Limits...
Predictive validity of a brief antiretroviral adherence index: retrospective cohort analysis under conditions of repetitive administration.

Mathews WC, Barker E, Winter E, Ballard C, Colwell B, May S - AIDS Res Ther (2008)

Bottom Line: Newer antiretroviral (ARV) agents have improved pharmacokinetics, potency, and tolerability and have enabled the design of regimens with improved virologic outcomes.In the final generalized estimating equations (GEE) logistic regression model the adjusted odds ratio for time-updated adherence score was 0.17(score >/= 5) (0.05-0.66) [reference: <5].The survey can be used for identification of sub-optimal adherence with subsequent appropriate intervention.

View Article: PubMed Central - HTML - PubMed

Affiliation: UCSD Owen Clinic, UCSD Medical Center, Mail Code 8681, 200 W, Arbor Dr,, San Diego, CA 92103, USA. cmathews@ucsd.edu

ABSTRACT

Background: Newer antiretroviral (ARV) agents have improved pharmacokinetics, potency, and tolerability and have enabled the design of regimens with improved virologic outcomes. Successful antiretroviral therapy is dependent on patient adherence. In previous research, we validated a subset of items from the ACTG adherence battery as prognostic of virologic suppression at 6 months and correlated with adherence estimates from the Medication Event Monitoring System (MEMS). The objective of the current study was to validate the longitudinal use of the Owen Clinic adherence index in analyses of time to initial virologic suppression and maintenance of suppression.

Results: 278 patients (naïve n = 168, experienced n = 110) met inclusion criteria. Median [range] time on the first regimen during the study period was 286 (30 - 1221) days. 217 patients (78%) achieved an undetectable plasma viral load (pVL) at median 63 days. 8.3% (18/217) of patients experienced viral rebound (pVL > 400) after initial suppression. Adherence scores varied from 0 - 25 (mean 1.06, median 0). The lowest detectable adherence score cut point using this instrument was >/= 5 for both initial suppression and maintenance of suppression. In the final Cox model of time to first undetectable pVL, controlling for prior treatment experience and baseline viral load, the adjusted hazard ratio for time updated adherence score was 0.36(score >/= 5) (95% CI: 0.19-0.69) [reference: <5]. In the final generalized estimating equations (GEE) logistic regression model the adjusted odds ratio for time-updated adherence score was 0.17(score >/= 5) (0.05-0.66) [reference: <5].

Conclusion: A brief, longitudinally administered self report adherence instrument predicted both initial virologic suppression and maintenance of suppression in patients using contemporary ARV regimens. The survey can be used for identification of sub-optimal adherence with subsequent appropriate intervention.

No MeSH data available.


Related in: MedlinePlus

Screen shot of adherence instrument.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2543036&req=5

Figure 1: Screen shot of adherence instrument.

Mentions: First, adherence score distributions in the current (Figure 2) and previous study were highly skewed, with most observations clustered in a range reflecting good adherence and the remainder of observations distributed in the long tail of the distribution reflecting poorer adherence. The clustering of observations toward the excellent adherence end of the distribution creates ceiling effects [4]. Others have noted the same phenomenon for other self report measures [5-8]. The clustering of scores toward excellent adherence likely represents a mixture of responses from truly adherent patients and from others exhibiting social desirability bias [9]. Simoni et al have commented on approaches to minimize both ceiling effects and social desirability bias in adherence assessment [10]. Comparison of self report scores to independent and hopefully more objective measures of adherence (e.g. pharmacy refill data, pill counts, EDM) offer an opportunity to assess the effect of social desirability bias. In other contexts, the use of measures designed to measure social desirability as a construct have been used as covariates to explain self reported health behaviors subject to such response bias [11,12]. With regard to ceiling effects not contaminated by social desirability bias, designing items to capture more challenging aspects of adherence behavior, such as timing of doses or dose taking at inconvenient times (e.g. at work, on weekends, or in the presence of persons not knowing the patient's diagnosis), has been recommended to mitigate the strict ceiling commonly observed in self reported adherence. It should be noted, however, that our instrument included three items (Figure 1: items 2–4) dealing with such recommended approaches.


