ANTIRETROVIRAL DRUG-RESISTANCE TESTING IN ADULTS WITH HIV-INFECTION -IMPLICATIONS FOR CLINICAL MANAGEMENT

Objectives.-To review current knowledge of the biology and clinical im plications of human immunodeficiency virus (HIV) resistance to antiret roviral drugs, describe assays for measuring resistance, and assess th eir use in clinical practice. Participants.-The international AIDS Soc iety-USA assembled a panel of 13 physicians with expertise in basic sc ience, clinical research, and patient care relevant to HIV resistance to antiretroviral drugs. Evidence.-We reviewed available data from pub lished reports and presented at national and international research co nferences. Basic science research, clinical trial results, and expert opinions were used to form the basis of this report, Data on methods f or and characteristics of specific genotypic and phenotypic assays wer e obtained from manufacturers and service providers. Consensus Process .-The panel met regularly between October 1997 and April 1998, Panel s ubgroups developed and discussed different sections of the report befo re discussing them with the entire panel. Conclusions and suggested ap proaches to the use of resistance testing were determined by group con sensus. Conclusions.-Plasma HIV RNA level and CD4(+) cell count are th e primary values that should be used to guide the initiation of antire troviral therapy and subsequent changes in therapy. Possible causes of treatment failure other than development of drug resistance that shou ld be considered are adherence, drug potency, and pharmacokinetic issu es, Genotypic and phenotypic testing for HIV resistance to antiretrovi ral drugs may prove useful for individual patient management. Assays u nder development need validation, standardization, and a clearer defin ition of their clinical roles, Possible current roles of resistance te sting for choosing an initial regimen or changing antiretroviral thera py, as well as possible implications of the presence or absence of phe notypic resistance and genotypic changes, are discussed.