Is HBP an inflammatory disease?

New link between inflammation and high blood pressure in women

By Emily Andrews

Is hypertension an inflammatory disease? Yes --well, at least in part, according to a new analysis from the Women's Health Study in the December 10 issue of the Journal of the American Medical Association (JAMA ).

The study has found a link between C-reactive protein (CRP), a type of protein in the blood that increases during episodes of acute inflammation, and future development of hypertension in women over 45 years old. But is the test still too general to be useful?

Elevated CRP is used as a general test for a variety of conditions, such as tuberculosis, lupus, rheumatism and cancer, making it difficult to pinpoint what disorder a patient might be suffering from. Until now its most important use was testing for atherosclerosis, or hardening of the arteries, an important factor in heart disease and stroke-- even though it remains unclear whether CRP is merely a marker or actually plays a role in causing atherosclerosis.

There has long been speculation that high blood pressure is in part an inflammatory disorder but the evidence was not really there to support it. The JAMA study set out to find whether or not there was a significant link using CRP levels as an indicator.

Researchers followed 20,525 US female health professionals over the age of 45 for eight years. They found that women with high CRP levels had twice the risk of developing hypertension as women with lower CRP levels.

The increased risk persisted after adjustment for body mass index, smoking, family history and other coronary risk factors, and was present in subjects with initial blood pressure lower than 100/65. Risk was not affected by use of hormone replacement therapy.

The findings, however, lead to more questions than answers. "Although the current data provide evidence for a critical role of inflammation in the development of hypertension, the mechanisms of this effect are uncertain," said the study's authors.

Because high CRP levels can be indicators for so many disorders, it is still too early to tell how the findings of the JAMA study could be applied in practice. The problem remains that since all kinds of inflammation -- from tuberculosis to back pain -- can make CRP levels go up, it's still too hard to use this as an accurate test for hypertension.

So what's a doctor to do? Dr Norm Campbell, the spokesman for the Heart and Stroke Foundation of Canada, suggested that while the findings are interesting for researchers looking into reasons why some people develop hypertension, doctors shouldn't rush to send their patients for CRP tests. Instead he advised they should focus on encouraging their patients to get checked routinely for hypertension from the time they hit middle age. So don't throw away that blood pressure gauge just yet.