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Procedure
Practice 09/15/99 - Coding
Recommendations
Feature
Article 09/15/99:
HIV Infections
and AIDS
HIV infections, AIDS, and their myriad of complications are
diagnoses that many coders see every day in the course of
their jobs. The CDC reports that AIDS is the leading cause
of death among adults aged 25 to 44 in the United States.
This month, we review the basic epidemiology of HIV infection,
discuss disease progression and treatment, and review pertinent
coding guidelines.
Introduction
Acquired immunodeficiency syndrome (AIDS) is characterized
by the loss of a specific subset of T lymphocytes. Progressive
loss of these cells, known as CD4+ lymphocytes, leads to severe
immunosuppression, neurological complications, opportunistic
infections, and neoplasms that rarely occur in healthy people
with intact immune systems. Although the precise mechanisms
leading to the destruction of the immune system are not completely
understood, abundant epidemiologic, virologic, and immunologic
data support the conclusion that infection with the human
immunodeficiency virus (HIV) is the underlying cause of AIDS.
CDC Definition of AIDS
AIDS is the most advanced stage of HIV infection. The Centers
for Disease Control (CDC) in Atlanta, GA, is responsible for
tracking the spread of AIDS in the United States. For surveillance
purposes, the CDC currently defines AIDS in an adult or adolescent
age 13 years or older as the presence of one of 26 AIDS-indicator
conditions, such as Kaposi's sarcoma (KS), Pneumocystis carinii
pneumonia (PCP), or disseminated Mycobacterium avium complex
(MAC), in the setting of a CD4+ T lymphocyte count of less
than 200. In children younger than 13 years, the definition
of AIDS is similar to that in adolescents and adults, except
that lymphoid interstitial pneumonitis and recurrent bacterial
infections are included in the list of AIDS-defining conditions.
The CDC surveillance definitions are useful epidemiological
tools to quantify HIV-induced immunosuppression and its manifestations.
However, AIDS represents only the end stage of a continuous
progressive process, beginning with primary infection with
HIV, continuing with a chronic phase that is usually asymptomatic,
and leading to progressively severe symptoms and, ultimately,
profound immunodeficiency, opportunistic infections, and neoplasms.
Tracking the Epidemiology of AIDS
In 1981, clinical investigators in New York and California
observed among young, previously healthy, homosexual men an
unusual clustering of rare diseases, notably Kaposi's sarcoma
(KS) and opportunistic infections such as Pneumocystis carinii
pneumonia (PCP), as well as cases of unexplained, persistent
lymphadenopathy. Another rare opportunistic disease, disseminated
infection with the Mycobacterium avium complex (MAC), also
was seen frequently in these first AIDS patients. It became
clear that these men had a common immunologic deficit, an
impairment in cell-mediated immunity resulting from a profound
loss of "T-helper" cells that bear the CD4 marker.
The fact that homosexual men constituted the initial AIDS
population in the United States led early investigators to
surmise that a homosexual lifestyle was specifically related
to the disease. This hypothesis was dismissed when the syndrome
was observed in distinctly different groups in the United
States. Cases of AIDS were reported in male and female injection
drug users; in hemophiliacs and blood transfusion recipients;
among female sex partners of bisexual men, and among infants
born to mothers with AIDS or with a history of injection drug
use.
Many public health experts concluded that AIDS could be explained
only if it were caused by an infectious microorganism transmitted
in the manner of hepatitis B virus: that is by sexual contact,
exposure to blood or blood products, or transmission from
mother to newborn infant. Early suspects for the cause of
AIDS were cytomegalovirus because of its association with
immunosuppression, and Epstein-Barr virus, which has an affinity
for lymphocytes. However, AIDS was a new phenomenon, and these
viruses already had a worldwide distribution. Epidemiologists
could find no convincing evidence to assign these viruses
or other known agents a primary role in this new disease syndrome.
By 1983, several research groups had focused on retroviruses
for clues to the cause of AIDS. The first report providing
evidence for an association between a retrovirus and AIDS
was published in May 1983. A group of French researchers isolated
a previously unrecognized retrovirus that attacked and destroyed
CD4+ lymphocytes. This virus later became known as the lymphadenopathy-associated
virus (LAV).
In 1984, researchers at the National Institutes of Health
isolated HTLV-III, another retrovirus that destroyed CD4+
lymphocytes. The researchers found that 100 percent (34 of
34) of AIDS patients tested were positive for HTLV-III antibodies
in a study in which none of 14 controls had antibodies.
