High blood pressure (BP) or hypertension affects one in four American adults and is a serious condition that can damage the blood vessels and eventually lead to several other conditions, including stroke, heart disease, renal disease and vision problems.
Hypertension is a condition in which blood pressure is persistently elevated for a long period of time. BP is the measure of the pressure of the blood against the blood vessel walls. This is measured as the heart is in its working phase, which is the systolic reading (top number), and the pressure exerted while the heart is at rest is the diastolic reading (bottom number). Continual high BP puts undue stress on the heart, blood vessels and other body organs.
ICD-9-CM classifies hypertension by type: primary or secondary, and by nature: benign, malignant and unspecified.
Malignant and Benign Hypertension
Malignant hypertension is an accelerated, severe hypertensive disorder characterized by rapidly rising BP, usually in excess of 140 mm diastolic and may be accompanied by encephalopathy, nephropathy, retinopathy, heart failure and/or myocardial ischemia. This may lead to a hypertensive emergency, papilledema and progressive renal failure. Hypertension described as accelerated is classified to malignant hypertension. Even though accelerated hypertension does not have the papilledema associated with malignant hypertension, they are otherwise very similar and ICD-9-CM groups them together for purposes of classification.
Coders must be cautious and not code "uncontrolled" hypertension to the malignant hypertension code. Uncontrolled hypertension does not have a separate code in ICD-9-CM and is in fact, a non-essential modifier to the index entry of "Hypertension."
Benign hypertension is a mild to moderate elevation in BP of prolonged duration without target organ (i.e., kidney, retinal, coronary) damage.
Within ICD-9-CM there are five hypertension categories that identify type:
401 Essential hypertension
402 Hypertensive heart disease
403 Hypertensive renal disease
404 Hypertensive heart and renal disease
405 Secondary hypertension
Assigning Hypertensive Codes
The Hypertension Table found under the main term, Hypertension, in the Alphabetic Index of ICD-9-CM, contains a complete listing of all conditions due to or associated with hypertension and classifies them according to malignant, benign and unspecified.
The appropriate fourth digit is used with codes from categories 401-405 to indicate malignant (.0), benign (.1) or unspecified (.9) hypertension. The coder should never assume that hypertension is malignant or benign without physician documentation. The physician must use the term "malignant" along with "hypertension" to use the fourth digit of "0".The fourth digit "9" should be assigned when the benign or malignant hypertension is not documented.
As mentioned above, there are different types, causes and co-morbid conditions associated with hypertension. The most common is essential hypertension, which is coded to category 401 Essential hypertension. Essential hypertension, also known as primary hypertension, is an elevation of systolic and/or diastolic BP of unknown cause. The diagnosis of hypertension is made based on a series of BP readings rather than on an isolated reading. The upper limit of normal BP in adults is 140/90 mm; it is much lower for infants and children and varies according to age. As indicated above, "benign" must be stated by the physician along with hypertension to assign code 401.1, Essential hypertension, benign. Otherwise code 401.9 Essential hypertension, unspecified is assigned.
Many coders incorrectly assume that a hypertensive crisis is malignant hypertension. However, because the term "crisis" is a nonessential modifier, 401.9, Essential hypertension, unspecified should be assigned when hypertensive crisis is listed as a diagnosis.
Certain heart conditions such as cardiomegaly, cardiovascular disease, myocarditis and heart failure may be associated with hypertension. When this is the case a code from category 402 Hypertensive heart disease is assigned. Codes from this category are assigned only when a causal relationship is stated or implied. Category 402 includes a fifth digit of "1"that indicates whether heart failure is present. Use an additional code from category 428 to identify the type of heart failure in those patients with heart failure. More than one code from category 428 may be assigned if the patient has systolic or diastolic failure and congestive heart failure (CHF). The cause and effect relationship between heart failure or other heart conditions and hypertension should not be assumed. If the documentation states due to hypertension or hypertensive heart disease, then a causal relationship is established. When the documentation mentions both conditions but without a stated casual relationship, each is coded separately. Sequencing is determined by the circumstances of the admission and the supporting documentation. For example:
CHF due to hypertension: 402.91 and 428.0
CHF with hypertension: 428.0 and 401.9
Assign codes from category 403, Hypertensive renal disease, when conditions classified to categories 585-587 are present. Unlike hypertension with heart disease, ICD-9-CM presumes a cause-and-effect relationship between renal disease and hypertension as hypertensive renal disease. The cause and effect relationship does not need to be stated by the physician. Assign fifth digit "1" if the patient has renal failure documented by the physician. Assign fifth digit "0" if there is no documentation of renal failure. Note that this guideline involves chronic renal failure only. If acute renal failure and hypertension are present without documentation of co-existing chronic renal failure, the conditions are reported separately with codes from the 401 and 584 categories. For example:
Hypertension with chronic renal failure: 403.91
Acute renal failure with hypertension: 584.9 and 401.9
Assign codes from category 404, Hypertensive heart and renal disease, when both hypertensive renal disease and hypertensive heart disease are documented by the physician. The relationship between hypertension and heart disease must be stated, while the relationship between hypertension and renal disease is assumed. Fifth digits identify whether the patient has heart failure and/or chronic renal failure in addition to hypertensive heart and renal disease. Fifth digits are as follows: "0" without mention of heart failure or renal failure; "1" with heart failure; "2" with renal failure; "3" with heart failure and renal failure. Assign an additional code from category 428, to identify the type of heart failure. More than one code from category 428 may be assigned if the patient has systolic or diastolic failure and CHF.
