pressure non-dipping and reverse dipping are associated with adverse cardiovascular prognosis in Chinese patients with hypertension, highlighting the value of ABPM for risk stratification.

Main Result

Effect estimate: HR 1.166 (95% CI 0.770-1.764)

p-value: p=0.469

Limitations

Inadequate sample size and follow-up duration
Study population from hypertension referral clinics may not be generalizable to average primary care patients
Sleep quality could not be incorporated due to retrospective design
Potential missing data from private hospital admissions
Low cardiovascular mortality rate in the cohort

Abstract

Meta-analyses showed that non-dipping of nocturnal blood pressure on ambulatory blood pressure monitoring (ABPM) was associated with adverse cardiovascular prognosis. However, these prognostic studies were mainly conducted in Caucasian and Japanese populations. Whether this association applies to Chinese patients remained uninvestigated. A total of 1199 Chinese patients with hypertension undergoing ABPM between January 2012 and December 2014 were recruited retrospectively from five public hypertension referral clinics in Hong Kong. Patients were followed up for a mean 6.42 years for cardiovascular morbidity and mortality and all-cause mortality. Time to event of different dipping patterns was compared by Kaplan-Meier curves. Hazard ratios (HR) were obtained by Cox proportional hazard models with patient demographics and confounding factors adjusted in multivariate regression. A total of 163 end point events occurred in the period. Normal dipping was observed in 446 patients (37.2%), non-dipping in 490 (40.9%), reverse dipping in 161 (13.4%), and extreme dipping in 102 (8.5%). Kaplan-Meier analyses showed inferior survival in non-dippers and reverse dippers for total cardiovascular events and coronary events but not cerebrovascular events. After adjusting for confounding factors, Cox regressions showed HRs 1.166 (CI 0.770-1.764) and 1.173 (CI 0.681-2.021) in non-dippers and reverse dippers for total cardiovascular events, and HRs 1.320 (CI 0.814-2.141) and 1.476 (CI 0.783-2.784) for coronary events. Nocturnal blood pressure non-dipping, and to a greater extent reverse dipping, demonstrated adverse cardiovascular prognosis in a cohort of Chinese patients with hypertension in Hong Kong. Further focused studies on cerebrovascular events and reverse dippers were warranted to refine risk stratification.

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