To the Editor: Stroke is a major cause of death and long-term serious disability in adults worldwide. Hypertension is the most important modifiable risk factor for primary and secondary prevention of stroke.[1] Even a modest reduction in clinical blood pressure (BP) of approximately 10/5 mmHg is associated with a significant 30% risk reduction of adverse clinical events. While clinical evidence strongly advocated the effectiveness of managing BP to reduce adverse outcomes after ischemic stroke,[2] the management and control of BP in ischemic stroke patients after discharge remain poor.

BP management of patients after discharge mainly involves two aspects: physician intervention and self-management. Self-management has gained widespread use in other chronic conditions, such as diabetes.[3] Self-BP management has been studied as a way to enhance BP control in hypertensive patients and those at high risk of cardiovascular events.[4] Previous studies have examined the effects of self-BP management on lowering BP levels,[5,6] but few have examined the effects on clinical outcomes, and no clinical trials with sufficient statistical power have been published to explore the association between self-BP monitoring and clinical outcomes in ischemic stroke patients.

The China Antihypertensive Trial in Acute Ischemic Stroke (CATIS)[7] was a multicenter randomized controlled trial designed to test the effect of lowering BP immediately initiated within the first 48 h after acute ischemic stroke onset and lasted for 14 days or duration of hospitalization on death or major disability. The randomization schedules were generated using PROC PLAN in Statistics Analysis System (SAS) and concealed until an eligible participant was ready for enrollment. Study participants were followed-up in-person at 3 months and 12 months after stroke onset. Based on the CATIS trial, we focused on self-BP management for ischemic stroke patients after discharge and analyzed the relationship between whether the patients measured BP often after discharge and the clinical outcomes in ischemic stroke patients.

CATIS was registered at clinicaltrials.gov (https://www.clinicaltrials.gov; No. NCT01840072) and our study was approved by the Ethics Committee of Soochow University in China (No. 2007IRB1). Written consent was obtained from all study participants or their immediate family members. Study participants were recruited from August 2009 to May 2013, and finally 4071 participants were included. After excluding 96 participants lost to follow up at 3-month and 54 participants who lacked the data of BP measurement, 3921 participants were included at the 3-month follow-up analysis. And after excluding 208 participants lost to follow-up at 1-year and 13 participants who lacked the data of BP measurement, 3850 participants were included at the l-year follow-up analysis.

Baseline data on demographic characteristics, socioeconomic status, and disease history were collected using a standard questionnaire at the time of enrollment. Ischemic stroke was classified as large artery atherosclerosis (thrombotic), cardiac embolism (embolic), or small artery occlusion lacunae (lacunar) according to the symptoms and imaging data of the patients. Stroke severity was assessed by trained neurologists at baseline and discharge using the National Institutes of Health Stroke Scale (NIHSS). BP was measured at baseline, 14 days after stroke or discharge, and at 3 months and 12 months. At the 3-month follow-up, participants who measured BP often after discharge were defined as having a “yes” answer to the question: “Did you measure your BP often after discharge (at least once a week)?” The use of antihypertensive medication after discharge was defined according to the following question: “Have you been taking antihypertensive medication after discharge?” Based on the patient’s answer, the investigators chose the best option: continuous medication, intermittent medication, or no medication.

The primary study outcome was a composite outcome of death and major disability at 3 months and 12 months after stroke onset. Scores on the modified Rankin Scale (mRS) ranged from 0 to 6, with a score of 0 indicating no symptoms, a score of 5 indicating severe disability, and a score of 6 indicating death. Major disability was defined as a score of 3–5 on the mRS. The secondary outcomes included death, vascular events, and the composite outcome of death and vascular events. Death certificates were obtained for deceased participants, and hospital data were abstracted for all vascular events.

All participants were divided into two groups (“No” and “Yes”) according to whether the patients measured BP often after discharge. Logistic regression models were used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for the association between whether the participants measured BP often after discharge and the composite outcome of death and major disability. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% CIs for the association between whether the participants measured BP often after discharge and death, vascular events, and the composite outcome of death and vascular events. In this study, the statistical powers were over 90% for all study outcomes, and two-tailed P <0.05 were considered to be statistically significant. All analyses were conducted using SAS statistical software (version 9.4, Cary, NC, USA).

The baseline characteristics of the two groups are presented in Supplementary Table 1, https://links.lww.com/CM9/B966. A total of 3921 patients (2512 men and 1409 women) were included in this analysis, and the average age was 62.39 ± 10.92 years. Of these, 2037 (2037/3921, 51.95%) patients who did not measure BP often after discharge were classified into the “No” group, and 1884 (1884/3921, 48.05%) patients who measured BP often after discharge were classified into the “Yes” group.

Within the duration of the 3-month follow-up, a total of 950 patients (950/3921, 24.23%) developed the composite outcome of death and major disability, 70 patients (70/3921, 1.79%) died, 97 patients (97/3921, 2.47%) experienced vascular events, and 134 patients (134/3921, 3.42%) developed the composite outcome of death and vascular events. Within the duration of the 12-month follow-up, a total of 806 patients (806/3850, 20.94%) developed the composite outcome of death and major disability, 172 patients (172/3850, 4.47%) died, 216 patients (216/3850, 5.61%) experienced vascular events, and 306 patients (306/3850, 7.95%) developed the composite outcome of death and vascular events. The systolic blood pressure (SBP) level at the 3-month follow-up was 142.1 ± 12.8 mmHg in the “No” group and 139.3 ± 11.5 mmHg in the “Yes” group (χ2 = 65.08, P <0.001); the SBP level at the 12-month follow-up was 140.3 ± 11.8 mmHg in the “No” group and 138.7 ± 10.9 mmHg in the “Yes” group (χ2 = 20.88, P <0.001) [Supplementary Figure 1, https://links.lww.com/CM9/B966]. The number of patients who continuously used antihypertensive medication after discharge was 889 (889/2037, 43.64%) in the “No” group and 1489 (1489/1884, 79.03%) in the “Yes” group. The number of patients who intermittently or did not use antihypertensive medication after discharge was 1148 (1148/2037, 56.36%) in the “No” group and 395 (395/1884, 20.97%) in the “Yes” group (χ2 = 513.67, P <0.001) [Supplementary Figure 2, https://links.lww.com/CM9/B966].

Patients in the “Yes” group had lower risks of primary and secondary outcomes after adjusting for age, sex, education level, discharge NIHSS score, and other important covariates mentioned in Model 2. Compared with the “No” group, the multivariable-adjusted ORs associated with the “Yes” group were 0.68 (95% CI, 0.56–0.84; P <0.001) for the primary outcome at 3-month and 0.65 (95% CI, 0.53–0.80; P <0.001) for the primary outcome at 12-month; the multivariable-adjusted HRs were 0.01 (95% CI, 0.01–0.07; P <0.001) for death, 0.46 (95% CI, 0.29–0.72; P = 0.001) for vascular events, and 0.28 (95% CI, 0.18–0.43; P <0.001) for the composite outcome of death and vascular events at 3-month; 0.25 (95% CI, 0.17–0.37; P <0.001) for death, 0.68 (95% CI, 0.50–0.91; P = 0.010) for vascular events, and 0.50 (95% CI, 0.39–0.65; P <0.001) for the composite outcome of death and vascular events at 12-month [Table 1]. In the subgroup analysis, statistical tests for interactions between whether the participants measured BP often after discharge and discharge SBP, the use of antihypertensive medication on primary outcome, and other interested variable were all non-significant (all P for interaction >0.05) [Supplementary Tables 2, 3, and 4, https://links.lww.com/CM9/B966].