In Lupus, Keep BP Below 130/80 Save

Blood pressure should be maintained at a level below 130/80 mm Hg in all patients with lupus to lessen their likelihood of atherosclerotic vascular events, Canadian researchers asserted.

In a study of patients enrolled in the University of Toronto Lupus Clinic, those whose adjusted mean blood pressure was in the range of 130-139/80-89 mm Hg during the first 2 years after enrollment had a 73% higher risk of an atherosclerotic vascular event compared with those whose blood pressure was below the 130/80 mm Hg threshold, according to Murray Urowitz and colleagues of the University of Toronto.

That reflected a hazard ratio of 1.73 (95% CI 1.13-2.69, P=0.011) after adjustment for traditional and lupus-related risk factors, they reported online in Annals of the Rheumatic Diseases.

In 2018, the American College of Cardiology/American Heart Association published revised guidelines on the management of hypertension in adults, lowering the threshold for hypertension from 140/90 to 130/80 mm Hg, with levels from 130-139/80-89 mm Hg now being considered stage 1 hypertension and 140/90 mm Hg being stage 2.

And despite the inclusion of various risk groups in the guideline, there were no recommendations for patients with connective tissue diseases such as systemic lupus erythematosus -- who have a five-fold increased risk over their lifetime for atherosclerotic vascular events such as angina, acute MI, cerebrovascular events, and revascularization procedures.

Moreover, traditional cardiovascular risk calculators typically underestimate risks among patients with lupus because they don't account for the disease-related risks and usually are designed for use in individuals older than age 40. Accordingly, treatment of hypertension in lupus patients may be unnecessarily delayed, worsening their risks and prognosis.

"Furthermore, hypertension has been related to every surrogate endpoint for atherosclerosis, including impaired endothelial function, arterial stiffness, increased carotid intima-media thickness and plaque formation, coronary artery calcification, and angiographically proven coronary artery disease," the researchers noted.

Therefore, to help provide guidance on hypertension for clinicians caring for patients with lupus, Urowitz and colleagues analyzed data from their cohort, which has enrolled more than 2,000 patients since 1970. Their analysis included 1,532 patients who had at least 2 years follow-up and who had not previously had an atherosclerotic event.

Almost 90% were female. Mean age was 36 and disease duration averaged 6 years. Adjusted mean blood pressure over the first 2 years of follow-up was above 140/90 mm Hg in 10.1%, from 130-139/80-89 mm Hg in 20.6%, and below 130/80 mm Hg in the remaining 69.3%. These adjusted blood pressures were based on an average of 6.3 measurements over the 2 years, which accounted for the fluctuations in blood pressure that are typical in lupus.

After a mean follow-up of 10.8 years, there were 124 atherosclerotic vascular events, including 20 cardiovascular deaths. Other events commonly reported included new-onset angina in 40 patients, acute MI in 23, and cerebrovascular events in 18.

The prevalence of atherosclerotic events was 20.6% in the group whose blood pressure was above 140/90 mm Hg, 13% in those whose levels were 130-139/80-89 mm Hg, and 4.8% in those below 130/80 mm Hg, while incidence rates were 18.9, 11.5, and 4.5 per 1,000 patient-years, respectively.

The Kaplan-Meier curve for atherosclerotic events over time showed statistically significant differences between normotensive patients and those with stage 1 hypertension and also between stage 1 and stage 2.

On a multivariate analysis, factors other than stage 1 hypertension that were associated with atherosclerotic vascular events included:

• Use of anticoagulants or antiplatelet agents: HR 3.34 (95% CI 2.25-4.94, P<0.0001)
• Smoking: HR 1.86 (95% CI 1.17-2.96, P=0.0084)
• Glucocorticoid use: HR 1.76 (95% CI 1.19-2.60, P=0.0043)
• Disease Activity Index: HR 1.10 (95% CI 1.06-1.15, P<0.0001)

A sensitivity analysis that excluded 30 patients with end-stage renal disease had similar results as the primary analysis.

"The findings of the present study support that the target blood pressure should be less than 130/80 mm Hg in all patients with lupus in order to minimize their cardiovascular risk," Urowitz and colleagues concluded.

They also questioned whether further lowering of blood pressure could be beneficial, and referred to a population-wide study from Sweden that included 187,000 patients with type 2 diabetes. In that study, the lowest risk for nonfatal atherosclerotic events was seen with blood pressures of 110-119 mm Hg systolic, but that level was associated with an increase in risk for heart failure of 20% and for all-cause mortality of 28%.

"Based on these data, targeting lower levels of blood pressure might be unsafe in certain patients with lupus (e.g., with prior heart disease or heart failure)," they cautioned.

The University of Toronto Lupus Clinic is supported by the University Health Network, Lou & Marissa Rocca, Mark & Diana Bozzo, and the Lupus Foundation of Ontario.

The authors disclosed no relevant relationships with industry.