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Current Trends Update: Impact of the Expanded AIDS Surveillance Case Definition for Adolescents and Adults on Case Reporting -- United States, 1993

During 1993, local, state, and territorial health departments reported 103,500 acquired immunodeficiency syndrome (AIDS) cases among persons aged greater than or equal to 13 years in the United States, an increase of 111% over the 49,016 reported in 1992 (Figure_1). This increase resulted from the expansion of the AIDS surveillance case definition in 1993 *; in comparison, the number of cases based on the preexisting case definition decreased slightly. This report summarizes characteristics of persons reported with AIDS in 1993, compares these findings with data from 1992, and describes the impact of the change in the AIDS surveillance definition on AIDS case reporting. **

Of cases in 1993, 55,432 (54%) were reported based on conditions added to the definition in 1993; and 48,068 (46%) were reported based on pre-1993 defined conditions -- a 2% decrease from the number of cases reported in 1992 (Figure_1). Of the 55,432 cases reported based on 1993-added conditions, 50,061 persons (91%) had severe human immunodeficiency virus (HIV)-related immunosuppression only; 3988 (7%), pulmonary tuberculosis (TB); 1251 (2%), recurrent pneumonia; and 151 ( less than 1%), invasive cervical cancer (19 persons were reported with more than one of these opportunistic illnesses).

The number of case reports was highest during the first quarter of 1993 (n=33,875, a 178% increase over the same period in 1992) and declined throughout the year: 18,957 cases were reported during the fourth quarter, a 67% increase over the same period in 1992. Comparing the same quarters of 1993, the median interval between date of diagnosis and date of report declined from 9 months to 4 months among persons reported with the newly added criteria but remained stable for persons reported using pre-1993 criteria. Of the cases reported in 1993, 56% had been diagnosed in earlier years, compared with 42% of cases reported in 1992.

In 1993, substantial increases in the number of reported AIDS cases occurred in all regions of the United States (Table_1, page 168). Of areas reporting more than 250 cases, the proportion of cases based on the 1993-added criteria ranged from 35% in North Carolina (n=1353) to 71% in Colorado (n=1323).

The increase in reported cases in 1993 was greater among females (151%) than among males (105%) (Table_1, page 168). Proportionate increases were greater among blacks and Hispanics than among whites. The largest increases in case reporting occurred among persons aged 13-19 years and 20-24 years; in these age groups, a greater proportion of cases were reported among women (35% and 29%, respectively) and were attributed to heterosexual transmission (22% and 18%, respectively).

Compared with homosexual/bisexual men, proportionate increases in case reporting were greater among heterosexual injecting-drug users (IDUs) and among persons reportedly infected through heterosexual contact (Table_1). The largest proportionate increase in AIDS case reporting occurred among persons with hemophilia, although the total number of these cases was smaller than for the other HIV-exposure categories.

Females, blacks, heterosexual IDUs, and persons with hemophilia were more likely than others to be reported with 1993-added conditions (Table_2). Most of these differences were attributable to reports of the three opportunistic illnesses added in 1993; of 5371 persons reported with a 1993-added opportunistic illness, 26% were women, 48% were heterosexual IDUs, and 63% were black. The number of Hispanics reported under the 1993-added criteria reflected reports from Puerto Rico: 38% of the 3173 reports from Puerto Rico were based on the 1993-added criteria, compared with 54% of the 15,145 cases among Hispanics from other areas.

The pediatric AIDS surveillance case definition was not changed in 1993. During 1993, 968 children aged less than 13 years were reported with AIDS, an increase of 24% compared with the 783 cases reported in 1992. Of those 968 children, 50% were female, and most were either black (55%) or Hispanic (27%) and were infected through perinatal HIV transmission (93%). New York, Puerto Rico, and Florida reported 489 (51%) of the pediatric AIDS cases. Reported by: Local, state, and territorial health depts. Div of HIV/AIDS, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The expansion of AIDS surveillance criteria in 1993 altered both the process of AIDS surveillance and the number of reported cases. The dramatic increase in the number of cases reported probably represents a one-time effect of the expanded reporting criteria that primarily results from reporting of persons who had newly added conditions diagnosed before 1993.

