Future coronary artery disease (CAD) and stroke events may be better predicted by morning home blood pressure (HBP) values, according to findings published in the Journal of the American College of Cardiology.

Researchers evaluated more than 21 000 Japanese patients treated for hypertension from the HONEST study (Home blood pressure measurement with Olmesartan Naïve patients to Establish Standard Target blood pressure). Patients measured their HBP twice in the morning and twice at bedtime, in accordance with Japanese Society of Hypertension guidelines.

Researchers calculated the average of the 2 measurements at each time point, and used the average HBP over 2 days for each measurement point. If a patient experienced a stroke or CAD event, the average of HBP measurements was taken until the event occurred. HBP was measured at 1, 4, and 16 weeks and at 6, 12, 18, and 24 months.

The Cox proportional hazards model was used to investigate the relationship between on-treatment HBP or clinic blood pressure (CBP) and incidence of stroke or CAD. Researchers also performed the likelihood ratio test to determine whether the addition of HBP and/or CBP improved the goodness-of-fit of the model for stroke or CAD.

At baseline, morning HBP and CBP (systolic BP/DBP [diastolic blood pressure]) measurements were 151.2 ± 16.3 / 86.9 ± 11.7 mm Hg and 153.6 ± 19.0 / 87.1 ± 13.3 mm Hg, respectively. Mean measurements for HSBP (home systolic blood pressure) were 135.2 ± 10.9 / 79.0 ± 8.4 mm Hg, and 135.2 ± 11.5 / 77.4 ± 8.6 mm Hg for CSBP (clinic systolic blood pressure) at follow-up.

In the final analysis, 21 591 patients were included, of whom 248 experienced a stroke (n=127) or CAD (n=121) event (2.92 per 1000 patient-years and 2.78 per 1000 patient-years, respectively).

Stroke incidence was significantly higher in patients with morning HSBP measurements of 145 to <155 mm Hg (3.97 per 1000 patient-years) or ≥155 mm Hg (12.58 per 1000 patient-years) compared to those who had morning HSBP measurements of <125 mm Hg, and also in patients with CSBP measurements of 150 to <160 mm Hg (4.88 per 1000 patient-years) or ≥160 mm Hg (14.17 per 1000 patient-years) compared with <130 mm Hg.  

In patients with morning HSBP ≥155 mm Hg, the hazard ratio (HR) for stroke events was significantly higher, compared with patients whose morning HSBP measurements were <125 mm Hg (HR: 6.01; 95% confidence interval [CI]: 2.85-12.68). This trend tended to increase in patients with morning HSBP from 145 to <155 mm Hg compared with <125 mm Hg (HR: 1.90; 95% CI: 0.90-3.99; P=.091).

In patients with CSBP measurements ranging from 150 to <160 mm Hg, stroke event HRs were also significantly higher (HR: 2.00; 95% CI: 1.06-3.76) or in those with ≥160 mm Hg (HR: 5.82; 95% CI: 3.17-10.67) compared to patients with CSBP <130 mm Hg. In patients with evening HSBP measurements >145 mm Hg, the incidence and HR of stroke events were significantly higher. “These results showed that morning and evening HSBP predicted stroke events similarly to CSBP,” the authors wrote.

Similar trends were observed in CAD event incidence. In patients with patients with morning HSBP measurements of 145 to <155 mm Hg (4.15 per 1000 patient-years) CAD event incidence was significantly higher than in those who had morning HSBP <125 mm Hg and also in patients with CSBP ≥160 mm Hg compared with <130 mm Hg (8.82 per 1000 patient-years).

HRs were also significantly higher in patients with morning HSBP ≥155 mm Hg than in those with morning HSBP <125 mm Hg (HR: 6.24; 95% CI: 2.82-13.84) and tended to increase in patients with morning HSBP measurements of 145 to <155 mm Hg compared with <125 mm Hg (HR: 2.15; 95% CI: 0.98-4.71; P=.056). However, the CAD HR was only significantly higher in patients with CSBP ≥160 mm Hg (HR: 3.51; 95% CI: 1.71-7.20).

The goodness-of-fit of the model for stroke events was similar between HSBP and CSBP morning measurements (increment of likelihood ratio statistics: 33.19 vs 26.38), which the authors stated indicates both HBP and CBP are important factors in stroke prediction. However, the goodness-of-fit of the model for CAD events did not significantly improve when CSBP was introduced into the model that included morning HSBP (increment of likelihood ratio statistics: 3.80; degrees of freedom: 4; P=.434). In this case, morning HSBP may be a more important factor for predicting CAD events than CSBP.

Researchers acknowledged that their study is limited by its design: the BP target was at the physician’s discretion, combination therapy was unrestricted, and they did not include a control group. Therefore, they encouraged future randomized controlled trials to further elucidate the relationship between morning HBP values and ischemic event prediction.

Reference

Kario K, Saito I, Kushiro T, et al. Morning home blood pressure is a strong predictor of coronary artery disease. The HONEST study. J Am Coll Cardiol. 2016;67(13):1519-1527. doi: 10.1016/j.jacc.2016.01.037.