May Measurement Month 2021: an analysis of blood pressure screening results from China

Abstract

We reported findings from participants screened during the May Measurement Month 2021 in China, which aimed to raise awareness of raised blood pressure (BP), and to investigate the risk factors of BP. The study participants were adults (≥18 years), ideally in whom BP had not been measured in the previous year. Blood pressure was measured three times consecutively with 1 min intervals in the sitting position, using a validated upper-arm cuff automated BP monitor (Omron HEM-7081IT), and transmitted to a central cloud database via a smartphone app. The measurement was performed in 218 844 participants in 183 sites across 31 China provinces. The mean (standard deviation) age was 47.0 (15.7) years, and 51.8% (n = 113 466) were women. The mean systolic/diastolic BP was 120.2/77.5 mmHg. Among 57 178 (26.1%) participants with hypertension, the awareness, treatment, and control rates of hypertension were 30.4% (n = 17 354), 28.7% (n = 16 369), and 17.1% (n = 9743), respectively. After adjustment for age, sex, and use of antihypertensive medication, both systolic and diastolic BP were significantly (P ≤ 0.01) higher in current smokers (n = 22 344, +0.4/+0.7 mmHg) and with moderate (n = 4780, +1.4/+4.2 mmHg) or daily alcohol intake (n = 2427, +1.3/+2.5 mmHg). Blood pressure was lower in those reporting regular exercise (n = 32 328, −2.2/−1.4 mmHg). In addition, individuals with previous COVID-19 vaccination had lower systolic and diastolic BP (n = 88 945, −1.8/−1.5 mmHg, P ≤ 0.001). In conclusion, our study showed that long-term large-scale screening for hypertension is feasible, and there is a strong association between BP and major lifestyle factors.

Introduction

China actively participated in the worldwide May Measurement Month (MMM) campaign initiated by the International Society of Hypertension for hypertension screening since it was initially started in 2017 in order to raised awareness of raised blood pressure (BP).^1–3 Blood pressure was measured in 125 236, 288 342, and 238 387 participants in 2017,¹ 2018,² and 2019,³ respectively, with a proportion of hypertension being 25.7%,¹ 29.8%,² and 27.8%,³ respectively. Because of the outbreak of COVID-19 at the beginning of 2020, the worldwide campaign was paused during 2020. However, the campaign continued in China in the fall of 2020, and achieved a total of 97 784 screened participants. The data obtained in that year have yet to be published. The worldwide campaign restarted in May 2021, and we measured BP as usual in spring and summer in a relatively large number of participants. In addition, we collected information on infections of and vaccinations for COVID-19 during the campaign. In the present analysis, we report the data obtained in the MMM21 project in China.

Methods

The screening campaign in China strictly followed the international MMM protocol,⁴ and was conducted from May–August 2021, with the time of the campaign extended to allow flexibility for local COVID-19 measures. In total, 183 sites were set up across 31 provinces in China. The Chinese Hypertension League formed a team of experts from various parts of China for the recruitment and training of volunteer investigators, and the organization of measurement work during the whole period of the campaign. The measurement sites were mostly inside hospitals or community health centres but usually located in a public area instead of doctors’ offices for routine clinical service.

The study participants were adults (≥18 years), ideally in whom BP had not been measured in the previous year. Blood pressure was measured three times consecutively with 1 min intervals in the sitting position, using a validated upper-arm cuff automated BP monitor (HEM-7081IT, Omron Healthcare, Kyoto, Japan) with an appropriately sized cuff (standard and large cuffs for an upper arm circumference 22–32 cm and 32–42 cm, respectively), and transmitted to a central database via a smartphone app. A short questionnaire was administered to collect information on medical history, lifestyle, use of medications, and infection and vaccination for COVID-19.

Hypertension was defined as in the global project: systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg and/or on treatment for hypertension. In patients on antihypertensive medication, control of hypertension was defined as on antihypertensive medication and systolic BP < 140 and diastolic BP < 90 mmHg.

The Ethics Committee of Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China approved the study. All study participants gave informed written consent.

Data management and statistical analysis were performed centrally by the MMM project team, and multiple imputation was performed to impute the mean of readings two and three where this was missing.⁵

Results

In total, 218 844 participants were screened during MMM21. The mean (standard deviation) age of participants was 47.0 (15.7) years and included 51.8% (n = 113 466) women. Overall, 16 393 (7.5%) participants were on antihypertensive medication, 5473 (2.5%) on aspirin, and 6446 (2.9%) on a statin. A total of 536 (0.2%) participants reported a previous positive COVID-19 test, and 88 945 (40.6%) had one or more previous COVID-19 vaccinations at the time of BP measurement.

