Absolute benefit from BP-lowering therapy greatest in high-risk patients

A new study from the Blood Pressure Lowering Treatment Trialists’ Collaboration demonstrates that lowering BP is associated with similar relative benefits at all levels of baseline CV risk, but provides progressive, greater absolute risk reductions within increasing baseline risk.

The data suggest that a risk-based approach is effective for making decisions regarding BP-lowering treatment, the researchers wrote.

The analysis included data from 11 trials for which researchers randomly assigned participants to receive BP-lowering drugs or placebo, or to more- or less-intensive BP-lowering treatment regimens. All studies included at least 1,000 patient-years of planned follow-up. Evaluated BP treatment types included ACE inhibitors, calcium channel blockers and diuretics. The primary outcome for the meta-analysis was major CV events, including stroke, MI, HF or CV-related death.

Across the trials, a total of 67,475 patients were randomized into 26 groups, with evaluable data for 51,917 participants. The mean estimated absolute 5-year risk for CV events was 11.7%. Patients were categorized according to 5-year risk for CV events at baseline according to a risk-prediction equation developed using data from the placebo groups of 10 included trials: <11%, 11%-15%, 15%-21% and >21% risk. Researchers estimated baseline 5-year CV risk levels at 6% for the <11% group 12.1% for the 11%-15% group, 17.7% for the 15%-21% group and 26.8% for the >21% group.

CV events occurred in 8% of patients during a median of 4 years of follow-up. BP-lowering therapy was associated with a reduction in CV event risk by 18% in the <11% group; 15% in the 11%-15% group; 13% in the 15%-21% group and 15% in the >21% group (P=.3 for trend). However, the magnitude of absolute risk reduction increased with increasing risk. The researchers calculated that 5 years of BP-lowering therapy for 1,000 patients in each group would prevent 14, 20, 24 and 38 CV events, respectively (P=.04). The number needed to treat for 5 years to prevent one CV event was 71 in the lowest-risk group and 26 in the highest-risk group.

“This finding provides support for the notion that BP-lowering treatment should target those at greatest CV risk, not just those with the highest BP levels,” the researchers concluded. “A risk-based approach is likely to be more cost-effective than a BP-based approach, and could simultaneously reduce the numbers of patients needing treatment, and control drug costs, while increasing the numbers of averted strokes and heart attacks.”

In a related editorial, Paolo Verdecchia, from the department of medicine at the Hospital of Assisi, Italy, and Gianpaolo Reboldi, from the department of medicine at University of Perugia, Italy, acknowledged that these study results were expected, but timely and important. “Its findings could affect future revisions of hypertension guidelines that seem to be reluctant to consider total CV risk, instead of BP alone, as the main driving force to guide initiation of treatment,” they wrote.

Disclosure: See the full study for a list of the researchers’ relevant financial disclosures. Verdecchia and Reboldi report no relevant financial disclosures.

For more information:

Sundström J. Lancet. 2014;384:591-598.

Verdecchia P. Lancet. 2014;384:562-564.