The increase in the number of cases reported in 1993 (111%) exceeded the projected increase (75%) (1,2), indicating the rapid and efficient implementation of the revised AIDS surveillance criteria by many local and state health departments. Because the initial impact of the expanded case definition is likely to wane, the number of AIDS cases reported in 1994 is expected to be less than the number reported in 1993.

During 1993, the number of reported cases meeting the pre-1993 AIDS surveillance definition decreased 2% from 1992. This reflects the rapid adoption of the CD4+ reporting criteria, which was used for 91% of AIDS case reports that were based on the 1993-added conditions. Therefore, the case count using pre-1993 criteria is not a precise measure of the number of cases that would have been reported if the definition had not been changed because the reporting of conditions meeting the pre-1993 criteria is affected by reporting using the CD4+ and other expanded criteria. For example, some cases reported under the expanded criteria may have had a concurrent or subsequent AIDS-defining condition in 1993 that was not reported; conversely, reporting of these pre-1993 conditions may have been enhanced by follow-up of cases initially reported with a newly added condition.

In addition to active surveillance in hospitals and outpatient clinics, local health departments have employed different methods and sources to implement the expanded reporting criteria; these include laboratory-initiated surveillance for HIV antibody and CD4+ measurements (in states that require such reporting) and for AIDS-defining opportunistic infections and information obtained from TB and cancer surveillance registries (3,4). Group-specific differences may exist in the incidence of 1993-added conditions and in access to and use of HIV testing and clinical-care services. For example, the large increase in AIDS reporting among persons with hemophilia may reflect high levels of HIV testing and immunologic monitoring in this population in which new HIV infections have been rare since 1985. Females, IDUs, and blacks were most likely to be reported with new AIDS-defining opportunistic illnesses. This difference largely reflects the population coinfected with Mycobacterium tuberculosis and HIV (5).

In 1993, the rate of increase in case reporting was greatest for women, racial/ethnic minorities, adolescents, IDUs, and persons infected through heterosexual contact. These trends in AIDS case reporting are similar to those observed in previous reporting years and suggest that changes in 1993 reflect, in part, underlying changes in the epidemic. Because race and ethnicity are not risk factors for HIV infection, an assessment of risk behaviors is necessary to properly target prevention efforts. The higher incidence of AIDS among non-Hispanic blacks and Hispanics than among non-Hispanic whites emphasizes the need for culturally sensitive and appropriate prevention messages. Although the pediatric case definition remained unchanged in 1993, the number of children reported with AIDS increased and paralleled the increase in AIDS among women.

The surveillance information available as a result of the expanded AIDS reporting criteria provides a representative and more complete estimate of the number and distribution of persons with severe HIV-related immunosuppression and three major HIV-related illnesses that are particularly important among groups in whom the growth of the AIDS epidemic has been greatest. In general, persons with 1993-added conditions had higher CD4+ counts than other persons with AIDS. The ability to conduct surveillance for persons in earlier stages of HIV infection should result in more prompt recognition of changes in the trends of HIV transmission and disease. The expanded reporting criteria also have made reporting more complete because persons with 1993-added conditions who had died would not have been reported if the AIDS surveillance definition had not been changed. The addition of the pulmonary TB reporting criteria has more than doubled the number of persons with AIDS reported with TB. Although the number of HIV-infected women reported with invasive cervical cancer is relatively small, the inclusion of this potentially preventable and life-threatening condition in AIDS surveillance efforts provides an opportunity to monitor gynecologic care for HIV-infected women. The expanded AIDS surveillance information should facilitate community efforts to plan, direct, and evaluate HIV-prevention and HIV-care programs.

References

  1. CDC. 1993 Revised classification system for HIV infection and expanded surveillance case definition for AIDS among adolescents and adults. MMWR 1992;41(no. RR-17).