Researchers in San Francisco subsequently reported the isolation
of a retrovirus they named the AIDS-associated retrovirus
(ARV) from AIDS patients in different risk groups, as well
as from asymptomatic people from AIDS risk groups. Like HTLV-III
and LAV, ARV killed CD4+ T cells.
By 1985, analyses of the nucleotide sequences of HTLV-III,
LAV, and ARV demonstrated that the three viruses belonged
to the same retroviral family and were strikingly similar.
In 1986, the International Committee of Viral Taxonomy renamed
the viruses the human immunodeficiency virus (HIV).
As a retrovirus, HIV is an RNA virus that codes for the enzyme
reverse transcriptase which transcribes the viral RNA into
a DNA copy that ultimately integrates into the host cell.
Within the retrovirus family, HIV is classified as a lentivirus.
One feature that distinguishes lentiviruses from other retroviruses
is their remarkable genetic complexity. While most retroviruses
that are capable of replication contain only three genes,
HIV contains a total of nine genes. This sophisticated gene
structure is believed to be at least partly responsible for
the variety and complexity of HIV disease syndrome manifestations.
Theories of Immune System Destruction
Researchers are studying how HIV destroys or disables CD4+
T cells, and many scientists think that a number of mechanisms
may occur simultaneously in an HIV-infected individual. Findings
suggest that the cell destroying mechanisms at work in HIV
include the following:
- Direct cell killing: Infected CD4+ T cells may be killed
directly when a large number of viruses are produced and
bud off from the cell surface, disrupting the cell membrane,
or when viral proteins and nucleic acids collect inside
the cell and interfere with cellular machinery.
- Syncytia formation: Infected cells also may fuse with
nearby uninfected cells, forming balloon-like giant cells
called syncytia. In test-tube experiments, these giant cells
have been associated with the death of uninfected cells.
The presence of so-called syncytia-inducing variants of
HIV has been correlated with rapid disease progression in
HIV-infected individuals.
- Apoptosis: Apoptosis occurs to a greater extent in HIV-infected
individuals, both in the bloodstream and lymph nodes, than
in healthy people. Infected CD4+ T cells may be killed when
cellular regulation is distorted by HIV proteins, probably
leading to their suicide by a process known as programmed
cell death or apoptosis. Uninfected cells also may undergo
apoptosis. Investigators have shown in cell cultures that
the HIV envelope alone or bound to antibodies sends an inappropriate
signal to CD4+ T cells causing them to undergo apoptosis
even if not infected by HIV.
- Innocent bystanders: Uninfected cells may die in an innocent
bystander scenario: HIV particles may bind to the cell surface,
giving them the appearance of an infected cell and marking
them for destruction by killer T cells. Killer T cells also
may mistakenly destroy uninfected cells that have consumed
HIV particles and that display HIV fragments on their surfaces.
Alternatively, because HIV envelope proteins bear some resemblance
to certain molecules that may appear on CD4+ T cells, the
body's immune responses may mistakenly damage such cells
as well.
- Anergy: Researchers have shown in cell cultures that CD4+
T cells can be turned off by a signal from HIV that leaves
them unable to respond to further immune stimulation. This
inactivated state is known as anergy.
- Superantigens: Other investigators have proposed that
a molecule known as a superantigen, either made by HIV or
an unrelated agent, may activate massive quantities of CD4+
T cells. Because HIV replication and spread occur much more
efficiently in activated cells, these hyperactive cells
are highly susceptible to HIVinfection and subsequent cell
death.
- Damage to Precursor Cells: Studies suggest that HIV also
destroys immature immune system precursor cells as well
as the parts of the bone marrow and the thymus needed for
the development of such cells. These organs probably lose
the ability to regenerate, further compounding the suppression
of the immune system.
Transmission
HIV is spread most commonly by sexual contact with an infected
partner. The virus can enter the body through the lining of
the vagina, vulva, penis, rectum or mouth during sex. HIV
also is spread through contact with infected blood. Prior
to the screening of blood for evidence of HIV infection and
before the introduction in 1985 of heat-treating techniques
to destroy HIV in blood products, HIV was transmitted through
transfusions of contaminated blood or blood components. HIV
frequently is spread among injection drug users by the sharing
of needles or syringes contaminated with minute quantities
of infected blood. Transmission from patient to health-care
worker or vice-versa may occur from accidental sticks with
contaminated needles or other accidental body fluid exposure.
