Modes of Delivery for Interventions to Improve Cardiovascular Medication Adherence
Published Online: December 16, 2010
Sarah L. Cutrona, MD, MPH; Niteesh K. Choudhry, MD, PhD; Michael A. Fischer, MD, MPH; Amber Servi, BA; Joshua N. Liberman, PhD; Troyen A. Brennan, MD, JD; and William H. Shrank, MD, MSHS
Nonadherence to essential chronic medication therapy for cardiovascular disease and diabetes is common, leading to substantial morbidity, mortality, and healthcare costs.1-3 Evidence- based efforts to improve adherence are needed. Previous studies have demonstrated the effectiveness of reduced dosing demands and complex, multifactorial interventions,4,5 but there is little evidence available comparing modes of delivery for adherence interventions.
Evidence-based information on modes of delivery would enhance the construction of adherence interventions in several domains: the communication channel (eg, written, electronic, phone, in person), the purveyor of information (eg, lay person, pharmacist, physician), and the optimal setting (hospital, home, pharmacy, clinic). The mode of delivery is closely linked to an intervention’s cost and therefore to its long-term viability. Careful consideration of the comparative efficacy and intensity of different approaches is needed to develop evidence-based strategies.
We conducted a systematic review of interventions that sought to improve adherence to medications for cardiovascular disease and diabetes, a cardiovascular disease equivalent. We focused on the mechanism of information transfer to patients. By evaluating the effects of (1) the purveyor of information, (2) the channel of information, and (3) the setting of transfer, we offer to payers, providers, and policy makers additional guidance on the development of adherence interventions.
We performed a systematic search of articles published in peer-reviewed, healthcare-related journals between 1966 and December 31, 2008. The search was performed using MEDLINE and EMBASE, with the help of a professional librarian. We limited our search to randomized controlled trials.
We used search terms related to the type of study (randomized controlled trial), adherence (ie, “adherence” OR “compliance” OR “medication adherence” or “treatment adherence”), prescription drugs (ie, “drug” OR “medication” OR “antihypertensive” OR “antihyperlipidemic” OR “hypoglycemic agents”), and cardiovascular disease and diabetes (myocardial infarction, coronary heart disease, heart failure; hypertension; hyperlipidemia; and diabetes). Articles with at least 1 search term in 3 of the main categories (study type AND adherence AND either drug OR disease) met criteria for the title/abstract review (see the eAppendix at www.ajmc.com).
Search terms and parameters were adjusted for both databases while maintaining a common overall architecture. Search results from MEDLINE and EMBASE were combined and screened for duplicate entries.
Studies were included if they reported the results of randomized controlled trials that examined interventions to improve adherence to medications used for the prevention or treatment of cardiovascular disease or diabetes. Studies were limited to adult subjects (aged ≥18 years) in either the outpatient setting or at the inpatient/ outpatient transition. Data were gathered on outpatient adherence for all patients. Studies were excluded if they described an intervention characterized by regimen simplification (either unit-of-use packaging or changes in dose frequency or formulation), as they could not be placed into the study categorization, and previous studies have demonstrated their effectiveness.4 Studies were excluded if they were written in a language other than English. Those with a duration of less than 24 weeks were excluded because cardiovascular medications typically require long-term adherence.
After exclusions, 51 articles (Figure) were classified by the mode of delivery of the intervention. Person-independent interventions included (1) mailed, faxed, or hand-distributed interventions and (2) interventions delivered via electronic system. Person-dependent interventions included (1) interventions delivered via nonautomated phone calls and (2) in-person interventions (classified based on site of delivery, ie, home, work site, pharmacy, clinic, or hospital). Persondependent interventions were further classified based on the level of training required of the person administering the intervention: (1) trained lay person, (2) nurse, (3) pharmacist, (4) physician, or (5) not specified.
For those studies that incorporated 2 or more modes of intervention, we assigned categories based on what appeared to be the main mode of intervention. Where categories appeared to be equivalent, we assigned priority in the following order: person dependent (in person, followed by phone) and person independent (electronic system, followed by mailed, faxed, or hand distributed).
Data were extracted by 2 investigators (SLC, WHS) with disagreements resolved by consensus. We assessed a number of variables related to the organization and outcome of studies, including the study design, setting, characteristics of population studied, the number of participants, characteristics of intervention, methods used to measure medication adherence, clinical outcomes, and medication adherence outcomes. We report confidence intervals (CIs) when available and P values when no CIs were available.
Our search retrieved a total of 6550 articles. Of these articles, 168 were reviewed in full and 51 met inclusion criteria6-56 (Figure, Table 1, Table 2). The majority (55%) of interventions were aimed at subjects with hypertension. Other patient populations studied included those with diabetes (8%), coronary artery disease (8%), congestive heart failure (14%), and dyslipidemia (10%); 6% of the studies evaluated patients with a mix of cardiovascular and noncardiovascular diseases.
Person-Independent Interventions: Mailed, Faxed, or Hand-Distributed Material
There were 3 studies6-8 in which the main intervention was delivered via mail, fax, or hand distribution of paper or video information; 1 was successful.6 Smith et al followed 907 patients after discharge from a hospital stay for myocardial infarction; 2 letters sent to patients and to primary care providers describing the importance of beta-blocker use yielded improved adherence as measured by pharmacy claims data. Patients receiving mailings were 17% more likely to have 80% of days covered (relative risk = 1.17; 95% CI = 1.02, 1.29). The 2 unsuccessful studies described direct patient mailings of written information on hypertension7 or video information on 1 of 4 medications (2 blood pressure agents, an antihyperlidemic, and transdermal estrogen).8 Takala defined adherent patients as those still under treatment after 2 years,7 and Powell and Edgren studied mean medication possession ratios.8
Person-Independent Interventions: Electronic Systems
There were 6 studies9-14 that examined a range of electronic interventions, including use of electronic pillboxes with programmable reminders, automated phone calls with interactive components, computer-generated individualized interventions, and home automatic blood pressure monitoring. Overall, this group included more positive studies than the mailed/faxed/hand-delivered group (4 out of 6 showed improved adherence).
Rosen et al14 studied 33 people with diabetes whose baseline adherence was less than 80%. This study tested use of electronic pill caps with a time display and programmable beeper compared with electronic pill caps alone. Participants with programmable beeper pill caps showed improved adherence (80% intervention vs 60% control; P = .017).
Friedman et al10 and Piette et al13 studied the effect of automated phone calls. Friedman and colleagues followed 299 hypertensive patients, randomizing patients to an interactive computer-based home telemonitoring system versus usual care. Patients called in weekly, shared information by phone regarding automated blood pressure readings and adherence, and received targeted education and motivational counseling (all automated), with responses forwarded to doctors. Adherence, measured by pill count, was not significantly different between groups in unadjusted analysis; adjustment for age, sex, and baseline adherence yielded significant differences (17.7% adherence in intervention group vs 11.7% in control group; P = .03). Piette et al randomized 280 patients to biweekly automated interactive phone calls with structured messages that were adjusted based on patient responses, followed by targeted nurse calls versus usual care. Differences from Friedman et al’s intervention include outgoing calls to patients (Friedman et al required patients to call in) and limited nonautomated phone follow-up. Piette and colleagues found that intervention patients were “substantially less likely to report adherence problems” (based on self-report using modified Morisky scale) (P = .003, no adherence percentages given) but did not provide baseline adherence (56% reported “any medication problem” at baseline).
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