Studies have consistently observed that many patients stop taking prescribed medications, thereby reducing the effectiveness of care for chronic conditions.^1-4 Investigators have associated numerous factors with discontinuation of medications; however, there are no prediction models that can accurately forecast when an individual will stop taking a prescribed medication or why.^5,6 Integrated healthcare systems such as the Veterans Health Administration (VHA) may be able to use their electronic healthcare records to screen enrolled populations and identify patients as they appear to discontinue a medication.⁷ However, mass screening programs may compel healthcare systems to follow up a large number of positive screens. Thus, false positives and identifi cation of individuals that most likely would not be amenable to restoration of medication use must be minimized.⁸

We developed and evaluated a screening program for VHA electronic health records. The primary objective was to identify patients as they stopped taking statin medications prescribed by Veterans Administration (VA) healthcare providers to reduce their cholesterol, hence the risk of adverse cardiovascular events including death. Specifi c aims were to estimate the proportions of true and false positive screens and the positive predictive value. A follow-up survey was mailed to positive screens to ascertain the reasons they stopped getting their statin prescriptions from the VHA and to help determine the percentage of positive screens that might be good candidates for remedial intervention.

METHODS

Screening Program

The screening program was developed and tested in a VA healthcare system. Similar to other VA healthcare systems, the Veterans Health Information Systems and Technology Architecture (VistA) hierarchical files contain the electronic health records for a large hospital with outpatient clinics and several regional community-based outpatient clinics. We focused on continuing use of statins because they are commonly prescribed for long-term use, and lack of persistent use has been well documented in several healthcare systems.^9-12 This evaluation and consent process was reviewed and approved by the local Committee for Human Subjects Research.

Files of VHA prescriptions (new, refill, partial fill) in VistA were screened biweekly beginning in February 2010 with 9 months of prior prescription records. Eligible individuals had received at least 2 separate 30- day supplies of a statin during the screening period to exclude dose adjustments and the impact of side effects that occur early in the course of treatment. A “past due date” was calculated as the date of release of the last statin supply plus the days of supply dispensed and any carryover from previous supplies in the fi le of statin prescriptions accumulated by the screening program. In addition, the calculated past due date was postponed by any inpatient days in the patient treatment file and a 120-day grace period. This grace period was based on past studies of medication persistence,¹³ and a separate (different data) preliminary examination of how much false positive screening rates increased as the length of the grace period was reduced from 180 to 30 days. Whenever the Minneapolis VistA records indicated a patient was past due for a statin resupply and there was no indication the recipient was deceased, VistA files maintained by other VA healthcare systems were searched to fi nd additional statin supplies, inpatient stays, and deaths. A positive screen was identifi ed whenever a patient’s calculated past-due date occurred before the screening date. Several descriptive variables were extracted from VistA files, including the type of prescriber (physician, other); whether the last supply was a new order or refill, delivered by mail, or on formulary; patient demographics; and address information.

Follow-up Survey

A 3-page survey was mailed to the first 1000 positive screens that had a valid non-institutional postal address in the patient file. An introductory letter was sent, then the survey package, including a cover letter, preaddressed, postage-paid survey return envelope, and a $5 payment. A second survey packet without money was sent if no response was received within about 2 weeks. A third packet was sent via Federal Express or United Parcel Service after another 2 weeks without a response.

The survey instructed the recipient to look at the labels on their prescription containers, and asked whether they still had any of their statin which the VHA had most recently dispensed, and whether they were still taking any of that particular statin. If they were not taking the statin, the survey asked for the reason(s) they stopped it, using a 21-item checklist and an open-ended query. The survey asked everyone if they got their statin supply from any place other than a VHA pharmacy during the past 4 months, whether others (Medicare, Medicaid or state assistance program, employer, union or retirement insurance, military) helped them pay for their medicines, if they had stayed overnight in a non-VHA hospital or traveled away from home for a week or more during the past 4 months, and whether a doctor, nurse, or pharmacist had reduced their statin dose, or if they had done so on their own.

Administrative Data

Nine months after the last survey was sent to positive screens, scrambled social security numbers of the 1000 positive screens were used to extract information from national VHA administrative records. The VA Decision Support System (DSS) Outpatient Pharmacy National Data Extract that is extracted from all VistA systems was used to determine whether each positive screen received any more supply of any statin from the VHA before their calculated past due date (a false positive screen) or did not (a true positive screen), and whether they received a VHA statin supply within 6 months after their past due date that would be consistent with a temporary gap in supply.