Adherence to protease inhibitors, HIV-1 viral load, and development of drug resistance in an indigent population.
OBJECTIVE
To examine the relationship between adherence, viral suppression and antiretroviral resistance in HIV-infected homeless and marginally housed people on protease inhibitor (PI) therapy.


METHODS
A cross-sectional analysis of subjects in an observational prospective cohort systematically sampled from free meal lines, homeless shelters and low-income, single-room occupancy (SRO) hotels.


METHODS
Thirty-four HIV-infected people with a median of 12 months of PI therapy.


RESULTS
Adherence measured by periodic unannounced pill counts, electronic medication monitoring, and self-report; HIV RNA viral load; and HIV-1 genotypic changes associated with drug resistance.


RESULTS
Median adherence was 89, 73, and 67% by self-report, pill count, and electronic medication monitor, respectively. Thirty-eight per cent of the population had over 90% adherence by pill count. Depending on the measure, adherence explained 36-65% of the variation in concurrent HIV RNA levels. The three adherence measures were closely related. Of 20 genotyped patients who received a new reverse transcriptase inhibitor (RTI) when starting a PI, three had primary protease gene substitutions. Of 12 genotyped patients who received a PI without a new RTI, six had primary protease gene substitutions (P < 0.03).


CONCLUSIONS
A substantial proportion of homeless and marginally housed individuals had good adherence to PI therapy. A strong relationship was found between independent methods of measuring adherence and concurrent viral suppression. PI resistance was more closely related to the failure to change RTI when starting a PI than to the level of adherence.
Bangsberg
D R
DR
Epidemiology and Prevention Interventions Center, Division of Infectious Diseases, San Francisco General Hospital, University of California San Francisco, 94110, USA. db@epi-center.ucsf.edu
Hecht
F M
FM
Charlebois
E D
ED
Zolopa
A R
AR
Holodniy
M
M
Sheiner
L
L
Bamberger
J D
JD
Chesney
M A
MA
Moss
A
A
D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000627:therapeutic use; D015331:Cohort Studies; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004359:Drug Therapy, Combination; D005260:Female; D005838:Genotype; D017320:HIV Protease Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D015497:HIV-1 / Q000235:genetics / Q000302:isolation & purification; D006703:Ill-Housed Persons; D006801:Humans; D008297:Male; D008489:Medical Indigency; D015999:Multivariate Analysis; D010349:Patient Compliance; D018894:Reverse Transcriptase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use; D019562:Viral Load
D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D018894:Reverse Transcriptase Inhibitors