Thursday, January 21, 2010

Hypertension, HEDIS, Excessive Blood Pressure Lowering, Polypharmacy and Implications for Care & Disease Management

Just what do the two numbers in a 'blood pressure' (for example, 120/80) really mean? What happens if the pressures are too high? Suppose just one number is high... how should it be addressed? How should the quality of care be measured among persons with an elevation in just one number? Can overzealous pursuit of high blood pressure lead to bad outcomes and, if so, how should that be measured in populations?

Thanks to a recent publication in the American Journal of Managed Care, your Disease Management Care Blog addresses the controversy.

The DMCB thinks of the two numbers as the highest and lowest measured pressures in the body's arteries that are generated by each heart beat. When the heart muscle contracts, the pressure increases until it peaks. Then the heart relaxes to fill with blood for the next pump. The blood pressure falls during this time until the heart begins to squeeze again. Therefore, think of 'blood pressure' as the peak increase and bottoming out of the pressure that is generated by each heart beat. Most of the time, a person's blood pressure is in between the top number (the systolic blood pressure) and the bottom number (the diastolic blood pressure). We're constantly bouncing between the two extremes.

It's been known that most people seem to have a peak or systolic blood pressure of 120 millimeters of mercury and a bottom or diastolic blood pressure of 80 millimeters of mecury. When those pressures increase, there is increased wear and tear on the inside walls of the arteries, leading to heart attack, strokes and kidney disease. Among persons without diabetes or kidney disease, decades of research have shown that a blood pressure of more than 140 systolic or 90 diastolic (the short hand being '140/90') results in significant enough damage to warrant treatment. If diabetes or kidney disease is present, the treatment threshold numbers are even lower at 130/80.

Which brings us to today's population-based care management conundrum: what should patients and treating health providers do with the category of high blood pressure where there is an elevation in only one of the two blood pressure measures? The reason that is important is because treating one high blood pressure number may cause the other to become dangerously low. For example, (when diet and exercise are not enough) pursuing a systolic blood pressure of 130 or higher with drugs in a person with diabetes could result in their normal diastolic blood pressure going below 70. According to this paper (the info is summarized on Figure 1), that can lead to an increased risk of heart attack and stroke.

This is not just a question for patients, providers or disease/care management organizations. It's also an important wrinkle in the national pursuit of health care quality. For example, a strict interpretation of the National Committee for Quality Assurance (NCQA) HEDIS® measures for successful blood pressure control suggests all persons with diabetes should have blood pressures less than 130 systolic and less than 80 diastolic - with no allowance for the unlucky patients with a 'successfully' treated systolic pressure that is less than 130, causing a concurrent diastolic blood pressure below 70.

Another criticism of the hypertension NCQA HEDIS® measure is that it doesn't recognize that sometimes blood pressure pills simply don't work. Most clinicians stop prescribing additional medications when the patient is on three. Once a patient reaches that point, additional pills are unlikely to work but are more likely to cause side effects.

This can be a problem, because 'all or nothing' blood pressure quality like less than 130 and less that 80 metrics - while well meaning, relatively simple to measure and based on the science - fail to capture the more subtle realities of of hypertension care that are also tied to outcomes (like excess heart attacks) and quality of life (medication side effects).

Which is why this paper published in the latest January 2010 American Journal of Managed Care is important. The authors looked at nine community-based general internal medicine clinics' patients 'of an unnamed academic healthcare system,' thanks to having access to an 11,000 person registry that captured the blood pressure (BP) readings of each and every patient. Two pools of patients were studied: 125 with diabetes who had a recent BP that did not meet the HEDIS criteria of less than 130/80 but were less than 140/90, and 125 patients with BPs or 140/90 or greater. In examining their electronic medical records, they found there were 31 (or 25%) patients in the first pool that were taking three blood pressure prescription medications and/or had a diastolic blood pressure less than 70; there were 43 (34%) patients in the second pool on three or more prescription medications and/or had the low diastolic blood pressure. Among those aged more than 65 years, the numbers were even higher: 58% in the first pool and 60% of those in cohort B took 3 or more antihypertensive medications and/or had the low diastolic pressure.

From a pure unrefined HEDIS® measurement standpoint, having a quarter to one thrid of patients with 'out of control' blood pressure would look bad. DMCB readers have long known there is more to the story. This AJMC study helps us understand the problem better.

The NCQA's Executive VP Greg Pawlson and Partners Healthcare's Thomas Lee would seem to agree. They penned an accompanying editorial in the same issue of AJMC that explains that when it comes to quality measures like those used by the NCQA, '100% performance is not the goal... that clinical judgement should be used' in applying the measure to populations and not be used to 'dictate the care of any individual patient.' They also suggest that the NCQA is open to modifying its measurement guidelines and look forward to the day when real time registries can provide more detailed measurement options.

Hear hear says the DMCB.

What does this mean for disease management organizations (DMOs)? Since DMOs also typically maintain high performance registries, they should already have access to the level of detail that can not only report the standard 'blunt' HEDIS® measures but also gauge the level of polypharmacy over-treatment or excessive BP lowering. Being able to educate your customers about these subtleties and report these data will be a competitive advantage, especially if the NCQA modifies its HEDIS® criteria.

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