  2. CDC. Impact of the expanded AIDS surveillance case definition on AIDS case reporting -- United States, first quarter, 1993. MMWR 1993;42:308-10.

  3. CDC. Assessment of laboratory reporting to supplement active AIDS surveillance -- Colorado. MMWR 1993;42:749-52.

  4. Trino R, McAnaney J, Fife D. Laboratory-based reporting of AIDS. J Acquir Immune Defic Syndr 1993;6:1057-61.

  5. Slutsker L, Castro KG, Ward JW, Dooley SW. Epidemiology of extrapulmonary tuberculosis among persons with AIDS in the United States. Clin Infect Dis 1993;16:513-8.

* On January 1, 1993, the AIDS surveillance case definition for adolescents and adults was expanded beyond the definition published in 1987 to include all human immunodeficiency virus-infected persons with severe immunosuppression (less than 200 CD4+ T-lymphocytes/uL or a CD4+ T-lymphocyte percentage of total lymphocytes of less than 14), pulmonary tuberculosis, recurrent pneumonia, or invasive cervical cancer (1). 

** Single copies of this report will be available free until March 11, 1995, from the CDC National AIDS Clearinghouse, P.O. Box 6003, Rockville, MD 20849-6003; telephone (800) 458-5231.

+------------------------------------------------------------------- ---+ | Erratum: Vol. 43, No. 9 | |             | | SOURCE:43(11);211 DATE:Mar 25 1994 | |             | | In the article "Update: Impact of the Expanded AIDS | | Surveillance Case Definition for Adolescents and Adults on Case | | Reporting -- United States, 1993" in Table_2 on page 169, for | | "Asian/Pacific Islander," the number in the 1993-Added column | | should be 393. For "Person with hemophilia," the number in the | | Pre-1993 column should be 288; in 1993-Added, 753; and in the Total | | column, 1041. The percentages are correct as published. | |             | +------------------------------------------------------------------- ---+
Figure_1

Figure_1
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Table_1
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TABLE 1. Characteristics of persons with reported AIDS cases and percentage increase in the number of
cases, by year of report --- United States, 1992--1993
=======================================================================================================
                            1993 Reported cases
                           ---------------------       1992         % Increase
Characteristic                No.           (%)   Reported cases   1992 to 1993
-------------------------------------------------------------------------------
Sex
  Male                       86,986       (84.0)      42,445           105
  Female                     16,514       (16.0)       6,571           151

Age group (yrs)
  13-19                         555       ( 0.5)         177           214
  20-24                       3,722       ( 3.6)       1,600           133
  25-29                      14,680       (14.2)       7,021           109
  30-39                      47,415       (45.8)      22,358           112
  40-49                      26,956       (26.0)      12,609           114
  50-59                       7,514       ( 7.3)       3,700           103
   >=60                       2,658       ( 2.6)       1,551            71

Race/Ethnicity *
  White, non-Hispanic        47,003       (45.4)      23,305           102
  Black, non-Hispanic        36,951       (35.7)      16,582           123
  Hispanic                   18,318       (17.7)       8,541           114
  Asian/Pacific Islander        741       ( 0.7)         332           123
  American Indian/
    Alaskan Native              320       ( 0.3)         114           181

HIV-exposure category
  Male homosexual/
    bisexual contact         48,266       (46.6)      25,864            87
  History of
    injecting-drug use
    Women and
      heterosexual men       28,687       (27.7)      12,163           136
    Male homosexual/
      bisexual contact        5,745       ( 5.6)       3,028            90
  Person with hemophilia      1,041       ( 1.0)         360           189
  Heterosexual contact +      9,288       ( 9.0)       4,045           130
  Transfusion recipients      1,219       ( 1.2)         710            72
  No risk reported            9,254       ( 8.9)       2,846           ---