Almost all HIV-infected children acquire the virus from their
mothers before or during birth, a process called perinatal
transmission. In the United States, approximately 25 percent
of pregnant HIV-infected women not receiving therapy have
passed on the virus to their babies. Most perinatal transmissions,
causing an estimated 50 to 80 percent of infections in children,
probably occur late in pregnancy or during birth. Although
the precise mechanisms are unknown, scientists think HIV may
be transmitted when maternal blood enters the fetal circulation,
or by mucosal exposure to virus during labor and delivery.
The risk of perinatal transmission is significantly increased
if the mother has advanced HIV disease, increased levels of
the virus in her bloodstream, or fewer numbers of CD4+ T cells.
Other factors that may increase the risk of perinatal transmission
are maternal drug use, severe inflammation of fetal membranes,
or a prolonged period between membrane rupture and delivery.
HIV also may be transmitted from a nursing mother to her infant.
Recent studies suggest that breast-feeding introduces an additional
risk of HIV transmission of approximately 14 percent among
women with chronic HIV infection.
Diagnosis
Because early HIV infection often causes no symptoms, it
is primarily detected by testing blood for the presence of
antibodies to HIV. HIV antibodies generally do not reach detectable
levels until one to three months following infection and may
take as long as six months to be generated in quantities large
enough to show up in standard blood tests. HIV testing may
also be performed on saliva and urine samples, in addition
to blood samples.
Two different types of antibody tests, ELISA and Western
Blot, are used to diagnose HIV infection. If a person is highly
likely to be infected with HIV and yet both tests are negative,
a doctor may test for the presence of HIV itself in the blood.
The person also may be told to repeat antibody testing at
a later date when antibodies to HIV are more likely to have
developed.
Babies born to HIV-positive mothers may or may not be infected
with the virus, but all carry their mothers' antibodies to
HIV for several months. If these babies lack symptoms, a definitive
diagnosis of HIV infection using standard antibody tests cannot
be made until after 15 months of age. By then, babies are
unlikely to still carry their mothers' antibodies and will
have produced their own if they are infected.
Recently, investigators have demonstrated the utility of
highly accurate blood tests in diagnosing HIV infection in
children 6 months of age and younger. One laboratory technique
called polymerase chain reaction (PCR) can detect minute quantities
of the virus in an infant's blood. Another procedure allows
physicians to culture a sample of an infant's blood and test
it for the presence of HIV. Currently, PCR assays or HIV culture
techniques can identify at birth about one-third of infants
who are truly HIV-infected. With these techniques, approximately
90 percent of HIV-infected infants are identifiable by 2 months
of age, and 95 percent by 3 months of age.
Progression
The initial stage of HIV infection is associated with wide
dissemination of the virus throughout the body and an abrupt
decline of CD4+ T cells in peripheral circulation. An immune
response to the virus follows with a resultant decrease in
detectable viremia. A period of clinical latency then ensues,
during which CD4+ T cells continue to decrease until they
fall to a critical level. The median period of time between
infection with HIV and the onset of clinically apparent disease
is approximately 10 years in the United States and other western
countries.
HIV RNA becomes detectable in a patient's blood within weeks
of infection and precedes the appearance of HIV antigen and
HIV antibody. Over the following weeks, the level rises to
a peak and then tapers to a relatively stable level that is
now referred to as the "viral load set point." For
an individual, this level tends to change relatively slowly
over the following months and possibly years. The actual level
varies greatly from patient to patient, and its magnitude
predicts the risk of disease progression.
The course of HIV disease also varies from individual to
individual. A small number of people die within months following
primary infection, while 5 percent of HIV-infected individuals
show no disease progression even after 12 or more years. Factors
such as age or genetic differences among individuals, viral
load and virulence of the individual strain of virus, as well
as influences such as co-infection with other microbes may
determine the rate and severity of HIV disease progression.
Many people have no symptoms when they first become infected
with HIV. Some people, however, have a flu-like illness within
a month or two after exposure to the virus. They may have
fever, headache, malaise, and enlarged lymph nodes in the
neck and groin. These symptoms usually disappear within a
week to a month and are often mistaken for those of another
viral infection. People are very infectious during this period,
and HIV is present in large quantities in genital secretions.
