BARCELONA – A modest amount of blood pressure control over an average of 4 years produced a significant, long-term survival benefit in patients with type 2 diabetes, based on a 10-year follow-up of more than 8,000 patients.
"It is critically important to maintain active blood-pressure lowering in both the short and long term in order to derive the greatest possible reductions in mortality and major cardiovascular events" in patients with type 2 diabetes, Dr. John Chalmers said at the annual congress of the European Society of Cardiology.
Dr. John Chalmers
The results he reported showed that during 10 years of total follow-up, 4 years of concerted therapy with a dual antihypertensive-drug formulation on top of background therapy produced an average drop in blood pressure of 5.6/2.2 mm Hg, which was linked to a relative 9% decrease in mortality through the entire 10-year period.
Dr. Chalmers’ analysis used data from an average 6-year follow-up of patients after they completed a 4-year trial that had randomized them to treatment with either the combined formulation of the angiotensin-converting enzyme inhibitor perindopril and the diuretic indapamide, or to placebo. The 6-year assessment of these patients after they finished the closely regulated treatment phase while in the clinical trial is "the longest follow-up on the impact of blood pressure reduction in patients with diabetes," commented Dr. Lars Rydén, a cardiologist at the Karolinska Institute in Stockholm.
"The greatest part of the overall, cumulative benefit [over a 10-year period] was contributed by the carry forward of the in-trial benefits of active BP lowering," said Dr. Chalmers, senior director of the George Institute for Global Health in Sydney, Australia.
His study focused on data collected from patients enrolled in the ADVANCE (Action in Diabetes and Vascular Disease: Preterax and Diamicron-MR Controlled Evaluation) trial. This study randomized 11,140 patients with type 2 diabetes who were at least 55 years old and had at least one additional cardiovascular disease risk factor, to treatment with the combined formulation on top of their preexisting medications or to placebo plus existing medications (Lancet 2007;370:829-40). Patients in the placebo group were unable to receive an angiotensin-converting enzyme inhibitor during the study. The study was sponsored by Servier, the company that markets a combined perindopril and indapamide formulation (Preterax).
At enrollment, ADVANCE patients averaged 66 years old, had an average 8-year history of type 2 diabetes, and had an average blood pressure of 145/81 mm Hg. Three-quarters were on an antihypertensive regimen of some kind at entry into the study.
During the study’s 4 years of active treatment, patients randomized to receive the perindopril and indapamide combination had significantly reduced blood pressure, compared with the control patients. After 4 years, this linked to a 9% relative drop in the combined incidence of major macrovascular and microvascular events (including cardiovascular death, nonfatal stroke, and nonfatal myocardial infarction). Compared with the control group, this cut in events was statistically significant for the study’s primary endpoint. The antihypertensive intervention also was linked to a statistically significant, 14% relative drop in all-cause deaths.
To assess the longer-term impact of this 4-year intervention, Dr. Chalmers and his associates ran a post-trial observational study, ADVANCE-ON. Initially, 8,494 of the patients who completed ADVANCE (83% of surviving patients) agreed to participate in ADVANCE-ON; after another 6 years of follow-up, 5,131 patients remained under observation. During the extended 6 years of follow-up, patients from both the initial intervention arm and the initial control arm all maintained average blood pressures of roughly 137/75 mm Hg. The blood pressures of the original intervention and control patient arms "fully converged," Dr. Chalmers said.
During this 6-year period, patients received care from their personal physicians and could receive any antihypertensive regimen their physician prescribed. At their first follow-up medical examination after the end of the main ADVANCE study, about 40% of patients were on no antihypertensive drugs, 23% were on one drug, 21% were on two drugs, and the remainder were on higher numbers of antihypertensive drugs.
During the 6-year post-trial period, patients who had previously been in the active-treatment arm had a 6% relative reduction in all-cause mortality, compared with patients originally in the control arm, a difference that was not significant.
But when the researchers combined the 6-year post-trial follow-up with the in-trial results for a total median 10-year follow-up, they found an overall 9% relative cut in mortality in the intervention patients, compared with the controls, and a relative 12% drop in cardiovascular mortality.
The persistent, long-term benefits were "attenuated" compared with the shorter-term benefits seen during the active phase, but nonetheless they persisted and were consistent across all subgroups studied, Dr. Chalmers said.