Association between Cumulative Blood Pressure and Long-Term Risk of Cardiovascular Disease: Findings from the 26-Year Chinese Multi-Provincial Cohort Study-Beijing Project
Hypertension is a critical risk factor for cardiovascular disease (CVD), which remains a leading cause of morbidity and mortality worldwide. In China, high systolic blood pressure (SBP) accounted for 2.54 million deaths in 2017, with 95.7% of these deaths attributed to CVD. While baseline blood pressure (BP) levels are known to predict CVD risk, recent research has highlighted the importance of cumulative BP, which incorporates both the level and duration of BP exposure. This study aimed to investigate the association between 15-year cumulative BP levels and the long-term risk of CVD, and to determine whether this association is independent of BP levels measured at a single examination.
The study utilized data from the Chinese Multi-Provincial Cohort Study-Beijing Project, a prospective cohort study that initially enrolled 4,151 participants in Beijing. Participants were aged 35 to 64 years and free of CVD at baseline in 1992. They were invited for follow-up examinations in 2002 and 2007. This analysis included 2,429 participants who attended both the 1992 and 2007 examinations and were free of CVD in 2007. These participants were followed up until 2018 for the development of CVD events, including coronary heart disease and stroke.
Cumulative BP was calculated by summing the product of the mean BP for each pair of consecutive examinations and the time interval between these examinations. The formula used was: Cumulative BP = [(BP1 + BP2)/2 × time1–2 + (BP2 + BP3)/2 × time2–3], where BP1, BP2, and BP3 were BP measurements at years 0, 10, and 15, respectively, and time1–2 and time2–3 were the time intervals between these examinations. For participants who missed the 2002 examination, cumulative BP was calculated as (BP1 + BP3)/2 × time1–3.
During the follow-up period from 2007 to 2018, 207 CVD events were recorded. Participants with higher levels of cumulative SBP or diastolic blood pressure (DBP) exhibited a significantly higher incidence rate of CVD. The Kaplan-Meier curves demonstrated that the risk of CVD increased progressively with higher quartiles of cumulative SBP and DBP (log-rank P < 0.001). The incidence rates of CVD per 100,000 person-years were 357.4, 505.0, 1,054.4, and 1,819.6 for the first to fourth quartiles of cumulative SBP, respectively. Similarly, the rates were 354.7, 693.4, 1,102.3, and 1,556.7 for the first to fourth quartiles of cumulative DBP, respectively.
After adjusting for classical risk factors, including age, sex, smoking status, diabetes, levels of high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), and the use of antihypertensive and lipid-lowering drugs, the hazard ratios (HRs) for CVD in the second to fourth quartiles of cumulative SBP were 1.17, 2.10, and 3.27, respectively, compared to the first quartile. For cumulative DBP, the HRs were 1.61, 2.36, and 2.78 for the second to fourth quartiles, respectively. Further adjustment for SBP or DBP levels in 2007 attenuated these associations, but they remained significant or borderline significant for the third and fourth quartiles of cumulative SBP and DBP.
The study also conducted combined group analyses to examine the independent effect of cumulative BP levels. Participants were categorized into four groups based on whether their 15-year cumulative BP levels and BP levels in 2007 were above or below the median. The results showed that high cumulative BP levels were associated with a significantly increased risk of CVD, regardless of whether the BP levels in 2007 were high or low. For example, participants with high cumulative SBP and low SBP in 2007 had an HR of 2.01 for CVD, while those with high cumulative SBP and high SBP in 2007 had an HR of 2.63, compared to the reference group with low cumulative SBP and low SBP in 2007.
The findings of this study underscore the importance of cumulative BP in predicting long-term CVD risk. The results suggest that maintaining SBP and DBP levels below 130 mmHg and 80 mmHg, respectively, is crucial for cardiovascular health. Even moderate elevations in BP over time can significantly increase the risk of CVD, independent of BP levels at a single examination. This highlights the need for early identification and management of elevated BP to prevent future cardiovascular events.
The study also provides valuable insights into the level of cumulative BP that significantly increases CVD risk. A 15-year cumulative SBP level higher than 1,970.8 mmHg·year, equivalent to maintaining an average SBP of 131 mmHg or above, was associated with a significantly increased risk of CVD. Similarly, a cumulative DBP level higher than 1,239.9 mmHg·year, equivalent to maintaining an average DBP of 83 mmHg or above, was associated with increased CVD risk.
These findings have important implications for clinical practice and public health. They suggest that cumulative BP should be considered in addition to single BP measurements when assessing cardiovascular risk. Health care providers should pay attention to patients’ long-term BP exposure and implement lifestyle interventions or pharmacological treatments as needed to maintain BP within the optimal range.
In conclusion, this study demonstrates that elevated cumulative BP levels are independently associated with an increased risk of CVD in the Chinese population. The findings emphasize the importance of maintaining BP levels below 130/80 mmHg over the long term to reduce cardiovascular risk. Cumulative BP provides valuable information for identifying individuals at high risk of CVD and guiding preventive strategies. Future research should explore the effectiveness of interventions targeting cumulative BP in reducing CVD incidence and mortality.
doi.org/10.1097/CM9.0000000000001383
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