Secondary hypertension accounts for about 5 percent of all patients suffering from hypertension. Codes from category 405, Hypertension, secondary, are used to identify hypertension that may be caused by or due to a number of reasons including estrogen use, renal disease, renal vascular hypertension, primary hyperaldosteronism and Cushing's syndrome, pheochromocytoma and coarctation of the aorta. When conditions causing hypertension are cured or brought under control, the secondary hypertension may be stabilized or may even completely disappear. When reporting secondary hypertension two codes are required: one to identify the underlying etiology and one from category 405 to identify the hypertension. Sequencing of the codes is determined by the reason for admission or encounter. A fifth digit of "1" is used to report renovascular causes of secondary hypertension. For example:
Hypertension due to lupus: 710.0 and 405.99
Hypertension due to renal stenosis: 440.1, 405.91
Hypertensive cerebrovascular disease is a leading cause of stroke. Hypertensive cerebrovascular disease is reported with two separate ICD-9-CM codes. There are no combination codes to identify these diseases. First, assign codes from categories 430-438, Cerebrovascular disease, followed by the appropriate hypertension code from hypertensive disease categories 401-405.
Transient hypertension, or elevated/high blood pressure, without a diagnosis of hypertension, should be assigned to code 796.2, Elevated blood pressure reading without diagnosis of hypertension. Because a diagnosis of hypertension is made based on a series of blood pressure readings rather than a single reading, the coder should never assume that elevated blood pressure implies hypertension. When in doubt, the physician should be asked if the patient does have a diagnosis of hypertension. Assign code 642.3x for transient hypertension of pregnancy.
If the medical record documentation indicates postoperative hypertension, query the physician to determine if the hypertension was actually related to or was a complication of a procedure. If the hypertension is related to or is a complication of the procedure, code 997.91, Complications affecting other specified body systems, hypertension, is assigned. An additional code is used to identify the type of hypertension. If the physician does not agree that the hypertension is related to the operative episode or if further information cannot be obtained, only a code from the 401-405 series is assigned.
Take the following quiz to test your knowledge of coding cerebrovascular diseases.
1. A patient is diagnosed with CHF due to diastolic dysfunction due to hypertension. Which of the following is the correct code assignment?
b. 402.91, 428.0
c. 401.9, 428.30, 428.0
d. 402.91, 428.30, 428.0
2. Transient hypertension occurring during the postoperative period is documented by the physician. Which of the following is the correct code assignment?
b. 997.91, 401.9
c. 997.91, 796.2
3. A patient presents with CHF due to hypertensive heart and renal disease with chronic renal failure and type I diabetic nephropathy. The patient responds to lasix therapy and is discharged. Which of the following is the correct code assignment?
a. 404.93, 4280, 250.01, 585
b. 402.91, 428.0, 250.41, 585
c. 404.93, 428.0, 250.41
d. 404.91, 585, 250.01
4. A patient presents to the hospital for treatment of CHF. The patient also has accelerated hypertensive nephropathy and chronic renal failure. Which of the following is the correct code assignment?
a. 428.0, 403.01
b. 404.03, 428.0
c. 428.0, 403.91
d. 404.93, 428.0
This month's column has been prepared by Cheryl D'Amato, RHIT, CCS, director of HIM, and Melinda Stegman, MBA, CCS, manager of clinical HIM services, HSS Inc. (www.hssweb.com), which specializes in the development and use of software and e-commerce solutions for managing coding, reimbursement, compliance and denial management in the health care marketplace.
Answers to CCS-PREP!: 1. d. Three codes are used to completely describe this scenario. Assign code 402.91, Hypertensive heart disease, unspecified, with heart failure; code 428.30, Diastolic heart failure, unspecified; and code 428.0, Congestive heart failure, unspecified. The two additional codes provide the specificity required to report that the heart failure was diastolic type and congestive; 2. d. Code 796.2, Transient hypertension is assigned because the physician did not document whether the transient hypertension was postoperative or not. In this instance, unless the physician is queried, the complication code cannot be used. Transient hypertension is considered elevated blood pressure; 3. c. Assign codes 404.93, 428.0 and 250.41. The combination code 404.93 for hypertension heart and renal disease is used because the hypertension was documented as the cause for heart disease. The fifth digit of 3 is assigned to indicate heart failure and renal failure. The type of heart failure is assigned, 428.0, as well as a code for the diabetic nephropathy, 250.41. A separate code for the chronic renal failure is not required; 4. a. Code 428.0, Congestive heart failure is assigned first because the patient presented and was treated for CHF. Code 403.01, Hypertensive renal disease, malignant, with renal failure is also assigned to identify the accelerated hypertension with nephropathy and chronic renal failure. Under ICD-9-CM, hypertension described as accelerated is classified with malignant hypertension. A code from category 404 Hypertensive heart and renal disease is not used because a cause and effect relationship between the CHF and hypertension is not documented.