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Low targets in Primary Prevention?

The Journal of the American Medical Association has published the results of a study that compared the attainment of aggressive targets with standard targets in patients with type 2 diabetes.

The study recruited 499 American Indian men and women aged 40 years or older with type 2 diabetes and no prior CVD events. The trial was randomised but open label with a follow up of 3 years. Patients were assigned to aggressive targets of 110mmHg systolic blood pressure (SBP) and low-density lipoprotein cholesterol (LDL-C) of 1.8mmol/L or standard targets of 130mmHg SBP and 2.6mmol/L LDL-C. The primary outcome was progression of atherosclerosis measured by common carotid artery intimal medial thickness (C-IMT).

During the last 12 months of follow up mean SBP was 117mmHg (95% CI 115-118) in the aggressive group and 129mmHg (95% CI 128-130) in the standard group. Mean LDL-C was 1.86mmol/L (95% CI 1.78-1.94) and 2.69mmol/L (95% CI 2.61-2.74) respectively. The primary outcome was statistically significant (p<0.001); IMT regressed in the aggressive group and progressed in the standard group. Rates of adverse events related to blood pressure medication occurred more often in the aggressive group and this was statistically significant.

The study was not designed to assess differences in rates of cardiovascular events however the data were collected and analysed and were not different between the two groups. (1.6/100 and 1.5/100 person-years; P = 0.87) The authors conclude that, "further follow-up is needed to determine whether these improvements will result in lower long-term CVD event rates".

It should be noted that the patients recruited to this study are not representative of a broader UK population and that the standard target used in this study was more aggressive than current treatment targets in the UK. Despite these limitations this study again raises questions about the appropriateness of treating individual risk factors to low targets.

Action: Clinicians should continue to follow current targets as defined by the Department of Health and the National Institute of Health and Clinical Excellence. Blood pressure targets are currently 140/85mmHg or 140/80mmHg in patients with diabetes and total cholesterol should be treated to 5mmol/L or a 30% reduction from baseline, whichever is greater.