TABLE 4.

Considerations for designing and validating studies using administrative pharmacy records to identify active medication at a fixed time point

Comparison group for validation studies	Is the proposed study design prospective or retrospective? If prospective options include: Biochemical markers Patient interview Patient survey Medication reconciliation (patient interview guided by clinician and based upon existing medical record medication list) If retrospective options include: Biochemical markers (may be retrospectively collected if ordered as part of routine clinical care) Electronic medical record Patient survey (if part of routine clinical care, such as patient intake during a clinic visit) Medication reconciliation (may be retrospective if completed as part of routine clinical care such as during new patient visits or hospital admission)
Timeframe	What will the primary method for identifying active medications? (Figure 2) Use of fixed look-back period approaches requires a decision on how far before the index date a medication can be filled to be counted as active. Longer look-back periods may classify medications no longer in use as active while shorter look-back periods may miss medications filled intermittently or with extended supplies. Use of medication-on-hand approaches may be limited for medications without a recorded day supplied, medications with nonstandard dosage forms, and those used intermittently If a fixed look-back period approach is used, will multiple preindex date fills be required or minimum days’ supply? If a medication-on-hand approach is used, will a grace period be included to account imperfect adherence or refill delays? Will postindex date fills be considered?
Scope of medications	Are nonprescription medications, supplements, and vitamins important to the research question? Does the pharmacy database record fills of nonprescription medications, supplements, or vitamins? Will a different approach be used for examining as-needed medications which may not be filled at regular intervals? Will a different approach be used for examining medications used for a short duration (eg, antibiotics) which may not be filled at regular intervals? Will a different approach be used to examine medications with nonstandard dosage forms (eg, topical/inhaled/injection medications) for which days' supply may not be readily measurable?
Medication sources	Is the pharmacy database being used likely to include all medications being taken by the study population? Is the patient likely to obtain prescriptions from another source not captured by the database? Prescriptions filled with cash, no-charge, and drug coupons may not be recorded in many pharmacy databases. Recent hospitalization, residence in a skilled nursing facility, and incarceration may result in medication provided by alternative pharmacy sources or not captured in claims data.
Multiple measures	Would study findings be strengthened by comparing multiple approaches for establishing patients' active medication list?