Nonadherence to cardiovascular medications such as statins is a common, important
problem. Clinicians currently rely on intuition to identify medication nonadherence.
The visit-to-visit variability (VVV) of low-density lipoprotein (LDL) cholesterol
might represent an opportunity to identify statin nonadherence with greater accuracy.
We examined the clinical and pharmacy data from 782 members of the Boston Medical
Center Health Plan, seen at either the Boston Medical Center or its affiliated community
health centers, who were taking statins and had ≥3 LDL cholesterol measurements from
2008 to 2011. The LDL cholesterol VVV (defined by the within-patient SD) was categorized
into quintiles. Multivariate logistic regression models were generated with statin
nonadherence (defined by the standard 80% pharmacy refill-based medication possession
ratio threshold) as the dependent variable. The proportion of statin nonadherence
increased across the quintiles of LDL cholesterol VVV (64.3%, 71.2%, 89.2%, 92.3%,
91.7%). Higher quintiles of LDL cholesterol VVV had a strong positive association
with statin nonadherence, with an adjusted odds ratio of 3.4 (95% confidence interval
1.7 to 7.1) in the highest versus lowest quintile of LDL cholesterol VVV. The age-
and gender-adjusted model had poor discrimination (C-statistic 0.62, 95% confidence
interval 0.57 to 0.67), but the final adjusted model (age, gender, race, mean LDL
cholesterol) demonstrated good discrimination (C-statistic 0.75, 95% confidence interval
0.71 to 0.79) between the adherent and nonadherent patients. In conclusion, the VVV
of LDL cholesterol demonstrated a strong association with statin nonadherence in a
clinic setting. Furthermore, a VVV of LDL cholesterol-based model had good discrimination
characteristics for statin nonadherence. Research is needed to validate and generalize
these findings to other populations and biomarkers.
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Article info
Publication history
Published online: February 22, 2013
Accepted:
January 21,
2013
Received in revised form:
January 21,
2013
Received:
October 2,
2012
Footnotes
This work was supported by grant RC2HL101628-01 (to N. R. Kressin and W. G. Adams, primary investigators). Dr. Kressin was also supported by Research Career Scientist award RCS 02-066-1 from the Health Services Research and Development Service, Department of Veterans Affairs (Washington, DC). The present study was also supported by Patient-Oriented Mentored Scientist Award K23DK081665 through the National Institute of Diabetes, Digestive, and Kidney Diseases (Bethesda, Maryland) (to D. M. Mann) and grant UL1-TR000157 from the Boston University's Clinical and Translational Institute (Boston, Massachusetts).
Dr. Mann had full access to all the data in the present study and takes responsibility for the integrity of the data and accuracy of the data analysis. The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.
See page 1442 for disclosure information.
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© 2013 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