After multiple imputation, of all 218 844 participants, the proportion with hypertension was 26.1% (n = 57 178). Of the 57 178 participants with hypertension, the awareness, treatment, and control rates of hypertension were 30.4% (n = 17 354), 28.7% (n = 16 393), and 17.1% (n = 9766), respectively (Table 1). Of the 16 393 patients on antihypertensive medication, 40.4% (n = 6627) had uncontrolled BP. Of the 202 451 individuals not on antihypertensive medication, 20.1% (n = 40 785) were hypertensive.

Table 1.

Total participants and proportions with hypertension, awareness, on medication, and with controlled blood pressure

Total participants	Number (%) with hypertension	Number (%) of hypertensives aware	Number (%) of hypertensives on medication	Number (%) of those on medication with controlled blood pressure	Number (%) of all hypertensives with controlled blood pressure
218 844	57 178 (26.1)	17 354 (30.4)	16 393 (28.7)	9766 (59.6)	9766 (17.1)

After adjustment for age, sex, and use of antihypertensive medication, both systolic and diastolic BP were significantly (P ≤ 0.01) higher in current smokers (n = 22 344, +0.4/+0.7 mmHg) compared to non-smokers, and moderate (n = 4780, +1.4/+4.2 mmHg) or daily alcohol intake (n = 2427, +1.3/+2.5 mmHg) compared to those who drank rarely. Blood pressure was lower in those meeting the WHO guidelines on physical activity of 150 min of moderate exercise or 75 min of more vigorous exercise per week (n = 32 328, −2.2/−1.4 mmHg) compared to those who did not. Compared to participants with no formal education, participants with over 12 years of education (n = 49 650) had lower systolic and diastolic BP (−2.1/−2.4 mmHg, P ≤ 0.001). Interestingly, individuals with previous COVID-19 vaccination (n = 88 945) had lower systolic and diastolic BP (−1.8/−1.5 mmHg, P ≤ 0.001, Figure 1), but there was no association of BP with those reporting a previous positive COVID-19 test.

Figure 1.

Difference in mean blood pressure in individuals with a previous COVID-19 test or vaccination, compared to those without, from linear regression models, adjusted for age, sex, and antihypertensive medication.

Discussion

The proportion of hypertension in 2021 (26.1%) was similar to the results of the MMM campaign in China in the past several years (25.7–29.8%).^1–3 The rates of awareness (30.4%), treatment (28.7%), and control of hypertension (17.1%), however, were lower in 2021 than in 2018 (62.3%, 57.3%, and 35.9%, respectively) and 2019 (51.5%, 48.4%, and 29.1%, respectively). The decline in these rates was quite substantial and might be partly attributable to the COVID-19 related activities.

In China, the community health centres are responsible for the detection and management of hypertension on the population level.⁶ The tasks of these community health centres had to shift to the prevention and control of COVID-19 from 2020–22. With the changes in the strategies in the management of COVID-19 in China in 2023, the community health centres may resume the routine work, including management of hypertension. The situation might then change in a positive direction.

The results of our study showed that BP was lower in participants who received than those who did not receive COVID-19 vaccination. This finding is in contrast to the results of a previous meta-analysis that reported raised BP after COVID-19 vaccination.⁷ This discrepancy is unexplained but may relate to unmeasured confounding. It is possible that many patients with previously or newly identified hypertension did not receive vaccination for safety reasons, although there is no evidence of any safety concern on COVID-19 vaccination in patients with hypertension.

A main limitation of our study was that the study participants were from an opportunistic screening rather than a randomly sampled population and so estimates are not nationally representative. However, the campaign was conducted in a large number of measurement sites across almost all China provinces and provided important information on the management of hypertension in China and the association between BP and various major lifestyle factors, such as cigarette smoking, moderate to heavy alcohol consumption, and regular exercise.

In conclusion, these data showed that long-term large-scale screening for hypertension is feasible and should therefore continue for a better control of hypertension in the populous country of China.

Funding

Y.L. and J.-G.W. were financially supported by grants from the National Natural Science Foundation of China (grants 82070432, 82070435, and 82270469), and Ministry of Science and Technology (grants 2018YFC1704902 and 2022YFC3601302), Beijing, and from the Shanghai Municipal Commissions of Science and Technology (grant 19DZ2340200), and Health (grant 2022LJ022), Shanghai, China.

Data availability

The data underlying this article cannot be shared publicly for the privacy of individuals that participated in the study. The data will be shared on reasonable request to the corresponding author.