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Availability of Flow Cytometric Immunophenotyping of Lymphocytes to Hospital Patients -- United States, 1990
The pathogenesis of disease caused by human immunodeficiency virus (HIV) is largely attributable to the decrease in T-lymphocytes bearing the CD4 cell-surface molecule (CD4+ T-lymphocytes) (1). The percentage of CD4+ T-lymphocytes among total lymphocytes and the percentages of other lymphocyte subpopulations (e.g., CD8+ T-lymphocytes) are generally measured by flow cytometric immunophenotyping (FCI) (also called immunophenotyping by flow cytometry (2), T-lymphocyte immunophenotyping (3), and fluorescence-activated cell sorting). FCI results are frequently used to guide the treatment of HIV-infected persons. To assess the availability of FCI to hospital patients, in 1990, the National Public Health and Hospital Institute (NPHHI), a private, nonprofit research institute, surveyed hospitals about their provision of FCI to patients. This report presents findings from the survey.
Since 1985, NPHHI has studied hospital care for HIV-infected patients by periodically surveying hospitals belonging to several national organizations (4).* A total of 1376 hospitals were surveyed regarding patient care provided in 1989, of which 822 (60%) responded. Of these respondents, 550 reported they had treated at least one patient for symptomatic HIV-related illness (HIV disease, including acquired immunodeficiency syndrome (AIDS)) during 1989. From these 550, 100 were randomly selected for the FCI survey. Telephone interviews were conducted with either the laboratory director or technical staff familiar with the hospital's use of FCI during 1990.
Of the 94 responding hospitals, 65 (69%) were private, 22 (23%) were nonfederal public, and seven (7%) were Veterans Affairs hospitals. Thirty-one (33%) were located in the Midwest, 26 (28%) in the South, 21 (22%) in the Northeast, and 16 (17%) in the West. The median number of hospital beds was 376, and a median of 17 (range: 1-1026) inpatients were treated for HIV disease in 1989. Nineteen (20%) of the 94 responding hospitals treated 4721 (80%) of the 5926 inpatients with HIV-related disease admitted to these hospitals.
Of the responding hospitals, 33 (35%) had performed FCI in their own laboratories; 57 (61%) had obtained FCI through outside laboratories. Three did not have requests for FCI, and one reported that FCI service was not available; each of these four treated three or fewer patients with HIV disease. Of the 33 hospitals that performed FCI in their own laboratories in 1990, 32 reported when they began FCI: five (16%) began during 1980-1983; 10 (31%), 1984-1987; and 17 (53%), 1988-1990.
The proportion of responding hospitals that performed FCI in their own laboratories in 1990 increased with the number of patients admitted to these hospitals for treatment of HIV disease in 1989. Of the eight hospitals that treated only one patient with HIV-disease, none performed FCI in their own laboratories. FCI was performed in-house at 12 (23%) of the 52 hospitals that reported treating two to 29 HIV-disease patients, 14 (54%) of the 26 hospitals with 30 to 199 HIV-disease patients, and seven (88%) of the eight hospitals with 200 or more HIV-disease patients. The 33 hospitals that performed FCI in-house treated 3794 (64%) of the 5926 total HIV-related disease inpatients in these hospitals.
Of the 57 hospitals that obtained FCI through outside laboratories, 41 (72%) used independent commercial laboratories, nine (16%) used laboratories at other hospitals, and seven (12%) used other (e.g., research, blood bank, or public health) laboratories.
The cost of FCI to the hospital and the amount charged to the patient varied with the number of component tests included in the FCI panel (including tests for cell-surface markers other than CD4 and CD8). Among the 47 hospitals that provided cost data, the median cost for FCI was $110 (range: $20-$297). Among the 39 that provided charge data, the median charge was $134 (range: $46-$570).
Reported by: AW Spolarich, MPA; DP Andrulis, PhD; VB Weslowski, MPA; National Public Health and Hospital Institute, Washington, DC. Div of HIV/AIDS, National Center for Infectious Diseases; Div of Laboratory Systems, Public Health Practice Program Office, CDC.
Editorial Note: Enumeration of CD4+ T-lymphocytes by FCI is used in routine management of HIV-infected persons to monitor the severity of immunodeficiency caused by HIV and as a basis for decisions regarding antiretroviral therapy and prophylaxis for Pneumocystis carinii pneumonia (5-7). In addition, the Social Security Administration uses the CD4+ T-lymphocyte count as part of the criteria for determining disability in persons with HIV-related illness (8). A proposed revision of the CDC classification system for HIV infection in adults and adolescents would classify HIV infection on the basis of the CD4+ T-lymphocyte count (or alternatively the percentage of CD4+ T-lymphocytes among total lymphocytes) as well as on clinical conditions (9).
This survey indicates that FCI is widely available to hospitals providing care to HIV-infected patients, either through the hospital's own laboratory or an outside laboratory. Although most hospitals provided FCI through an outside laboratory, the proportion performing FCI in their own laboratory has been steadily increasing. This proportion has been greater among hospitals treating more patients with HIV disease, suggesting it will continue to increase as the number of patients with HIV disease increases. Although this survey did not examine the availability of FCI to outpatient facilities, the finding that FCI is widely available to hospitals suggests that FCI may also be available to other types of health-care facilities.
The NPHHI survey supplements surveys conducted by CDC. In a 1989 survey of 279 laboratories that reported performing FCI, most (90%) tested fewer than 200 samples weekly, suggesting that their equipment was not fully utilized and could test more samples (3). Of these laboratories, 60% were located in hospitals; 83% reported testing specimens collected from other hospitals, private physicians, or clinics. In 1991, a survey of 264 laboratories yielded similar results (10).
In the NPHHI survey, costs and charges for FCI varied widely among hospitals. Lower amounts in some hospitals reflected the use of abbreviated FCI panels. Full panels include reagents that identify all the lymphocytes (i.e., T-, B-, and NK-cells), distinguish between T-lymphocytes that are CD4+ or CD8+, and provide internal quality-control checks. CDC recommends full panels because they are necessary for maximum quality control and avoidance of errors (2). Technologies being developed may help reduce both the cost and the requirement for specially trained personnel for this essential test service.
The widespread and increasing availability of FCI shown in the NPHHI survey reflects the increasing role of CD4+ T-lymphocyte monitoring in care of HIV-infected patients, which is important for timely therapy to delay the onset of AIDS and thereby improve the quality of life for these patients.
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