Region &
  Northeast                  30,876       (29.8)      13,243           133
  Northcentral               10,755       (10.4)       5,656            90
  South                      34,264       (33.1)      16,588           107
  West                       24,372       (23.5)      11,914           105
  U. S. territories           3,233       ( 3.1)       1,615           100

Total                       103,500      (100.0)      49,016           111
------------------------------------------------------------------------------
* Excludes persons with unspecified race/ethnicity (167 in 1993, 142 in 1992).
+ Persons whose origin is or who had sex with a person whose origin is a country where
  heterosexual transmission was presumed to be the predominant mode of HIV transmission
  (i.e., formerly classified by the World Health Organization as Pattern II countries) are no longer
  automatically classified as having heterosexually acquired AIDS. These persons are now classified
  as "no risk reported".
& Northeast = New England and Middle Atlantic regions; Northcentral = East North Central and
  West North Central regions; South = South Atlantic, East South Central, and West South Central
  regions; West = Mountain and Pacific regions.
=======================================================================================================

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Table_2
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TABLE 2. Number and percentage of persons with AIDS meeting the 1993 surveillance
case definition criteria, by pre-1993 and 1993-added definitions -- United States
======================================================================================================
                              Pre-1993          1993-Added            Total
                             (n=48,068)         (n=55,432)         (n=103,500)
                          ----------------   ----------------   ----------------
Characteristic              No.      (%)       No.      (%)       No.       (%)
--------------------------------------------------------------------------------
Sex
  Male                    40,826    (84.9)   46,160    (83.3)   86,986    (84.1)
  Female                   7,242    (15.1)    9,272    (16.7)   16,514    (15.9)

Race/Ethnicity +
  White, non-Hispanic     21,878    (45.5)   25,126    (45.3)   47,003    (45.5)
  Black, non-Hispanic     16,630    (34.6)   20,321    (36.7)   36,951    (35.8)
  Hispanic                 8,958    (18.6)    9,360    (16.9)   18,318    (17.7)
  Asian/Pacific Islander     348    ( 0.7)      309    ( 0.7)      741    ( 0.7)
  American Indian/
    Alaskan Native           122    ( 0.3)      198    ( 0.4)      320    ( 0.3)

Risk exposure category
  Male homosexual/
    bisexual contact      23,355    (48.6)   24,911    (44.9)   48,266    (46.6)
  History of
    injecting-drug use    12,410    (25.8)   16,277    (29.4)   28,687    (27.7)
  Women and
    heterosexual men *     4,362    ( 9.1)    4,926    ( 8.9)    9,288    ( 9.0)
  Person with hemophilia     270    ( 0.6)      689    ( 1.2)      959    ( 1.0)

Region &
  Northeast               13,998    (29.1)   16,878    (30.4)   30,876    (29.8)
  Northcentral             4,969    (10.3)    5,786    (10.4)   10,755    (10.4)
  South                   16,688    (34.7)   17,576    (31.7)   34,264    (33.1)
  West                    10,402    (21.6)   13,970    (25.2)   24,372    (23.5)
  U. S. territories        2,011    ( 4.3)    1,222    ( 2.2)    3,233    ( 3.2)

Alive at report           31,657    (65.9)   48,960    (88.3)   80,617    (77.9)

No. with CD4+
  T-lymphocyte counts
  <200 cells/uL           28,563             51,130

Median                  44 cells/uL       121 cells/uL
--------------------------------------------------------------------------------
* Persons whose origin is or who had sex with a person whose origin is a country where
  heterosexual transmission was presumed to be the predominant mode of HIV transmission
  (i.e., formerly classified by the World Health Organization as Pattern II countries) are no longer
  automatically classified as having heterosexually acquired AIDS. These persons are now clas-
  sified as "no risk reported".
+ Excludes 167 persons with unspecified race/ethnicity.
& Northeast = New England and Middle Atlantic regions; Northcentral = East North Central and
  West North Central regions; South = South Atlantic, East South Central, and West South Central
  regions; West = Mountain and Pacific regions.
======================================================================================================

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