The Validity of Self-Reported Primary Adherence Among Medicaid Patients Discharged From the Emergency Department With a Prescription Medication - 20/08/13

Doi : 10.1016/j.annemergmed.2013.01.026

Ru Ding, MS ^a, Scott L. Zeger, PhD ^c, Donald M. Steinwachs, PhD ^d, Melinda J. Ortmann, PharmD ^e, Melissa L. McCarthy, ScD ^a,^b,^⁎
^a Department of Health Policy, George Washington University, Washington, DC
^b Department of Emergency Medicine, George Washington University, Washington, DC
^c Department of Biostatistics, Johns Hopkins University, Baltimore, MD
^d Department of Health Policy and Management, Johns Hopkins University, Baltimore, MD
^e Department of Pharmacology, Johns Hopkins University, Baltimore, MD

Address for correspondence: Melissa L. McCarthy, ScD

Résumé

Study objective

We determine the validity of self-reported prescription filling among emergency department (ED) patients.

Methods

We analyzed a subgroup of 1,026 patients enrolled in a randomized controlled trial who were prescribed at least 1 medication at ED discharge, were covered by Medicaid insurance, and completed a telephone interview 1 week after the index ED visit. We extracted all pharmacy and health care use claims information from a state Medicaid database for all subjects within 30 days of their index ED visit. We used the pharmacy claims as the criterion standard and evaluated the accuracy of self-reported prescription filling obtained during the follow-up interview by estimating its sensitivity, specificity, positive likelihood ratio and negative likelihood ratio tests. We also examined whether the accuracy of self-reported prescription filling varied significantly by patient and clinical characteristics.

Results

Of the 1,635 medications prescribed, 74% were filled according to the pharmacy claims. Subjects reported filling 90% of prescriptions for a difference of 16% (95% confidence interval [CI] 14% to 18%). The self-reported data had high sensitivity (0.96; 95% CI 0.95 to 0.97) but low specificity (0.30; 95% CI 0.26 to 0.34). The positive likelihood ratio (1.37; 95% CI 1.29 to 2.46) and negative likelihood ratio (0.13; 95% CI 0.09 to 0.17) tests indicate that self-reported data are not a good indicator of prescription filling but are a moderately good indicator of nonfulfillment. Several factors were significantly associated with lower sensitivity (drug class and over-the-counter medications) and specificity (drug class, as needed, site and previous ED use).

Conclusion

Self-reported prescription filling is overestimated and associated with few factors.

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Plan

Introduction

Materials and Methods

Setting and Selection of Participants

Methods of Measurement

Primary Data Analysis

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	Supervising editor: Donald M. Yealy, MD
	Author contributions: All authors conceived the study and contributed substantially to the article's revision. MLM obtained research funding. RD and MLM supervised the data collection and interfaced with the Medicaid staff; managed the data, including quality control; drafted the article; had full access to all of the data in the study; and take responsibility for the integrity of the data and the accuracy of the data analysis. RD and SLZ provided statistical advice on analysis of the data. MLM takes responsibility for the paper as a whole.
	Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. This study was supported by award 1RC1LM010424-01 from the National Library of Medicine and award K01HS017957 from the Agency for Healthcare Research and Quality. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Library of Medicine, the National Institutes of Health, or the Agency for Healthcare Research and Quality. The sponsors were not involved in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the article.
	Please see page 226 for the Editor's Capsule Summary of this article.
	Publication date: Available online March 15, 2013.