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The American Journal of Managed Care March 2013
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Measuring Concurrent Oral Hypoglycemic and Antidepressant Adherence and Clinical Outcomes
Hillary R. Bogner, MD, MSCE; Heather F. de Vries, MSPH; Alison J. O'Donnell, BA; and Knashawn H. Morales, ScD
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Measuring Concurrent Oral Hypoglycemic and Antidepressant Adherence and Clinical Outcomes

Hillary R. Bogner, MD, MSCE; Heather F. de Vries, MSPH; Alison J. O'Donnell, BA; and Knashawn H. Morales, ScD
Self-reported adherence tended to overestimate medication adherence compared with electronic monitoring. Electronic monitoring of oral hypoglycemic agents but not self-reported adherence predicted glycemic control.
In the second phase, using adherence dichotomized at a threshold of 80%, our goal was to examine the relationship of >80% adherence, measured using both self-reported adherence and electronic monitoring, with clinical outcomes. As recommended by the American Diabetes Association clinical guidelines, an indicator of whether a participant achieved A1C <7% at 12 weeks was calculated.30 Depression remission was defi ned by a PHQ-9 score <5 at follow-up.32 We employed logistic regression to assess the relationship between the categorical diabetes outcome and adherence to the oral hypoglycemic agent and to assess the relationship between depression remission and adherence to the antidepressant. For both models, we report the odds ratio and 95% confi dence interval. Our final multivariate logistic regression models were adjusted for potentially influential variables including age, ethnicity, gender, marital status, educational attainment, functional status, frequency of medication administration, number of medications, number of medical conditions, cognitive status, intervention condition, and baseline clinical outcome. Analyses were conducted using SAS version 9.2 (SAS Institute, Inc, Cary, North Carolina).

RESULTS

Sample Characteristics


The CONSORT flow diagram for flow of participants through the trial has been published elsewhere.19 Baseline patient characteristics are shown in Table 1. A total of 138 patients (76.7%) were prescribed an oral hypoglycemic agent once a day, 40 (22.2%) twice a day, 1 (0.6%) 3 times a day, and 1 (0.6%) 4 times a day. A total of 160 patients (88.9%) were prescribed an antidepressant once a day, 19 (10.6%) twice a day, and 1 (0.6%) 3 times a day.

Adherence

Figure 2 depicts the mean adherence to oral hypoglycemic agents (upper panel) and to antidepressants (bottom panel) assessed with self report and electronic monitoring using the MEMS at baseline, 6 weeks, and 12 weeks. Table 2 presents the kappa coefficient results for the proportion of patients who were >80% adherent by each method and for oral hypoglycemic agents and antidepressants separately. At baseline and 6 weeks, self-reported adherence and electronic monitoring of adherence showed slight agreement (eg, kappa = 0.155, P = .038 for oral hypoglycemic agents at 6 weeks and kappa = 0.179, P = .009 for antidepressants at 6 weeks). At 12 weeks, self-reported adherence and electronic monitoring of adherence showed fair agreement (kappa = 0.213, P = .004 for oral hypoglycemic agents and kappa = 0.380, P <.001 for antidepressants). At 12 weeks, adherence rates for oral hypoglycemic agents measured with self report and electronic monitoring were 72.8% versus 65.6%, respectively. At 12 weeks, adherence rates for antidepressants measured with self report and electronic monitoring were 70.6% versus 58.3%, respectively.

Clinical Outcomes

At 12 weeks, 81 patients (45%) had a PHQ-9 <5 indicating depression remission and 110 (61.1%) had A1C <7%. Table 3 examines the relationship of clinical outcomes, A1C <7%, and depression remission at 12 weeks, with >80% adherence, measured both using self-reported adherence and electronic monitoring. Patients who achieved >80% adherence to oral hypoglycemic agents measured with electronic monitoring were more likely to achieve A1C <7% compared with patients who did not achieve >80% adherence at 12 weeks (adjusted odds ratio [OR] = 3.52, 95% confidence interval [CI] 1.07-11.57). Patients who achieved >80% adherence to oral hypoglycemic agents measured using self-reported adherence were no more likely to achieve A1C <7% compared with patients who did not achieve >80% adherence at 12 weeks (adjusted OR = 0.94, 95% CI 0.33-2.66). Patients who achieved >80% adherence to antidepressants measured with electronic monitoring were more likely to achieve remission of depression in comparison with patients who did not achieve >80% adherence at 12 weeks (PHQ-9 <5, unadjusted OR= 1.88, 95% CI 1.03-3.46), but the results did not remain significant in the final model after adjusting for age, ethnicity, gender, marital status, educational attainment, functional status, frequency of medication administration, number of medications, number of medical conditions, cognitive status, intervention condition, and baseline clinical outcome (PHQ-9 <5, adjusted OR = 0.76, 95% CI 0.27-2.20).