Persistent or severe symptoms may not surface for a decade
or more after HIV first enters the body in adults, or within
two years in children born with HIV infection. During the
asymptomatic period, however, HIV is actively multiplying,
infecting, and killing cells of the immune system. HIV's effect
is seen most obviously in a decline in the blood levels of
CD4+ T cells (also called T4 cells) – the immune system's
key infection fighters. The virus initially disables or destroys
these cells without causing symptoms.
During the course of HIV infection, most people experience
a gradual decline in the number of CD4+ T cells, although
some individuals may have abrupt and dramatic drops in their
CD4+ T-cell counts. A person with CD4+ T cells above 200 may
experience some of the early symptoms of HIV disease. Others
may have no symptoms even though their CD4+ T-cell count is
below 200.
As the immune system deteriorates, a variety of complications
begins to surface. One of the first such symptoms experienced
by many people infected with HIV is enlarged lymph nodes for
a period that may exceed three months. Other symptoms often
experienced months to years before the onset of AIDS include
a lack of energy, weight loss, frequent fevers and sweats,
persistent or frequent yeast infections (oral or vaginal),
persistent skin rashes or flaky skin, pelvic inflammatory
disease that does not respond to treatment, or short-term
memory loss. Some individuals develop frequent and severe
herpes infections that cause mouth, genital or anal sores,
or shingles, a painful herpetic neuralgia. Children may have
delayed development or failure to thrive.
Most AIDS-defining conditions are opportunistic infections
that rarely cause harm in healthy individuals. In people with
AIDS, however, these infections are often severe and sometimes
fatal because the immune system is so ravaged by HIV that
the body cannot fight off certain bacteria, viruses, and other
microbes. Opportunistic infections cause a range of symptoms
including cough, dyspnea, seizures, confusion, memory loss,
vision impairment, severe and persistent diarrhea, fever,
severe headaches, cachexia, extreme fatigue, nausea, vomiting,
lack of coordination, coma, abdominal cramps, or dysphagia.
As AIDS further debilitates the immune system, patients become
more susceptible to a variety of infections including tuberculosis,
cytomegalovirus infections, candidiasis, histoplasmosis, toxoplasmosis,
coccidiosis, among others.
The most common HIV-associated illness is Pneumocystis carinii
pneumonia (PCP). Kaposi's sarcoma (KS) is another common manifestation.
Kaposi's is a vascular tumor and systemic malignancy that
was rare until HIV appeared. The disease presents as purple
and brown spots or nodules on the lower legs, and can progress
rapidly and affect many body sites, including the skin, soft
tissues, palate, lungs, and lymph nodes.
Although children with AIDS are susceptible to the same opportunistic
infections as adults with the disease, they also experience
severe forms of the bacterial infections to which children
are especially prone, such as conjunctivitis, otitis, and
tonsillitis. As children with HIV become sicker, they may
suffer from chronic diarrhea due to opportunistic pathogens.
A lung disease called lymphocytic interstitial pneumonitis
(LIP), rarely seen in adults, also occurs frequently in HIV-infected
children. This condition, like PCP, makes breathing progressively
more difficult and often results in hospitalization. Children
may also suffer from severe candidiasis, a yeast infection
that can cause unrelenting diaper rash and infections in the
mouth and throat.
The Food and Drug Administration has approved a number of
drugs for the treatment of HIV infection. The first group
of drugs used to treat HIV infection, called nucleoside analog
reverse transcriptase inhibitors (NRTIs), interrupt an early
stage of virus replication. Included in this class of drugs
are zidovudine (also known as AZT), zalcitabine (ddC), didanosine
(ddI), stavudine (D4T), lamivudine (3TC) and abacavir succinate.
These drugs may slow the spread of HIV in the body and delay
the onset of opportunistic infections. They do not prevent
transmission of HIV to other individuals. The second group
of drugs are non-nucleoside reverse transcriptase inhibitors
(NNRTIs) such as delavirdine, nevirapine, and efavirenz. They
are also available for use in combination with other antiretroviral
drugs. The third class of anti-HIV drugs, called protease
inhibitors, interrupts virus replication at a later step in
its life cycle. They include ritonavir, saquinivir, indinavir,
and nelfinavir. Because HIV can become resistant to each class
of drugs, combination treatment is necessary to effectively
suppress the virus.
However, none of the available drug regimens cure people
of HIV infection or AIDS, and they all have side effects that
can be severe. AZT may cause a depletion of red or white blood
cells, especially when taken in the later stages of the disease.
