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. 2006 Jun;26(3):140–146.

Fig. 1.

CDC classification for HIV stages.

The CDC Classification Scheme for HIV Disease
The CDC classification of HIV disease was first defined as a categorization of HIV-related symptoms into four groups and was explicitly for “ public health purposes” and not “ intended as a staging system” , although it was frequently treated as if it were a staging system in the AIDS literature. The current CDC classification system, from the revision in 1993, combines three categories of the CD4 count with three symptom categories and is closer to a staging system but is still not described as such. The CDC, however, proposed that it be used to “ guide clinical and therapeutic actions in the management of HIV-infected adolescents and adults” . This description of its intended use is close to the use of a staging system.
The definitions of the three CD4+ T-lymphocyte categories and the three categories of clinical conditions used in Table I follow:

  • Category 1: > 500 cells/mm3 (or CD4% > 28%);

  • Category 2: 200-499 cells/mm3 (or CD4% 14%-28%);

  • Category 3: < 200 cells/mm3 (or CD4% < 14%).

These categories correspond to CD4+ T-lymphocyte counts per microlitre of blood. The percentage of CD4+ T cells can be substituted for the count as indicated in parentheses. The lowest accurate, but not necessarily the most recent, CD4+ T-lymphocyte count or percentage should be used for classification purposes. The percentages were derived from correlating counts and percentages from 7 data sources. The correspondence of a 200 count to 14 percent showed little variation (range from the 7 data sources: 13 to 14%), but the correspondence of a 500 count to 29 percent was more variable (range from the 7 data sources: 22.5 to 39%).
Category A
Category A consists of one or more of the conditions listed below in an adolescent or adult (> 13 years) with documented HIV infection. Conditions listed in Categories B and C must not have occurred.

  • Asymptomatic HIV infection;

  • Persistent generalized lymphadenopathy;

  • Acute (primary) HIV infection with accompanying illness or history of acute HIV infection.

Category B
Category B consists of symptomatic conditions in an HIV-infected adolescent or adult that are not included among conditions listed in clinical Category C and that meet at least one of the following criteria: (a) the conditions are attributed to HIV infection or are indicative of a defect in cell-mediated immunity; or (b) the conditions are considered by physicians to have a clinical course or to require management that is complicated by HIV infection. Examples of conditions in clinical category B include but are not limited to:

  • Bacillary angiomatosis;

  • Candidiasis, oropharyngeal (thrush);

  • Candidiasis, vulvovaginal; persistent, frequent, or poorly responsive to therapy;

  • Cervical dysplasia (moderate or severe)/cervical carcinoma in situ;

  • Constitutional symptoms, such as fever (38.5 °C) or diarrhoea lasting > 1 month;

  • Hairy leukoplakia, oral;

  • Herpes zoster (shingles), involving at least two distinct episodes or more than one dermatome;

  • Idiopathic thrombocytopenic purpura;

  • Listeriosis;

  • Pelvic inflammatory disease, particularly if complicated by tubo-ovarian abscess;

  • Peripheral neuropathy.

For classification purposes, Category B conditions take precedence over those in Category A. For example, someone previously treated for oral or persistent vaginal candidiasis (and who has not developed a Category C disease) but who is now asymptomatic should be classified in Category B.
Category C
Category C includes the clinical conditions listed in the 1993 AIDS surveillance case definition (see subsequent section) For classification purposes, once a Category C condition has occurred, the person will remain in Category C.