Article

Measures of Adherence to Oral Hypoglycemic Agents at the Primary Care Clinic Level The Role of Risk Adjustment

Northwest Center for Outcomes Research in Older Adults, VA Puget Sound Health Care System, WA 98101, USA.
Medical care (Impact Factor: 2.94). 02/2012; 50(7):591-8. DOI: 10.1097/MLR.0b013e318249cb74
Source: PubMed

ABSTRACT Prior research found that in the Veterans Affairs health care system (VA), the proportion of patients adherent to oral hypoglycemic agents varies from 50% to 80% across primary care clinics. This study examined whether variation in patient and facility characteristics determined those differences.
Retrospective cohort study of 444,418 VA primary care patients with diabetes treated in 559 clinics in fiscal year (FY) 2006-2007. Patients' adherence to each oral hypoglycemic agent was computed for the first 3 months of FY2007, and averaged across agents to produce an adherence score for the patient's overall regimen. Patients with an adherence score over 0.8 were defined as adherent. Risk adjustment used hierarchical logistic regression accounting for patient factors and facility effects by clustering patients within clinics and clinics within parent VA medical centers. We then assessed the influence of risk adjustment using observed-to-expected (O/E) ratios computed for each clinic.
The mean unadjusted proportion of adherent patients in clinics was 0.715 (interdecile range 0.559-0.826). The percent variation in patient's likelihood of being adherent explained at the patient, clinic, and parent VA medical center levels was 2.94%, 0.27%, and 0.76%, respectively. The mean clinic-level observed-to-expected ratio was 1.001 (interdecile range 0.975-1.027).
The variation in the proportion of patients adherent across clinics remained large after risk adjustment. As patient and facility effects explained only 4% of the variance in adherence, comparing clinics based on unadjusted scores is a reasonable starting point unless more predictive patient, provider, and facility factors are identified.

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    • "In a study of records from more than 56,000 veterans with type 2 diabetes taking OADs (years 2000–2002), 23% of patients were categorized as non-adherent, as defined by a medication possession ratio (MPR) <80% after 1 year [80]. A later re-evaluation of the VA database (years 2005–2007) demonstrated a somewhat higher rate of non-adherence (30%) using the 1-year MPR (N = 444,418) [81]. One study that reviewed the medical literature for data on adherence (years 2000–2005) reported similar results, showing that 42% of patients had a 1-year MPR <80% (35 studies) [82]. "
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    • "Not only are individual factors weakly predictive on their own, multivariable models do not predict or explain more than a fraction of the massive burden of non-adherence observed in population studies.42,43 For example, Wong et al could explain less than 4% of all cases of non-adherence (measured from prescription refill databases) using available patient-level and clinic-level factors from administrative data sources among 444,418 patients with diabetes registered in the National Veterans Affairs database in the US.43 "
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    • "The final study sample included 280,603 diabetes patients who received care from 196 primary clinics for which data were also available from the primary care survey. These patients were a subset of a sample documented in a prior study [17]. "
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    ABSTRACT: Background Although oral hypoglycemic agents (OHAs) are an essential element of therapy for the management of type 2 diabetes, OHA adherence is often suboptimal. Pharmacists are increasingly being integrated into primary care as part of the move towards a patient-centered medical home and may have a positive influence on medication use. We examined whether the presence of pharmacists in primary care clinics was associated with higher OHA adherence. Methods This retrospective cohort study analyzed 280,603 diabetes patients in 196 primary care clinics within the Veterans Affairs healthcare system. Pharmacists presence, number of pharmacist full-time equivalents (FTEs), and the degree to which pharmacy services are perceived as a bottleneck in each clinic were obtained from the 2007 VA Clinical Practice Organizational Survey—Primary Care Director Module. Patient-level adherence to OHAs using medication possession ratios (MPRs) were constructed using refill data from administrative pharmacy databases after adjusting for patient characteristics. Clinic-level OHA adherence was measured as the proportion of patients with MPR >= 80%. We analyzed associations between pharmacy measures and clinic-level adherence using linear regression. Results We found no significant association between pharmacist presence and clinic-level OHA adherence. However, adherence was lower in clinics where pharmacy services were perceived as a bottleneck. Conclusions Pharmacist presence, regardless of the amount of FTE, was not associated with OHA medication adherence in primary care clinics. The exact role of pharmacists in clinics needs closer examination in order to determine how to most effectively use these resources to improve patient-centered outcomes including medication adherence.
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