Up-to-date information concerning HIV drug resistance
assay development and access, regulatory status, reimbursement and related
issues
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Resistance Test Availability and Regulatory Status
Tables and Info Pages
At-a-glance information about the availability and regulatory status of individual resistance tests and in-depth descriptions of assays, labs and lab test reports.
Genotypic Tests 
Point mutations may occur in the virus of patients who take antiretroviral agents. Many of these mutations have been linked to the phenotypic expression of drug resistance. Genotypic testing detects the presence of mutations in a patient's virus population by identifying codon changes that differ from the standard, or "wild-type," genetic sequence of HIV.
Phenotypic Tests 
Phenotypic tests provide information about the relative amount of antiretroviral drug required to suppress replication of the patient virus, compared to the amount of drug needed to supress replication of a laboratory strain of virus ("wild-type").
HIVresistanceWeb Test Information Articles:
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Genotype-Phenotype Discordances
From genotypic mixtures to atypical mutations, Robert W. Shafer, M.D., reviews the six most common causes of discordance between genotypic and phenotypic HIV drug resistance test results.
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Update From Barcelona on the Utility of Resistance Testing in Clinical Practice
Several new studies presented at the XIV International AIDS Conference in Barcelona addressed the utility and limitations of resistance testing in clinical practice. Here, Michelle E. Roland, M.D. takes a close look at the VIHRES and CERT studies, and at new findings of the Narval study.
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How Do the Experts Do in Interpreting Genotypes?
A critical component of HIV drug resistance testing is how well different genotype interpretation methods perform at predicting viral phenotypes and virologic responses to new drug regimens. Michelle E. Roland, M.D. examines new data on the congruity (or lack of it) between expert interpretations and on the concordance (again, or lack of it) of sequence interpretations by one academic and two commercial algorithms.
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Does Resistance Testing Effect Better Outcomes? A Review of Published Prospective Trials
Although six prospective studies of HIV drug resistance testing have now been published, their findings are far from harmonious. Hence, the question remains: "What is the clinical value of HIV drug resistance testing?" Michelle Roland, M.D. reviews the literature that keeps us guessing.
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Interpreting Genotypic Resistance Tests
"Imagine if the interpretation of a biopsy of a possible malignant tissue was different in different laboratories…" Robert W. Shafer, M.D. and Jonathan M. Schapiro, M.D. examine the interlaboratory discordance of genotypic HIV drug resistance test reports and review comparative approaches to identifying the best rules for genotypic interpretation.
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Two Important Resources for California Clinicians and Patients
Michelle E. Roland, M.D. provides an update on the California Department of Health Services’ Office of AIDS program to provide drug resistance testing to patients without private or public health insurance , and on the National HIV Telephone Consultation Service (Warmline) at 800-933-3413, which provides HIV resistance testing consultation and support for California clinicians.
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Update on FDA Regulation of HIV Drug Resistance Assays
Michelle E. Roland, M.D. returns to the important subject of how HIV drug resistance assays are regulated by the FDA. The current update examines a draft document prepared by FDA to help define regulatory requirements – such as which mutations must be analyzed, and “minimal interpretation algorithm” requirements -- for test manufacturers.
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Interlaboratory Variability in HIV Drug Resistance Testing
How accurate are your patients’ drug resistance test results? Bob Shafer, M.D. provides a thorough yet concise review of interlaboratory reproducibility and the technical and biologic limitations of HIV-1 sequencing.
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Clinical Information on Resistance Testing: New Clinical Trials and Improvements in Tests and Reports
Michelle Roland, MD, reports on clinical and technological issues in HIV drug resistance testing.
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HIV Drug Resistance Testing Policy,
Reimbursement and Education Updates: February 2000
Dr. Roland takes a look at the new DHHS Guidelines for the Use of Antiretroviral Agents in HIV-Infected Adults and Adolescents, which are the first U.S. national HIV treatment guidelines recommending the use of drug resistance testing in selected clinical situations. Dr. Roland also provides updates on Aetna's reimbursement policy for HIV drug resistance tests and on the National Association of AIDS Education and Training Centers (NAAETC)'s new HIV drug resistance testing education initiative.
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FDA Decides Company May Stop Enrolling Clinical Trial: Plans to Down-Regulate Resistance Tests Are Becoming Reality
Dr. Roland comments on the significance of Visible Genetics' decision to stop enrollment of its SEARCH study, a multi-center, controlled clinical trial of genotyping-assisted antiretroviral therapy, in light of the FDA's recent decision that clinical trial data will not be required for approval of genotypic resistance tests for certain well-defined mutations.
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FDA's CBER Defining Regulatory Requirements for Genotypic Resistance Tests
Dr. Roland reviews the proceedings of a Medical Device Panel hearing convened in September by the FDA's Center for Biologics Evaluation and Research (CBER) to examine ways to facilitate the development and approval of kit-based genotypic HIV drug resistance assays, while ensuring the quality and consistency of these devices and their use in clinical labs.
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FDA Considers the Uses of Resistance Evaluation in New Drug Development and Product Labeling
Dr. Roland digests the proceedings of a two-day workshop held by the FDA, as part of its recent Antiviral Drugs Advisory Committee meeting, to consider requirements for the use of genotypic and phenotypic resistance data in the development and approval of new antiretroviral drugs
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California State Office of AIDS ad hoc Advisory Committee Considers State Reimbursement Policy for Drug Resistance Assays
Dr. Roland reviews a recent Advisory Committee meeting convened by the California State Office of AIDS to "develop recommendations in the areas of reimbursement, education and research for HIV resistance testing policy and program development in California."
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Clinical Availability and Reimbursement Status of Antiretroviral Drug Resistance Assays
Dr. Michelle Roland provides the first in an ongoing series of articles concerning issues of access to and reimbursement for HIV drug resistance tests.
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