, Volume 25, Issue 4, pp 284-290

Primary Medication Non-Adherence: Analysis of 195,930 Electronic Prescriptions

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ABSTRACT

BACKGROUND

Non-adherence to essential medications represents an important public health problem. Little is known about the frequency with which patients fail to fill prescriptions when new medications are started (“primary non-adherence”) or predictors of failure to fill.

OBJECTIVE

Evaluate primary non-adherence in community-based practices and identify predictors of non-adherence.

PARTICIPANTS

75,589 patients treated by 1,217 prescribers in the first year of a community-based e-prescribing initiative.

DESIGN

We compiled all e-prescriptions written over a 12-month period and used filled claims to identify filled prescriptions. We calculated primary adherence and non-adherence rates for all e-prescriptions and for new medication starts and compared the rates across patient and medication characteristics. Using multivariable regressions analyses, we examined which characteristics were associated with non-adherence.

MAIN MEASURES

Primary medication non-adherence.

KEY RESULTS

Of 195,930 e-prescriptions, 151,837 (78%) were filled. Of 82,245 e-prescriptions for new medications, 58,984 (72%) were filled. Primary adherence rates were higher for prescriptions written by primary care specialists, especially pediatricians (84%). Patients aged 18 and younger filled prescriptions at the highest rate (87%). In multivariate analyses, medication class was the strongest predictor of adherence, and non-adherence was common for newly prescribed medications treating chronic conditions such as hypertension (28.4%), hyperlipidemia (28.2%), and diabetes (31.4%).

CONCLUSIONS

Many e-prescriptions were not filled. Previous studies of medication non-adherence failed to capture these prescriptions. Efforts to increase primary adherence could dramatically improve the effectiveness of medication therapy. Interventions that target specific medication classes may be most effective.

Preliminary versions of this research were presented at the Society of General Internal Medicine Annual Meeting, Pittsburgh, PA, April, 10, 2008, and the International Conference on Pharmacoepidemiology, Copenhagen, Denmark, August 18, 2008.