OSCAR: Olmesartan improves outcomes in patients with diabetes

Issue: May 2011

American College of Cardiology 60th Annual Scientific Sessions

NEW ORLEANS — Combination therapy with olmesartan and a calcium channel blocker was associated with similar rates of cardiovascular events and mortality when compared with a high-dose angiotensin II receptor blocker alone in patients with cardiovascular disease. However, dual therapy appeared inferior to angiotensin II receptor blocker monotherapy in patients with diabetes, according to results of the OSCAR study.

High-dose angiotensin II receptor blockers (ARBs) are more effective than low-dose ARBs for the prevention of CVD in patients with diabetic nephropathy or heart failure; however, the question of whether combination therapy with an ARB plus a calcium channel blocker (CCB) is superior to ARB monotherapy remains unanswered.

Hisao Ogawa, MD, PhD, professor in the department of CV medicine at Kumamoto University in Japan, and colleagues aimed to address this question by initiating the Olmesartan and Calcium Antagonists Randomized (OSCAR) study.

“The OSCAR Study is the first single trial in the world to examine the effect of high-dose ARB and ARB plus CCB in high-risk elderly patients,” Ogawa said during a press conference here.

Between June 2005 and May 2007, Ogawa and colleagues recruited 1,164 high-risk patients aged 65 to 84 years from 134 institutions in Japan. To qualify for inclusion, patients had to have uncontrolled blood pressure despite receiving treatment with the ARB olmesartan (Benicar, Daiichi Sankyo) and CVD or type 2 diabetes. The study’s primary endpoint was a composite of CV events, including cerebrovascular disease, coronary artery disease, HF, other atherosclerotic diseases, diabetic microvascular diseases and renal dysfunction, as well as all-cause mortality.

Patients were randomly assigned to receive daily high-dose olmesartan (40 mg) or a CCB plus olmesartan (20 mg). At 36 months, adequate blood pressure control was observed in both treatment groups. However, compared with monotherapy, combination therapy induced considerably greater decreases in BP, according to the researchers. Mean systolic BP was a mean 2.4 mm Hg lower and mean diastolic BP 1.7 mm Hg lower.

The researchers noted no significant differences between the two treatment arms in the number of primary endpoints. Fifty-eight events occurred in the monotherapy group vs. 48 in the combination group (HR=1.31; 95% CI, 0.89-1.92).

Results of a subgroup analysis, however, revealed a statistically significant difference between treatment groups in patients with pre-existing CVD. Patients assigned to combination therapy experienced considerably fewer CV events and death compared with those assigned monotherapy (24 vs. 51; HR=1.63; 95% CI, 1.06-2.52).

In addition, a second subgroup analysis indicated a higher rate of the primary outcome between treatment arms in patients with diabetes only, with 14 events occurring in the combination group and seven occurring in the ARB monotherapy group (HR=0.52, 95% CI, 0.21-1.28). The researchers also noted a significant treatment-by-subgroup interaction for the primary endpoints between patients with CVD and patients with diabetes only.

These results suggest that the relative effect of the two therapies is dependent on the presence of CVD or diabetes, according to the researchers. – by Melissa Foster

Disclosure: Dr. Ogawa received grant support during the last 5 years from Astellas, AstraZeneca, Bayer, Boehringer Ingelheim, Daiichi Sankyo, Eisai, Kowa, Kyowa Hakko Kirin, MSD, Novartis, Pfizer, Sanofi Aventis, Schering-Plough and Takeda.

For more information:

Ogawa H. LBCT IV 3015. Presented at: ACC 60th Annual Scientific Sessions; April 2-5, 2011; New Orleans.

It is interesting to see how different subgroups seem to benefit differently from different antihypertensive medicines. I think that people really do need to take into consideration the patient’s individual profile before deciding which drugs to use and which combination of antihypertensive treatments because many patients need more than one drug. That’s bottom line.

– Byron Lee, MD

Associate Professor of Medicine
University of California, San Francisco

Disclosure: Dr. Lee reports no relevant financial disclosures.

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