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Internal Medicine Coding Alert

Reduce Pressure With a Hypertension Coding Checkup

Published on Fri Nov 01, 2002

Hypertension diagnosis coding can be a quagmire, but you can get your stress level and your denials down by making sure you pick the most specific code, back it up with documentation and meet new coding requirements for 2003 when heart disease is also involved.

Choosing the right ICD-9 code is critical for two reasons: to ensure that the patient isn't saddled with a wrong diagnosis that may affect future insurability, and to ensure that your office gets reimbursed for the proper CPT code reflecting the complexity of the visit.

"Coders should remember it's the ICD-9 code that establishes medical necessity when a claim is submitted," says Jean Acevedo, CPC, LHRM, senior consultant at Acevedo Consulting Inc., a national coding and compliance consulting firm in Delray Beach, Fla.

Begin your search for the right hypertension code (most are in the 401-405 series) by looking up hypertension in your ICD-9 book index, where you will find a chart detailing how to use the codes, says Sherry Straub, RHIT, CCS, CCS-P, coding and compliance manager at Esse Health, a multispecialty practice in St. Louis.

401 Requires Doctor Documentation

The toughest hypertension hurdle for coders is often the 401 series (Essential hypertension). This most commonly used series is for hypertension, or elevated blood pressure, without an apparent organic cause. ICD-9 requires a fourth digit to specify the type: malignant (401.0), benign (401.1) or unspecified (401.9).

Coders, however, cannot choose the fourth digit on their own, and physicians often find it difficult to pinpoint whether the hypertension should be labeled as "benign" or "malignant."

"I think there is a gray area between those two that makes it very hard to code," says Greg Pennock, MD, a cardiologist at the Heart Center of Southern Arizona in Tucson.

ICD-9 characterizes benign as "mildly elevated arterial blood pressure," whereas it describes malignant as "severe high arterial blood pressure; results in necrosis in kidney, retina, etc.; hemorrhages occur, and death commonly due to uremia or rupture of cerebral vessel."

Guidelines from the Joint National Committee on the Prevention, Evaluation and Treatment of High Blood Pressure and from the Merck Manual provide some clarification, indicating that hypertension should be coded as malignant (401.0) when it is life-threatening and that level of severity will most often be seen in the hospital, not the office, Straub says. The guidelines also indicate that benign (401.1) is the appropriate code in 90-95 percent of cases, Straub says.

To help physicians choose appropriately, Katherine Abel, CPC, vice president for operations at PriCare Inc., a medical practice management company in Franklin, Tenn., gives her physicians a list of hypertension codes along with definitions and instructions to indicate benign or malignant on the chart. If the doctor does not specify malignant or benign, the coder must choose unspecified (401.9) but some carriers will not cover the unspecified code, Abel says. Before using 401.9, you should try to get more information from the doctor to specify the type of hypertension, Abel says.

The physician may also use the unspecified code for a patient's initial workup for hypertension, but on subsequent visits should make a definitive diagnosis of either benign or malignant, Acevedo says.

For example, a patient presents with signs of hypertension, and the doctor codes 99214 (Office or other outpatient visit ...) with a diagnosis of 401.9. She tells the patient to get daily blood pressure checks and return in two weeks. All readings are elevated but none higher than 140/90. If the physician documents and bills 99214 with 401.9 again, the insurer may scrutinize this second visit or even downcode it based on the plan's internal billing edits due to the hypertension's continued unspecified nature, Acevedo warns.

"Billing on this second visit with an ICD-9 code of 401.1 is not only the accurate way to code the diagnosis butalso can help avoid the payer's scrutiny," Acevedo says.

Heart Disease Complicates Coding

The 402 series (Hypertensive heart disease) is anotherconfusing area for many coders because a patient can have heart disease and hypertension but not have hypertensive heart disease. The patient has hypertensive heart diseaseonly when the heart disease is caused by the hypertension.

"You can't use the 402 series unless the physician documents that cause-and-effect relationship," Straub says.

For example, you should use the 402 series, choosing again from benign, malignant and unspecified for the fourth digit, when the doctor notes in the chart that a hypertensive patient has been found, usually through an ECHO cardiogram, to have left ventricle heart damage resulting from hypertension, Pennock says. However, you should not use the 402 series if the doctor simply notes that a hypertensive patient has coronary artery disease.

2003 Code Changes Affect Heart Patients

Previously, a fifth digit was required with the 402 seriesto specify whether the patient had congestive heart failure. Effective with the 2003 ICD-9 changes, the fifth digit must be used differently to indicate whether the patient has heart failure, without mention of whether it is congestive. You must also use a secondary code one of 2003's new, more descriptive diagnosis codes in the 428 series (Heart failure) to document the specific type of heart failure.

Coders should communicate this change to their doctors, who may not be accustomed to specifying the type of heart failure associated with hypertension.

"Physicians need to be very careful to document this information," Straub says.

The 2003 change in coding for congestive heart failure also applies to the 404 series (Hypertensive heart and renal disease). You should use a fourth digit with this code to specify the type of hypertension and a fifth digit to indicate whether the patient has heart and/or renal failure. If the patient has heart failure, you must use a secondary diagnosis code from the 428 series to specify the type of heart failure.

When the patient has renal disease and hypertension without heart complications, use the 403 series (Hypertensive renal disease). Although ICD-9 does not presume that heart disease and hypertension are related, it does make this assumption about hypertension and renal disease unless the chart states otherwise, Straub says. Use the 403 series when the patient has any condition classifiable to categories 585 (Chronic renal failure), 586 (Renal failure, unspecified) or 587 (Renal sclerosis, unspecified), she says. Use fourth digits as above to specify the type of hypertension, along with a fifth digit to specify whether it is without mention of renal failure (0) or with renal failure (1).

You should use the 405 series (Secondary hypertension) for patients whose hypertension develops as a result of another problem, such as endocrine, vascular or kidney disease. Use a fourth digit to document the type of hypertension, and choose a fifth digit to indicate whether it is renovascular (1) or other (9). You should also use a second code to indicate the primary disease, such as 440.1 (Atherosclerosis of renal artery), that caused the hypertension.

Update Encounter Forms

One of the key reasons many offices don't code hypertension with enough specificity is that their encounter forms do not include all of the codes associated with hypertension, Acevedo says. With changes in coding for 402 and 404 in 2003, "This is a good time to review and update your superbill," Acevedo suggests.

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