Profiling advanced disease in an Asian clinical human immunodeficiency virus cohort: comparison of two definitions for acquired immunodeficiency syndrome.

Objective: To compare advanced human immunodeficiency virus disease defined immunologically and clinically by evaluating the characteristics of human immunodeficiency virus patients in Hong Kong.
Design: Retrospective observational study.
Setting: A human immunodeficiency virus cohort database established at a university and the major human immunodeficiency virus specialist services in Hong Kong.
Patients: Patients diagnosed with acquired immunodeficiency syndrome at the study centres between 1985 and 2006 were included.
Main Outcome Measures: Comparison of advanced human immunodeficiency virus disease defined (a) clinically as World Health Organization stage IV, and (b) immunologically as a CD4 count lower than 350/microL.
Results: Between 1985 and 2006, a total of 1317 patients, a majority of whom Chinese, were evaluated. Of these, 914 (69%) and 335 (25%) fulfilled the criteria for immunologically and clinically defined advanced disease, respectively. The mean age of the study population was 38 years and male-to-female ratio 4:1. There were two peaks in the frequency distribution of CD4 counts, one at a low count of less than 100/microL and the other between 200 and 400/microL. All except four with clinically defined advanced disease had CD4 counts lower than 350/microL on presentation. Of those with immunologically defined advanced disease, men having sex with men accounted for a lower proportion in the clinically advanced category, and Pneumocystis pneumonia was the commonest advanced disease at presentation.
Conclusions: Both clinical and immunological definitions provide a consistent means for assessing advanced disease, the implications of which are different. Such profiling has been made possible through the operation of a standardised cohort database, which is useful in (1) enhancing human immunodeficiency virus epidemiology studies, and (2) evaluating the performance of public health services.