Validity of a stage of change instrument in assessing medication adherence in indigent patients with HIV infection.
BACKGROUND
Adherence to antiretroviral therapy (ART) is vital to achieve durable suppression of viral replication. Effective mechanisms to predict adherence can be difficult to implement in clinical practice settings. Self-administered questionnaires are a practical option for assessing patient adherence but may lack validation with objective measures of adherence.


OBJECTIVE
To examine the ability of a 2 item stage of change (SOC) questionnaire to predict medication adherence in indigent patients receiving ART.


METHODS
Patients participating in an ongoing study to examine adherence interventions were administered a 2 item SOC instrument to assess readiness for adherence behavior. The SOC instrument was given to patients prior to beginning ART and readministered after they had received 16 weeks of treatment. Electronic monitoring was used to examine the validity of the SOC instrument to predict patient readiness for adherence behavior.


RESULTS
Thirty-one patients completed the SOC questionnaire prior to beginning a new ART regimen. Most (87%) patients were male, had previously received antiretroviral therapy (77%), and had an AIDS diagnosis (77%). The SOC category determined at baseline was a poor predictor of adherence at 4 and 16 weeks; however, the SOC category determined after treatment onset (week 16) was a strong predictor of adherence at both time points (p < 0.001 for 4 and 16 weeks; one way ANOVA).


CONCLUSIONS
The SOC category determined at baseline correlated poorly with subsequent medication adherence in our indigent, HIV-infected patient population. Prediction of adherence based on SOC after treatment initiation may provide a better estimate of adherence behavior. Recognition of this limitation may help clinicians more accurately interpret predicted adherence behavior from self-report instruments.
Rathbun
R Chris
RC
College of Pharmacy, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA. Chris-Rathbun@ouhsc.edu
Farmer
Kevin C
KC
Lockhart
Staci M
SM
Stephens
Johnny R
JR
D000328:Adult; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D023241:Antiretroviral Therapy, Highly Active; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D016014:Linear Models; D008297:Male; D010349:Patient Compliance / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D013997:Time Factors
D019380:Anti-HIV Agents