Human immunodeficiency virus acquired heterosexually abroad: expert panel assessment of the "indigenous/nonindigenous to the United Kingdom status" of cases

Background: In Scotland the proportion of human immunodeficiency virus (HIV)-diagnosed patients who were presumed to have acquired their infection abroad increased from 4% (12/269) in 1985 to 34% (53/154) in 2000. Several journalists and health professionals assumed that this increase in diagnosis rate reflected HIV among persons from Scotland who had acquired their infection while traveling abroad. Because of limitations in HIV surveillance data quality, no attempt had been made to distinguish diagnosed persons who were indigenous to the United Kingdom from those who were not. To address this problem, the investigators set out to interpret the existing surveillance data using a probability-based judgment approach.
Methods: A panel of travel medicine experts was employed to generate a judgment on reported heterosexual cases, presumed to have acquired HIV abroad and diagnosed before 2001, as to their likelihood of being indigenous to the United Kingdom (I) or not (NI). Median score thresholds were set to produce a range of possible values of I as a proportion of I + NI.
Results: For diagnoses made during 1991 to 1995, the possible value of I as a proportion of I + NI ranged between 17% (5/29) and 34% (23/68); for 1996 to 2000, the range was 32% (39/123) to 33% (43/130). Overall, 15% of cases were unclassifiable. Thus, up to one-third of HIV-diagnosed heterosexuals who likely acquired their HIV abroad originated in Scotland.
Conclusions: Amid current publicity about infections among immigrants, the distinction between I and NI group sizes should better inform public health professionals for resource allocation to prevent new HIV infection among indigenous persons, and for the health care of nonindigenous persons entering Scotland with HIV. Using classification criteria derived from this study, there are plans to publish such data routinely in the context of national surveillance.