3.3 Adherence Definitions in Medication History

Adherence Definitions in Medication History

Quick Answer: Adherence is taking medication as agreed. Nonadherence is not following that plan. Persistence is continuing therapy over time. Intentional nonadherence is a conscious choice; unintentional nonadherence is usually a barrier like forgetting or access problems.

Before you calculate Proportion of Days Covered (PDC) in later chapters, you must speak the language of adherence during history taking. Claims data show whether fills happened. The patient interview explains why. MTM technicians who only say "noncompliant" miss the actionable detail pharmacists need for a Medication Therapy Review (MTR), Targeted Medication Review (TMR), or adherence outreach.

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Core Terms

Adherence

Adherence (preferred modern term; older materials may say "compliance") means the extent to which a patient's medication-taking behavior matches the agreed regimen: right drug, dose, route, frequency, and timing. In history collection, ask behaviorally:

• "In the past week, how many doses of your blood pressure pill did you miss?"
• "Do you usually take it in the morning, or does the time change day to day?"

Avoid blaming language. "Help me understand how this fits your day" yields better data than "Why aren't you compliant?"

Nonadherence

Nonadherence is any clinically meaningful departure from the agreed plan—missed doses, wrong timing, self-directed dose changes, early stops, or never starting a prescribed medicine (primary nonadherence when the prescription is never picked up).

Nonadherence is a finding, not a character judgment. Document patterns: late refills, partial fills, "I cut the tablet in half to save money," or "I only take it when I feel bad."

Persistence

Persistence describes the duration of continuous therapy from initiation until the patient discontinues. A patient can be persistent for six months (still on therapy) yet poorly adherent day to day (misses many doses). Another patient may be highly adherent while on therapy but not persistent because they stopped after two months.

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Intentional vs Unintentional Nonadherence

This distinction drives the intervention type.

Intentional nonadherence

The patient chooses not to take the medicine as prescribed. Common drivers:

• Cost or coverage ("I can't afford the copay")
• Side effects or fear of side effects
• Belief the medicine is unnecessary ("My pressure feels fine")
• Distrust of the medication or healthcare system
• Complexity fatigue / preference to take fewer pills

Intentional nonadherence responds better to motivational interviewing, cost alternatives, shared decision-making, and addressing beliefs—not to a louder reminder app alone.

Unintentional nonadherence

The patient wants to follow the plan but barriers get in the way:

• Forgetting doses
• Misunderstanding instructions ("I thought twice a day meant two at breakfast")
• Complex regimens (many times of day)
• Physical barriers (cannot open bottles, swallowing difficulty)
• Transportation or pharmacy access problems
• Running out between fills / delayed mail-order

Unintentional nonadherence often improves with synchronization, blister packs, simpler schedules, alarms, caregiver support, or 90-day supplies—after the pharmacist confirms clinical appropriateness.

Many patients show mixed patterns. Document both: "Forgets evening dose; also skips when money is tight at month-end."

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How These Terms Appear in MTM History Work

During medication history for a CMR or TMR preparation:

1. Compare refill claims or bottle dates with patient report.
2. Ask open questions about missed doses without accusing.
3. Classify barriers as intentional, unintentional, or mixed.
4. Flag adherence-related medication-related problems for the pharmacist.
5. Leave PDC math and clinical regimen changes to the appropriate workflow (pharmacist decision; calculation skills appear in Domain 2).

Technician Script — Separating "Won't" from "Can't"

Tech: "Your metformin refill looks about two weeks late most months. What usually gets in the way?" Patient: "Honestly, the stomach upset is annoying, so I skip doses when I have a busy workday." Tech: "Thanks for being honest—that helps. I'll note intentional skipped doses because of stomach upset on busy days. The pharmacist can talk through options like taking it with food, dose timing, or whether another approach fits better."

Contrast with unintentional:

Patient: "I mean to take it. I just blank on the night pills after I fall asleep on the couch." Tech: "That sounds like forgetting the evening dose—not that you're choosing to stop. I'll document unintentional missed evening doses and ask the pharmacist about simplifying your schedule or reminder tools."

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Words to Avoid—and Better Replacements

Internally, "nonadherence" remains a precise chart term. Externally, collaborative language improves disclosure—the raw material of a good medication history.

Remember: persistence ≠ adherence. A patient still "on" a statin for a year (persistent) who takes it four days a week (low adherence) remains a high-priority MTM candidate, especially for Star Ratings measures discussed later. Your history notes should make that distinction visible to the pharmacist.