Background HIV disease staging and classification systems are critical tools for tracking and
monitoring the HIV epidemic and for providing clinicians and patients with important
information about HIV disease stage and clinical management. Two major classification
systems currently are in use: the U.S. Centers for Disease Control and Prevention (CDC)
classification system and the World Health Organization (WHO) Clinical Staging and
Disease Classification System. The CDC disease staging system (last revised in 1993) assesses the severity of HIV
disease by CD4 cell counts and by the presence of specific HIV-related conditions. The
definition of AIDS includes all HIV-infected individuals with CD4 counts of <200
cells/µL (or CD4 percentage <14%) as well as those with certain HIV-related
conditions and symptoms. Although the fine points of the classification system rarely
are used in the routine clinical management of HIV-infected patients, a working
knowledge of the staging criteria (in particular the definition of AIDS) is useful in
patient care. In addition, the CDC system is used in clinical and epidemiologic
research. In contrast to the CDC system, the WHO Clinical Staging and Disease Classification System
(revised in 2005) can be used readily in resource-constrained settings without access to
CD4 cell count measurements or other diagnostic and laboratory testing methods. The WHO
system classifies HIV disease on the basis of clinical manifestations that can be
recognized and treated by clinicians in diverse settings, including resource-constrained
settings, and by clinicians with varying levels of HIV expertise and training. S: SubjectiveWhen a patient presents with a diagnosis of HIV infection, review the patient's
history to elicit and document any HIV-related illnesses or symptoms (see chapter
Initial History). O: ObjectivePerform a complete physical examination and appropriate laboratory studies (see
chapters Initial Physical Examination and Initial and Interim Laboratory and Other Tests). A: AssessmentConfirm HIV infection and perform staging. P: PlanEvaluate symptoms, history, physical examination
results, and laboratory results, and make a staging classification according to the
CDC or WHO criteria (see below). CDC Classification System for HIV Infection The CDC categorization of HIV/AIDS is based on the lowest documented CD4 cell count (Table 1) and on previously diagnosed HIV-related conditions (Tables 2 and 3). For example, if a patient had a condition that once met the criteria for Category B but now is asymptomatic, the patient would remain in Category B. Additionally, categorization is based on specific conditions, as indicated below. Patients in categories A3, B3, and C1-C3 are considered to have AIDS. |
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A
Asymptomatic, Acute HIV, or PGL | B
Symptomatic Conditions,#* not A or C | C
AIDS-Indicator Conditions* | | (1) ≥500 cells/µL | A1 | B1 | C1 | | (2) 200-499 cells/µL | A2 | B2 | C2 | | (3) <200 cells/µL | A3 | B3 | C3 |
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Category B symptomatic conditions are defined as symptomatic
conditions occurring in an HIV-infected adolescent or adult that meet at
least 1 of the following criteria: a) They are attributed to HIV infection or indicate a defect in
cell-mediated immunity. b) They are considered to have a clinical course or management that is
complicated by HIV infection. Examples include, but are not limited to, the following: - Bacillary angiomatosis
- Oropharyngeal candidiasis (thrush)
- Vulvovaginal candidiasis, persistent or resistant
- Pelvic inflammatory disease (PID)
- Cervical dysplasia (moderate or severe)/cervical carcinoma in situ
- Hairy leukoplakia, oral
- Idiopathic thrombocytopenic purpura
- Constitutional symptoms, such as fever (>38.5°C) or diarrhea
lasting >1 month
- Peripheral neuropathy
- Herpes zoster (shingles), involving ≥2 episodes or ≥1
dermatome
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- Bacterial pneumonia, recurrent (≥2 episodes in 12 months)
- Candidiasis of the bronchi, trachea, or lungs
- Candidiasis, esophageal
- Cervical carcinoma, invasive, confirmed by biopsy
- Coccidioidomycosis, disseminated or extrapulmonary
- Cryptococcosis, extrapulmonary
- Cryptosporidiosis, chronic intestinal (>1-month duration)
- Cytomegalovirus disease (other than liver, spleen, or nodes)
