Real-Time Compliance Data to Help Define Optimal Drug Regimens

Interrelationships of quality of life, compliance, clinical outcomes and life satisfaction: a cross-sectional study on hypertensive geriatrics

OBJECTIVE

(i) To assess quality of life (QoL) profiles in hypertensive geriatrics with SF-36; (ii) to assess the compliance of geriatrics to medications; (iii) to estimate clinical outcomes (reduction in systolic and diastolic blood pressure); (iv) to assess life satisfaction and (v) to explore the interrelationships of QoL, compliance, clinical outcomes and life satisfaction in hypertensive geriatrics.

METHOD

Fifty-nine hypertensive geriatric patients in cardiology and 65 Plus clinics in West Virginia Hospitals were studied.

RESULTS

Age showed a significant negative correlation with physical functioning (r = 0.339, P< or =0.0127) and physical role (r=0.335, P< or =0.0148). The physical role facet of SF-36 is correlated with life satisfaction in geriatrics (r = 0.316, P < or =0.0219). A regression analysis (backward stepwise) not including bodily pain (BP) and general health (GH) resulted in a model explaining 22.3% of variance (n = 54, F = 2.252, P < or = 0.0543). Physical role (P < or = 0.0084) and mental health facets (P< or = 0.0184) of SF-36 emerged as the predictors of life satisfaction in elderly hypertensive patients. Emotional role functioning (P < or = 0.0257) and social functioning (P < or = 0.0033) scores predicted levels of diastolic blood pressure in elderly hypertensive patients. However, all eight concepts of SF-36 failed to predict compliance behaviour in geriatrics (n = 53, P < or = 0.6913, R2= 0.110).

Derivation of adherence metrics from electronic dosing records

Numerous adherence variables have been created from electronic dosing records hindering synthesis of the vast body of adherence research. To elucidate the mathematical foundation for electronic adherence monitoring and to understand how diverse electronic adherence metrics are related to each other and the underlying construct of adherence behavior. Several representative adherence metrics are derived mathematically and their relationship to the underlying consumption (or dosing event) rate analyzed. Data from a 3-month study of 286 individuals on single-drug antihypertensive therapy are then used to empirically study the statistical properties of several of these electronic adherence metrics. As suggested by their common link to the consumption (or dosing event) rate, the analyzed electronic adherence metrics were generally strongly correlated (r <- .6 and > .4). The lowest correlation (r = .15) involved the ratio of the observed number of doses to the recommended number (called average adherence), which tended to emphasize quantity consumed, and the ratio of the observed to maximum mean squared rate deviation (MSRD ratio), which focused more on dose timing. Despite their different formulations, electronic adherence variables are generally closely correlated. Adherence metrics that average the consumption rate over multiple doses (by summing up the number of doses and dividing by the monitored time) may be less sensitive to short-term fluctuations in medication intake. Metrics that are more sensitive to timing variability may thus be preferable when timing as well as quantity of dosing are of interest.

Characterizing patterns of drug-taking behavior with a multiple drug regimen in an AIDS clinical trial

OBJECTIVE

To characterize drug-taking behavior using continuous electronic monitoring in an AIDS clinical trial.

SETTING

This was a substudy of AIDS Clinical Trials Group (ACTG) protocol 175, a phase II/III study of dideoxynucleoside monotherapy versus combination therapy in asymptomatic HIV-positive subjects. Participants were required to comply with regimens containing zidovudine, zalcitabine and didanosine, or matching placebos; the total daily pill count was 16.

DESIGN

For participants at two ACTG 175 sites, electronic devices were used to monitor drug-taking behavior of all study medications over a period of approximately 90 days.

MEASUREMENTS

Four indices of drug-taking behavior were calculated and their distributions and relationship to the prescribed regimen were examined.

RESULTS

Data from 41 subjects were analyzed. Of the prescribed doses of zidovudine, zalcitabine and didanosine, 88, 84 and 82%, respectively, were taken. Of these, 55, 66 and 79%, respectively, were taken at the prescribed dosing frequency. The median percentage of days on which participants failed to take any of the doses was 2-5%. There was a trend towards lower adherence in the combination therapy arms compared with those assigned to receive monotherapy. In this analysis, older patients demonstrated better adherence, although patient characteristics, in general, were poorly predictive of adherence.

CONCLUSION

Drug-taking behavior for all three active study medications differed from that prescribed. One result of this erratic adherence was that study participants sustained little antiretroviral effect during more than 25% of the monitoring period.

Drug compliance in pediatrics. Clinical and research issues

Noncompliance with therapy is widespread in children, with potentially important implications in clinical practice and the research setting. Compliance with therapy is a critical element in the success of therapy, that is, for an efficacious medication to be effective, it must be taken. Demonstration of patterns of drug adherence and the association between compliance and outcome in clinical practice have been facilitated by the recent introduction of electronic monitoring of medication compliance. Determinants of drug compliance, optimal measurement of compliance, and strategies to improve compliance remain to be further explored in children. Given the prevalence of and the potential consequence of noncompliance, pediatricians must have a high index of suspicion of noncompliance to provide the best possible care to their patients.

Prediction and optimisation of the antihypertensive response to nifedipine

The predictability of the long term antihypertensive response to nifedipine in individual patients has been assessed by an analysis based upon the concentration-effect parameters defined following the first dose administration of 20 mg nifedipine (Retard). The predicted and measured reductions in blood pressure during steady state nifedipine treatment were compared for the trough and peak responses and there was reasonable agreement for the group of patients as a whole. However, when the measured and predicted blood pressure profiles were compared for each individual patient there was close agreement for the majority of patients but there were significant discrepancies in a few cases. Further analysis of the steady state concentrations in these cases revealed that there was no change in their responsiveness to nifedipine and that discrepancies were directly attributable to inappropriate compliance with the drug regimen. The analysis was further extended to simulate the blood pressure responses to alternative fixed dosage regimens. Assessment of these simulations suggests that blood pressure control with nifedipine Retard is significantly improved by three times daily drug administration.