[Comparison of three methods to calculate adherence in patients receiving antiretroviral treatment].
BACKGROUND
Knowledge of the patient's adherence to antiretroviral treatment is extremely useful for monitoring HIV infection. Several methods have been proposed to calculate adherence, but they all have certain problems at application. The aim of this study was to compare three of the available methods for assessing medication adherence in order to determine their accuracy for this purpose.


METHODS
Three methods for evaluating medication adherence were prospectively studied: 1. Remaining pill count (RPC), 2. Structured interview (SI), and 3. Pharmacy registry of drug refills (DR). The RPC was considered the gold standard and sensitivity and specificity of the other methods was calculated according to the RPC. The study included 100 consecutive patients and had a follow-up of one year.


RESULTS
We were able to assess all three methods in 69 cases. The percentages of patients taking 95% or more of the prescribed dose according to the three methods were 72.5% (RPC), 85.5% (SI) and 81.2% (DR). Taking the RPC as gold standard, there was 75.1% concordance with the DR and 75.1% with the SI method. The sensitivities of the DM and SI were 52.6 % and 42.1 %, respectively. After one year of follow-up, patients with > 90% adherence (RPC) had a 1.29-times higher probability of achieving good virological response (CI 95% 1.04-1.62, p 5 0.0138).


CONCLUSIONS
Although concordance among the methods was acceptable, the SI and DR overestimated adherence as compared to the RPC. Since there is currently no ideal method for determining treatment adherence, it is important to combine several methods to minimize errors and provide results that are as close to the true situation as possible.
Codina
Carlos
C
Servicio de Farmacia. Hospital Clinic de Barcelona. Spain.
Martínez
Mireia
M
Tuset
Montserrat
M
del Cacho
Elena
E
Martín
María Teresa
MT
Miró
José M
JM
Mallolas
Josep
J
de Lazzari
Elisa
E
García
Felipe
F
Martínez
Esteban
E
Gatell
José M
JM
Ribas
Josep
J
D000328:Adult; D000368:Aged; D000465:Algorithms; D019380:Anti-HIV Agents / Q000627:therapeutic use*; D023241:Antiretroviral Therapy, Highly Active / Q000379:methods*; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*; D010352:Patient Dropouts / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D013030:Spain / Q000453:epidemiology; D016312:Treatment Refusal / Q000706:statistics & numerical data*
D019380:Anti-HIV Agents