- Encephalopathy, HIV-related
- Herpes simplex: chronic ulcers (>1-month duration), or
bronchitis, pneumonitis, or esophagitis
- Histoplasmosis, disseminated or extrapulmonary
- Isosporiasis, chronic intestinal (>1-month duration)
- Kaposi sarcoma
- Lymphoma, Burkitt, immunoblastic, or primary central nervous system
- Mycobacterium avium complex (MAC) or M kansasii, disseminated or
extrapulmonary
- Mycobacterium tuberculosis, pulmonary or extrapulmonary
- Mycobacterium, other species or unidentified species, disseminated or
extrapulmonary
- Pneumocystis jiroveci (formerly carinii) pneumonia (PCP)
- Progressive multifocal leukoencephalopathy (PML)
- Salmonella septicemia, recurrent (nontyphoid)
- Toxoplasmosis of brain
- Wasting syndrome due to HIV (involuntary weight loss >10% of
baseline body weight) associated with either chronic diarrhea (≥2
loose stools per day ≥1 month) or chronic weakness and documented
fever ≥1 month
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WHO Clinical Staging of HIV/AIDS and Case DefinitionThe clinical staging and case definition of HIV for resource-constrained settings were developed by the WHO in 1990 and revised in 2005. Staging is based on clinical findings that guide the diagnosis, evaluation, and management of HIV/AIDS, and does not require a CD4 cell count. This staging system is used in many countries to determine eligibility for antiretroviral therapy. Clinical stages are categorized as 1 through 4, progressing from primary HIV infection to advanced HIV/AIDS (Table 4). These stages are defined by specific clinical conditions or symptoms. For the purpose of the WHO staging system, adolescents and adults are defined as individuals aged ≥15 years. |
| Primary HIV Infection | - Asymptomatic
- Acute retroviral syndrome
| | Clinical Stage 1 | - Asymptomatic
- Persistent generalized lymphadenopathy
| | Clinical Stage 2 | - Moderate unexplained weight loss (<10% of presumed or measured
body weight)
- Recurrent respiratory infections (respiratory tract infections, upper
respiratory infections, sinusitis, bronchitis, otitis media,
pharyngitis)
- Herpes zoster
- Minor mucocutaneous manifestations (angular cheilitis, recurrent oral
ulcerations, seborrheic dermatitis, prurigo, papular pruritic eruptions,
fungal fingernail infections)
| | Clinical Stage 3 | | Conditions for which a presumptive diagnosis can be made on the basis of clinical signs or simple investigations | - Severe weight loss (>10% of presumed or measured body weight)
- Unexplained chronic diarrhea for >1 month
- Unexplained persistent fever for >1 month (intermittent or
constant)
- Oral candidiasis (thrush)
- Oral hairy leukoplakia
- Pulmonary tuberculosis within the last 2 years
- Severe presumed bacterial infections (eg, pneumonia, empyema,
pyomyositis, bone or joint infection, meningitis, bacteremia)
- Acute necrotizing ulcerative stomatitis, gingivitis or
periodontitis
| | Conditions for which confirmatory diagnostic testing is necessary | - Unexplained anemia (hemoglobin <8 g/dL)
- Neutropenia (neutrophils <500 cells/µL)
- Thrombocytopenia (platelets <50,000 cells/µL)
| | Clinical Stage 4 | | Conditions for which a presumptive diagnosis can be made on the basis of clinical signs or simple investigations | - HIV wasting syndrome, as defined by the CDC (see Table 3, above)
- Pneumocystis jiroveci (formerly carinii) pneumonia
- Recurrent severe or radiologic bacterial pneumonia
- Chronic herpes simplex infection (oral or genital, or anorectal site)
for >1 month
- Esophageal candidiasis
- Extrapulmonary tuberculosis
- Kaposi sarcoma
- Central nervous system toxoplasmosis
- HIV encephalopathy
| | Conditions for which a confirmatory diagnostic testing is necessary | - Cryptococcosis, extrapulmonary
- Disseminated nontuberculosis Mycobacteria infection
- Progressive multifocal leukoencephalopathy
- Candida of the trachea, bronchi, or lungs
- Cryptosporidiosis
- Isosporiasis
- Visceral herpes simplex infection, cytomegalovirus infection
(retinitis or organ other than liver, spleen, or lymph node)
- Any disseminated mycosis (eg, histoplasmosis, coccidioidomycosis,
penicilliosis)
- Recurrent nontyphoidal Salmonella septicemia
- Lymphoma (cerebral or B-cell non-Hodgkin)
- Invasive cervical carcinoma
- Visceral leishmaniasis
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References |
