Donation deferral criteria for human immunodeficiency virus positivity among blood donors in northern Thailand

Abstract

Background: The purpose of this study was to develop human immunodeficiency virus (HIV) infection donation deferral criteria for blood donors in an HIV-epidemic area of northern Thailand, where the predominant means of transmission of HIV is through heterosexual contact.

Study design and methods: In a preliminary study, 2242 blood donors were interviewed, and their blood was tested for HIV antibodies between September 1993 and April 1994. The risk factors associated with HIV positivity were identified. Criteria to identify HIV-positive persons on the basis of a logistic equation were developed and applied to another group of 5769 prospective blood donors.

Results: A multivariate analysis showed the following odds ratios (OR) for traits that were independently associated with HIV positivity: younger age (OR = 0.93 for each additional year of age), male gender (OR = 2.41), having no more than a primary school education (OR = 2.00), being in the military (OR = 1.78), being unsure of one's own blood safety (OR = 2.00), history of injecting drug use (OR = 5.36), diagnosis of syphilis or positive syphilis serologic test in the past 12 months (OR = 2.67), and genital ulcer in the past 12 months (OR = 4.56). On the basis of the model, with a limit of <10 percent loss of uninfected donors, predicted probabilities of HIV positivity alone or of markers of infection with HIV, hepatitis B virus, or Treponema pallidum were calculated. With a cutoff of 6.5-percent estimated probability of HIV infection, derived from the logistic equation, the donor deferral criteria have 33.6-percent sensitivity and 8.3-percent positive predictive value for HIV positivity and 15.5-percent sensitivity and 18.4-percent positive predictive value for markers of infection with one of the three pathogens.

Conclusion: The proposed donor deferral system provides a more flexible, sensitive, and predictive tool for averting donation by those who, though HIV antibody-negative, are at a higher risk of being infected with HIV.

PIP: 2242 blood donors were interviewed and their blood tested for antibody to HIV between September 1993 and April 1994. The risk factors associated with being HIV seropositive were identified. Criteria to identify HIV-seropositive individuals on the basis of a logistic equation were then developed and applied to another group of 5769 prospective blood donors. Despite the availability of sensitive screening tests to detect HIV infection, blood donors can be infected but test seronegative if they have been infected for a period of six weeks or less. In Thailand, the rate of window-period blood donation at a university teaching hospital in Bangkok was reported to be relatively high compared with that in developed countries. The authors propose criteria capable of rooting out and excluding donations to the blood supply from people who are HIV seropositive, yet in the seronegative window period, in an HIV-epidemic area of northern Thailand, where the main mode of HIV transmission is through heterosexual contact. Younger age, being of male gender, having no more than a primary school education, being in the military, being unsure of one's own blood safety, having a history of IV drug use, diagnosis of syphilis or positive syphilis serologic test in the past 12 months, and genital ulcer in the past 12 months were each independently associated with being HIV seropositive. The proposed donor deferral system provides a more flexible, sensitive, and predictive tool for averting donation by those who, although HIV antibody-seronegative, are at comparatively greater risk of being infected with HIV.