A comparison study of multiple measures of adherence to HIV protease inhibitors.
BACKGROUND
Poor adherence to HIV protease inhibitors may compromise the effectiveness of treatment. Few studies have compared methods for measuring adherence or have related adherence measures to a clinical outcome.


OBJECTIVE
To examine the relationship among a composite score of adherence, the three primary measures of adherence, and HIV virologic response.


METHODS
Longitudinal cohort study.


METHODS
Public HIV clinic.


METHODS
108 HIV-infected adults receiving protease inhibitors or non-nucleoside reverse transcriptase inhibitors who were monitored for 666 monthly intervals.


METHODS
Medication Event Monitoring System (MEMS), pill count, and interview combined into a composite adherence score (CAS), and HIV viral load.


RESULTS
Mean antiretroviral adherence differed by adherence measure (MEMS, 0.63; pill count, 0.83; interview, 0.93; and CAS, 0.76). Composite adherence score decreased significantly over time. Composite adherence score, MEMS values, pill values, and interview values were statistically significantly associated with achievement of an undetectable viral load within 6 months of initiating therapy. Composite adherence score showed the strongest predictive relationship (odds ratios for a 10% increase in adherence for CAS, MEMS, pill count, and interview, respectively, were 1.26 [95% CI, 1.16 to 1.37], 1.13 [CI, 1.06 to 1.21], 1.10 [CI, 1.02 to 1.19], and 1.35 [CI, 0.94 to 1.94]).


CONCLUSIONS
Different measures applied to the same patient suggest different levels of adherence. Adherence may be underestimated by MEMS and overestimated by pill count and interview. A summary measure combining several measures is more strongly related to a clinical response, but more practical measurement methods are needed for clinical use.
Liu
H
H
Division of General Internal Medicine and Health Service Research, 911 Broxton Plaza, Room 102, Los Angeles, CA 90095-1736, USA. hhliu@ucla.edu
Golin
C E
CE
Miller
L G
LG
Hays
R D
RD
Beck
C K
CK
Sanandaji
S
S
Christian
J
J
Maldonado
T
T
Duran
D
D
Kaplan
A H
AH
Wenger
N S
NS
D000328:Adult; D000465:Algorithms; D004582:Electronics, Medical; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D006801:Humans; D007407:Interviews as Topic; D008137:Longitudinal Studies; D008297:Male; D010349:Patient Compliance; D012372:ROC Curve; D015203:Reproducibility of Results; D016896:Treatment Outcome; D019562:Viral Load
D017320:HIV Protease Inhibitors