If the loss of blood cells is severe, treatment with AZT must
be stopped. DdI can cause an inflammation of the pancreas
and painful nerve damage. The most common side effects associated
with protease inhibitors include nausea, diarrhea, and other
gastrointestinal symptoms. In addition, protease inhibitors
can interact with other drugs resulting in serious side effects.
A number of drugs are available to help treat opportunistic
infections to which people with HIV are especially prone.
These drugs include foscarnet and ganciclovir, used to treat
cytomegalovirus eye infections, fluconazole to treat yeast
and other fungal infections, and TMP/SMX or pentamidine to
treat Pneumocystis carinii pneumonia (PCP).
In addition to antiretroviral therapy, adults with HIV whose
CD4+ T-cell counts drop below 200 are given treatment to prevent
the occurrence of PCP, which is one of the most common and
deadly opportunistic infections associated with HIV. Children
are given PCP preventive therapy when their CD4+ T-cell counts
drop to levels considered below normal for their age group.
Regardless of their CD4+ T-cell counts, HIV-infected children
and adults who have survived an episode of PCP are given drugs
for the rest of their lives to prevent a recurrence of the
pneumonia.
Four anti-HIV agents are currently approved for use in children.
In addition, two protease inhibitors are now approved for
children. Many other promising new antiretroviral regimens
are being assessed for use in children including various combinations
of nevirapine, d4T, lamivudine (3TC), and 1592U89.
HIV-infected individuals who develop Kaposi's sarcoma or
other cancers are treated per current chemotherapy and radiation
therapy protocols, or with injections of alpha interferon,
a genetically engineered protein.
Effective October 1, 1994, the ICD-9-CM code structure uses
the following three code categories to classify HIV:
042, Human Immunodeficiency Virus
(HIV) Disease
V08, Asymptomatic Human Immunodeficiency
Virus (HIV) Infection
795.71, Nonspecific Serologic Evidence
of Human Immunodeficiency (HIV)
Cases of patients with HIV-related illness are classified
to 042. Cases of asymptomatic patients who are HIV-infected
but have no HIV-associated illness are classified to V08.
Nonspecific or otherwise inconclusive (but NOT negative) HIV
serology test results are coded to 795.71.
The following coding recommendations summarize the official
Coding Clinic guidelines. Refer to the Coding Clinic, 4th
Quarter, 1994, pages 29-36, for the complete set of guidelines
and clinical examples.
- Only code confirmed cases of HIV infection. A positive
serology test is not required for confirmation. Physician
documentation of HIV infection or HIV-related illness is
considered confirmation.
- Cases of previously diagnosed HIV-related illness are
coded to 042.
- In sequencing HIV diagnoses, the coder is bound by the
UHDDS definition of discharge diagnosis: "The condition
established after study to be chiefly responsible for occasioning
the admission of the patient to the hospital for care."
| a. |
Cases of
HIV-related illness need at least two codes: 042
to identify the HIV, and the correct code for the
associated illness or condition, for example, 176.0,
Kaposi's sarcoma of the skin. |
| b. |
If the HIV
patient is admitted for an unrelated condition,
that condition is sequenced first with 042 as an
additional diagnosis.
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- The exception to the above rule is coding for HIV in Pregnancy,
Childbirth and Puerperium. If an obstetrical patient was
admitted for an HIV-related illness, assign 647.8x,
Other specified infectious and parasitic diseases in
the mother classifiable elsewhere, but complicating pregnancy,
childbirth, or the puerperium, followed by 042 and the
code for the HIV-related illness.
- Cases of patients who have tested positive for HIV but
have never had a documented HIV-related illness or infection
are assigned V08 as a secondary diagnosis code.
- Inconclusive HIV test results are assigned code 795.71.
It should be noted that test results must be equivocal,
not negative. Discussion with the attending physician in
cases of unclear documentation may be needed.
- Testing for HIV is coded V72.6, Laboratory
examination, if the patient was seen only for HIV testing
(counseling is not included in this code).
| a. |
Counseling
after negative test results is coded V65.44.
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| b. |
Counseling
after positive test results is coded V08 provided
the patient was asymptomatic, and 042 in cases of
an HIV-related illness.
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Practice
Makes Perfect!
Are you ready for some hands-on
practice?
Read the patient report(s) on
our procedure
practice page.
Assign the appropriate codes and then compare your answers
with our coding
recommendations.
Good luck!
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If you have comments or suggestions about our code selections
or about any topic on our Coding Edge® pages, please e-mail
us at codingedge@lagunamedsys.com.
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