Primary Care Coding Alert

An estimated 20 percent of patients have white-coat hypertension, so coders will likely be doing a lot of claims for ambulatory blood pressure monitoring (ABPM). But watch out: Medicare won't pay for ABPM unless the patient meets three criteria:

1. Office blood pressure greater than 140/90 mm Hg on at least three separate clinic/office visits with two separate measurements made at each visit

2. At least two documented blood pressure measurements taken outside the office that are less than 140/90 mm Hg

3. No evidence of end-organ damage.

White-coat hypertension patients have blood pressure readings that are higher in the office than at home, usually due to nervousness. There is no specific ICD-9 code for the disorder, but coders can use 796.2 (Elevated blood pressure reading without diagnosis of hypertension).

ABPM is becoming more popular. "The doctor attaches a portable blood pressure monitor, about the size of a Walkman radio, and a blood pressure cuff to the patient's arm," says Michael Ernst, PharmD, BCPS, co-director of the ABPM referral service in the Family Care Center of the University of Iowa Hospitals in Iowa City. The patient wears it home for 24 hours.

The monitor records the patient's blood pressure in intervals of 20 to 30 minutes, depending on how many readings the doctor wants. When the patient returns to the office, the information on the monitor is downloaded onto a computer and a report is generated.

"Based on the difference between the patient's blood pressure reading at home and in the office, the physician can determine whether he or she has hypertension or white-coat hypertension," Ernst says.