DISCUSSION

The principal finding of this study is that self-reported adherence overestimates adherence over time compared with electronic monitoring. Patients who were adherent to oral hypoglycemic agents assessed using electronic monitoring had improved glycemic control at the end of the study period. However, self-reported adherence did not predict clinical outcomes for T2DM. Adherence to oral hypoglycemic agents was slightly greater than adherence to antidepressants in our sample of patients simultaneously prescribed oral hypoglycemic agents and antidepressants. Self-reported adherence and electronic monitoring for antidepressants did not predict depression remission.

Before discussing our findings, the results must be considered in the context of potential limitations. First, our sample was obtained from patients who received care at 3 primary care practices that might not be representative of most primary care sites. However, the 3 practices varied in size and were diverse and probably similar to other primary care practices in the region. Second, the healthy adherer bias is an important issue when examining any association of adherence with clinical outcomes. The patients who achieved A1C <7% may follow healthier lifestyles other than just taking their medications. We do not have information on lifestyle factors such as diet and physical activity. Third, we chose to use electronic monitoring as our reference standard for our measure of adherence. While electronic monitoring may overestimate adherence because the events captured by it (date/time of bottle opening) do not ensure medication ingestion, electronic monitoring has been shown to have a low failure rate and may be more sensitive than other adherence measures.21,37 Fourth, self-reported adherence was assessed by non-clinician research assistants and therefore might differ from self-reported adherence assessed by a clinician. Fifth, for some medications the 80% threshold has not been assessed. However, patients were taking a broad range of antidepressants and oral hypoglycemic agents in this study and the 80% threshold has been assessed for the majority of these medications.16-18,21,36 Sixth, the Hawthorne effect may have influenced patient behavior, making patients more likely to adhere to their medical regimens than they would if they were not participating in the study.38 However, even with careful monitoring of adherence in the study setting, adherence rates have been shown to be poor in numerous settings.39-41 Finally, patients with significantly elevated A1C are an important target for resources and intervention and our study population did not consist solely of this patient profile. However, while patients may experience periods of stringent regimen adherence, relapse into poorer control is common and thus targeting patients with a range of glycemic control is essential and highly applicable to real-world settings. As a result, patients with diabetes and a range of A1C scores have been the target of many adherence investigations and interventions. Despite these limitations our results deserve attention because this is the first known study to compare adherence assessment using self-reported adherence and electronic monitoring of adherence for both oral hypoglycemic agents and antidepressants. Adherence to treatment is essential for improving care among patients with comorbid diabetes and depression.42 Integrating management of physical and mental health has special significance in the primary care setting where patients commonly present for treatment of both physical and mental health.

Participants consistently overestimated adherence with selfreport compared with electronic monitoring. In the literature, reasons for overestimation of self-reported adherence include poor physician-patient communication, lack of comprehension of required medication-taking regimens, cognitive decline, social desirability of responses, interviewing conditions, and data collection methods.43,44 In our study, overestimation of adherence with self-report may be the result of patients truly believing that they are taking their medications as prescribed. Prior work has found that patients may believe they took their medication while unknowingly having missed prescribed treatment regimens due to factors such as recall time frame, age, medical comorbidity, and interviewing circumstances.45 Of note, adherence measured using electronic monitoring increased throughout the course of the study while the overestimation of self-reported adherence in relation to electronic monitoring slightly decreased. The former is likely due to the effect of the intervention. The latter may be explained by social desirability or the “desire to please,” which is a tendency of individuals to respond in a manner consistent with societal norms or beliefs46 and has also been identified as a major cause of overstated medication adherence in self-reported adherence assessments.47 As the study progressed, participants became increasingly aware that their adherence was consistently and accurately being monitored, thus making it more socially desirable to improve the accuracy of their reporting.

Our results were not wholly consistent with our initial hypotheses. We found that patients who were adherent to oral hypoglycemic agents assessed using electronic monitoring had significantly improved glycemic control compared with patients who were nonadherent at the end of the study period. This is consistent with previous findings that found an association between greater electronic monitoring adherence and improved diabetes outcomes in primary care patients.48 However, we did not find an association between electronic monitoring and outcomes for depression. Our sample did comprise a large portion of participants with minor depression, and findings regarding the efficacy for antidepressant use for the treatment of minor depression are inconclusive. While some studies have indicated that antidepressants may reduce depressive symptoms in minor depression,49,50 a recent systematic review of studies to examine the efficacy of antidepressants for the treatment of minor depression reported that there is unlikely to be a clinically important advantage for antidepressants over placebo in individuals with minor depression.51

We found adherence to oral hypoglycemic agents appeared to be greater than adherence to antidepressants, highlighting differing medication taking–related behaviors for physical health conditions compared with mental health conditions as well as being consistent with previous research suggesting that the rate of medication adherence among patients with physical disorders is greater than the rate of antidepressant adherence.2 This may be due to a myriad of factors such as greater perceived stigma associated with medications for mental disorders,52 systemic factors such as insurance coverage,53 or patient-provider dynamics in which medical comorbidity may complicate the management of mental illness.54

 
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