Predictive validity of a brief antiretroviral adherence index: retrospective cohort analysis under conditions of repetitive administration.

Mathews WC, Barker E, Winter E, Ballard C, Colwell B, May S - AIDS Res Ther (2008)

Screen shot of adherence instrument.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2543036&req=5

Figure 1: Screen shot of adherence instrument.
Mentions: First, adherence score distributions in the current (Figure 2) and previous study were highly skewed, with most observations clustered in a range reflecting good adherence and the remainder of observations distributed in the long tail of the distribution reflecting poorer adherence. The clustering of observations toward the excellent adherence end of the distribution creates ceiling effects [4]. Others have noted the same phenomenon for other self report measures [5-8]. The clustering of scores toward excellent adherence likely represents a mixture of responses from truly adherent patients and from others exhibiting social desirability bias [9]. Simoni et al have commented on approaches to minimize both ceiling effects and social desirability bias in adherence assessment [10]. Comparison of self report scores to independent and hopefully more objective measures of adherence (e.g. pharmacy refill data, pill counts, EDM) offer an opportunity to assess the effect of social desirability bias. In other contexts, the use of measures designed to measure social desirability as a construct have been used as covariates to explain self reported health behaviors subject to such response bias [11,12]. With regard to ceiling effects not contaminated by social desirability bias, designing items to capture more challenging aspects of adherence behavior, such as timing of doses or dose taking at inconvenient times (e.g. at work, on weekends, or in the presence of persons not knowing the patient's diagnosis), has been recommended to mitigate the strict ceiling commonly observed in self reported adherence. It should be noted, however, that our instrument included three items (Figure 1: items 2–4) dealing with such recommended approaches.

Bottom Line: Newer antiretroviral (ARV) agents have improved pharmacokinetics, potency, and tolerability and have enabled the design of regimens with improved virologic outcomes.In the final generalized estimating equations (GEE) logistic regression model the adjusted odds ratio for time-updated adherence score was 0.17(score >/= 5) (0.05-0.66) [reference: <5].The survey can be used for identification of sub-optimal adherence with subsequent appropriate intervention.

View Article: PubMed Central - HTML - PubMed

Affiliation: UCSD Owen Clinic, UCSD Medical Center, Mail Code 8681, 200 W, Arbor Dr,, San Diego, CA 92103, USA. cmathews@ucsd.edu

ABSTRACT

Background: Newer antiretroviral (ARV) agents have improved pharmacokinetics, potency, and tolerability and have enabled the design of regimens with improved virologic outcomes. Successful antiretroviral therapy is dependent on patient adherence. In previous research, we validated a subset of items from the ACTG adherence battery as prognostic of virologic suppression at 6 months and correlated with adherence estimates from the Medication Event Monitoring System (MEMS). The objective of the current study was to validate the longitudinal use of the Owen Clinic adherence index in analyses of time to initial virologic suppression and maintenance of suppression.

Results: 278 patients (naïve n = 168, experienced n = 110) met inclusion criteria. Median [range] time on the first regimen during the study period was 286 (30 - 1221) days. 217 patients (78%) achieved an undetectable plasma viral load (pVL) at median 63 days. 8.3% (18/217) of patients experienced viral rebound (pVL > 400) after initial suppression. Adherence scores varied from 0 - 25 (mean 1.06, median 0). The lowest detectable adherence score cut point using this instrument was >/= 5 for both initial suppression and maintenance of suppression. In the final Cox model of time to first undetectable pVL, controlling for prior treatment experience and baseline viral load, the adjusted hazard ratio for time updated adherence score was 0.36(score >/= 5) (95% CI: 0.19-0.69) [reference: <5]. In the final generalized estimating equations (GEE) logistic regression model the adjusted odds ratio for time-updated adherence score was 0.17(score >/= 5) (0.05-0.66) [reference: <5].

Conclusion: A brief, longitudinally administered self report adherence instrument predicted both initial virologic suppression and maintenance of suppression in patients using contemporary ARV regimens. The survey can be used for identification of sub-optimal adherence with subsequent appropriate intervention.

No MeSH data available.


Related in: MedlinePlus