ACC: Intensive BP lowering does not reduce CV events in adult diabetics
The comprehensive ACCORD (Action to Control Cardiovascular Risk in Diabetes) trial embraced more than 10,251 adult participants between the ages of 40 and 79, who had type 2 diabetes for an average of 10 years and were at especially high risk of cardiovascular events, such as heart attacks, stroke or cardiac death. In this blood pressure arm of the larger ACCORD trial, the researchers enrolled 4,733 participants.
The results of the ACCORD blood pressure trial appear online today in the New England Journal of Medicine, along with the separate arm of the ACCORD lipid lowering trial. Results of the ACCORD blood sugar clinical trial were reported in 2008.
All participants were enrolled in the ACCORD blood sugar treatment clinical trial and maintained good control of blood sugar levels during the study, according to the researchers. In addition, participants were enrolled in either the blood pressure trial or the lipid trial and were treated and followed for an average of about five years.
According to the researchers, the ACCORD blood pressure trial is the largest clinical trial to test the effect on cardiovascular disease of systolic blood pressure below 120 mmHg, which is considered normal. Current blood pressure guidelines recommend that adults with type 2 diabetes maintain systolic blood pressure at less than 130 mm Hg.
According to the lead author William C. Cushman, MD, chief of preventive medicine at the Veterans Affairs Medical Center in Memphis, Tenn., previous clinical trials have only proven benefits to less than 140 mm Hg; however, observational studies have linked systolic blood pressure levels of 120 mmHg or below to lower cardiovascular disease rates in adults with type 2 diabetes. Therefore, the researchers decided a clinical trial was needed to determine the effects of treatment to reach this normal systolic blood pressure level in these patients.
Researchers randomly assigned 4,733 participants with elevated blood pressure to a target systolic blood pressure of either less than 120 mmHg (the intensive group) or to less than 140 mmHg (the standard group). A variety of FDA-approved blood pressure medications was used to reach blood pressure goals.
After an average follow-up of about five years, researchers found no significant differences between the intensive group and the standard group in rates of a combined endpoint including nonfatal heart attack, nonfatal stroke or cardiovascular death.
There were 208 cardiovascular events in the intensive group and 237 events in the standard group, Cushman reported.
The findings have surprised the cardiology community. Even the study’s discussant Eliot Saunders, MD, from the University of Maryland School of Medicine in Baltimore, suggested that popular ideology indicates the “lower the blood pressure, the better the outcomes. Therefore, physicians have been seeking to get blood pressure numbers lower.”
Despite the commonly held belief that achieving blood pressure of 120mmHg for patients achieves lower cardiovascular disease in type 2 diabetes through the observational studies, “until we had that data, we couldn’t recommend it,” Saunders said. “Today’s results indicate that we still cannot recommend a goal of 120mmHg as a way of mitigating risk.”
However, Saunders added there is “no question that the lower the blood pressure, the lower the risk in other patient groups, such as hypertension patients as they age, in certain ethnic populations.”
One positive finding from the ACCORD blood pressure trial was that lowering blood pressure to below the standard level significantly cut the risk of stroke by about 40 percent. The intensive blood pressure group had 36 strokes, compared to 62 strokes in the standard group.
Cushman cautioned, however, that participants in the intensive blood pressure group were more likely to have complications such as abnormally low blood pressure or high levels of blood potassium. The researchers reported that 77 events in the intensive groups compared to 30 in the standard group. In addition, some lab measures of kidney function were worse in the intensive therapy group, but there was no difference in the rates of kidney failure.
“Our results provide no conclusive evidence that targeting a normal systolic blood pressure compared with targeting a systolic blood pressure of less than 140 mmHg lowers the overall risk of major cardiovascular events in high risk adults with type 2 diabetes," said Cushman. "However, the study suggests that lower blood pressure levels in patients like those in ACCORD may reduce the risk of stroke. This finding is consistent with other blood pressure trials.”
"Our results also showed a higher risk of serious adverse events with more intensive blood pressure control," Cushman added. "Diabetic patients should discuss their systolic blood pressure goal with their health care provider and, as with any treatment, weigh the risks and benefits of various treatments to lower blood pressure."
Saunders noted that the patient population in the ACCORD blood pressure trial should be further examined for differences that led to this “non-positive result.”
The researchers cautioned that the results from ACCORD might not apply to patients who are at lower risk of cardiovascular disease than the ACCORD participants or to patients with more recently diagnosed type 2 diabetes.
The National Institutes of Health supported the comprehensive ACCORD trial.