Abstract
Purpose
The aim of this study was to test whether patient medication adherence, a modifiable risk factor obtainable at hospital admission, predicts readmission within 30 days.
Patients and methods
We used a retrospective cohort study design to test whether patient medication adherence to all chronic medications, as determined by the 4-item Morisky Medication Adherence Scale (MMAS-4) administered by a pharmacist at the time of hospital admission, predicts 30-day readmissions. We compared readmission rates among 385 inpatients who had their adherence assessed from February 1, 2013, to January 31, 2014. Multiple logistic regression was used to examine the benefit of adding medication adherence to previously published variables that have been shown to predict 30-day readmissions.
Results
Patients with low and intermediate adherence (combined) had readmission rates of 20.0% compared to a readmission rate of 9.3% for patients with high adherence (P=0.005). By adding MMAS-4 data to previously published variables that have been shown to predict 30-day readmissions, we found that patients with low and intermediate medication adherence had an adjusted 2.54-fold higher odds of readmission compared to those in patients with high adherence (95% confidence interval [CI]: 1.32–4.90, P=0.005). The model’s predictive power, as measured by the c-statistic, improved from 0.65 to 0.70 after adding adherence.
Conclusion
Because medication adherence assessed at hospital admission was independently associated with 30-day readmission risk, it offers potential for targeting interventions to improve adherence.
Acknowledgments
The authors acknowledge the contributions of Donald Morisky, professor of the Department of Community Health Sciences at the UCLA Fielding School of Public Health. Authors obtained written permission from copyright owners for any excerpts from copyrighted works that are included and have credited the sources in the article. This research was supported by NIH/National Center for Advancing Translational Science UCLA CTSI Grant Number KL2TR000122 and National Institute on Aging Grant Number K23 AG049181-01 (JMP). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. The investigators retained full independence in the conduct of this research. OZR and BTR are married.
Author contributions
OZR, JMP, and RF contributed to study design. OZR, JMP, RF, BTR, and RS contributed to drafting the article. OZR and RF contributed to data acquisition. RF contributed to statistical analysis. OZR, RF, JMP, BTR, and RS contributed to data analysis and interpretation. OZR, JMP, RF, BTR, and RS contributed to article revisions.
Disclosure
The authors report no conflicts of interest in this work.