Best Possible Medication History (BPMH)

A BPMH is fundamentally defined by the systematic triangulation of information from at least two independent sources. This process moves beyond a simple patient interview to create a high-reliability record.

• Primary Sources: Patient/caregiver interview, inspection of medication vials or blister packs, and review of the patient's own medication list.
• Secondary Sources: Community pharmacy dispensing records, insurance claims data, previous hospital discharge summaries, and nursing home transfer records.
• Discrepancy Resolution: When sources conflict, the pharmacist must use clinical judgment to determine the most accurate regimen, documenting the rationale for the final decision.

The BPMH interview is a standardized, systematic conversation, not an informal chat. It employs a brown-bag review and open-ended questioning to uncover non-prescription items and actual usage patterns.

• Show-and-Tell: Patients are asked to physically present all medications, including inhalers, patches, drops, and over-the-counter drugs.
• Probing Questions: The interviewer explicitly asks about adherence ('How many doses did you miss last week?'), recent changes, and medications prescribed by specialists.
• Non-Verbal Cues: The process accounts for health literacy barriers by using visual aids and pill identification guides to confirm what the patient is actually taking.

A true BPMH captures the complete pharmacotherapeutic picture, extending far beyond prescription pills to include all substances that could cause an adverse event or interaction.

• Prescription Medications: All regularly scheduled and PRN (as needed) drugs.
• Non-Prescription Items: Over-the-counter drugs, vitamins, herbal supplements, and traditional medicines.
• Dose & Frequency: The exact strength, route of administration, and the actual dosing schedule the patient follows, which may differ from the label.
• Temporal Context: The date the medication was last taken and the duration of therapy are critical for preventing withdrawal syndromes or duplicate loading doses.

The output of a BPMH is a structured, coded, and attributable record, not a free-text narrative. This standardization is essential for interoperability and downstream clinical decision support.

• Coded Data: Medications are mapped to standardized terminologies like RxNorm to enable automated drug-drug interaction and allergy checking.
• Source Attribution: Each medication entry is explicitly linked to its source of information (e.g., 'per patient vial' or 'per CVS dispensing record') to establish data provenance.
• Discrepancy Flagging: The BPMH serves as the baseline against which admission orders are compared, with any unintentional discrepancies clearly documented and communicated to the prescriber.

The gold standard for BPMH collection is execution by a trained clinical pharmacist or a certified pharmacy technician under pharmacist supervision. This leverages specialized expertise in medication management.

• Clinical Inference: Pharmacists can resolve incomplete histories by inferring a missing dose based on a patient's reported frequency and the standard available strengths.
• Therapeutic Duplication: A pharmacist is uniquely trained to identify a patient taking both a brand-name and generic version of the same drug, a common error missed by non-clinicians.
• Cognitive Dissonance: The process requires navigating the patient's belief about what they take versus the objective evidence, a reconciliation skill central to pharmacy practice.

The BPMH is not an end in itself; it is the definitive pre-admission baseline against which all subsequent medication orders are compared during the formal Medication Reconciliation (MedRec) process.

• Comparator Role: Every admission, transfer, and discharge order is compared line-by-line to the BPMH to identify unintentional discrepancies.
• Error Prevention: This comparison catches high-risk omission errors (failing to restart a critical beta-blocker) and commission errors (prescribing a drug the patient is allergic to).
• Continuity of Care: The BPMH travels with the patient across transitions, ensuring that the verified home regimen is communicated to the next provider of care.