Medication Regimen Complexity Index (MRCI)
Also known as: MRCI
The Medication Regimen Complexity Index (MRCI) is a clinician-administered quantitative measure that objectively assesses the complexity of a patient's medication regimen based on the number of medications, frequency of dosing, and form of administration. Developed by Morgado, Rolo, and Castelo-Branco in 2012, the MRCI quantifies an important adherence barrier—the complexity of taking multiple medications with different schedules and administration routes. The MRCI is unique among adherence tools in that it measures an objective regimen characteristic (not patient behavior or belief), making it useful for deprescribing decisions, medication reconciliation, and identifying high-risk patients for non-adherence due to complexity.
Read the full method
Sign in with a free account to read this section.
Method map
The neighbourhood of related methods — select a node to explore.
When to use it
The MRCI is appropriate for any patient on multiple medications and is particularly valuable in situations where regimen simplification is a viable strategy: polypharmacy in elderly patients, medication review and deprescribing initiatives, identification of high-risk patients for non-adherence due to complexity, transition of care (e.g., hospital to home), and medication optimization in chronic disease management. The MRCI is used by pharmacy teams, care coordinators, and providers engaged in medication reconciliation and simplification. It is also valuable in research examining the relationship between regimen complexity and adherence outcomes.
Strengths & limitations
- Objective, modifiable measure: Unlike beliefs or psychological barriers, regimen complexity is an objective characteristic that can be directly simplified through deprescribing or regimen redesign.
- Clinically actionable: Identifies specific targets for intervention (e.g., 'patient is on four different medications with different frequencies; simplify to two once-daily regimens').
- Captures under-recognized barrier: Many patients struggle with adherence due to complexity alone, even when motivated; MRCI quantifies this barrier.
- Predicts poor outcomes: Research shows MRCI independently predicts non-adherence, hospitalizations, and medication errors, even controlling for disease severity and beliefs.
- Supports deprescribing and medication reconciliation: Guides prioritization of which medications to simplify, combine, or discontinue.
- Does not measure patient experience: MRCI is objective complexity, but patient-perceived burden may differ (some patients find inhalers simple, others find them intimidating).
- Assumes complexity is the main barrier: A patient may have low MRCI but still be non-adherent due to cost, beliefs, or side effects; conversely, a highly motivated patient may manage high MRCI successfully.
- Does not directly measure adherence: MRCI is a regimen characteristic, not a behavioral outcome; high MRCI predicts non-adherence risk but does not determine actual adherence.
- Limited data on optimal thresholds: Specific MRCI cutoffs for 'unacceptable complexity' or 'deprescribing indication' vary by population and are not universally established.
- Requires complete medication data: Calculation depends on accurate, comprehensive medication list; errors or omissions in the list will misrepresent complexity.
Frequently asked
How do I calculate MRCI for a patient on 'as-needed' medications?
As-needed (PRN) medications are assigned a frequency score of 2 in the MRCI algorithm, reflecting that variable dosing adds complexity and burden even though the exact number of doses is unpredictable. For example, a patient using albuterol inhaler 4 times daily as-needed gets: (4 points for inhaler form) × (2 points for as-needed frequency) = 8 MRCI points. If the patient is truly taking it only once weekly, the actual adherence burden is lower, but MRCI reflects the prescribed complexity.
Is it better to simplify a regimen or to work on patient motivation?
Both matter. Regimen simplification (reducing MRCI) removes an objective barrier and is often the easiest intervention. However, if complexity is not the main barrier (e.g., patient has high beliefs in medication necessity but is forgetful with a simple regimen), simplification alone may not improve adherence. Combine regimen optimization with patient-centered counseling addressing beliefs, motivation, and specific barriers.
Can I reduce MRCI by switching from twice-daily to once-daily dosing?
Yes, if a once-daily equivalent exists. Switching from a twice-daily immediate-release formulation to a once-daily sustained-release formulation of the same drug can substantially reduce MRCI and improve adherence. However, ensure the once-daily formulation is therapeutically equivalent and appropriate for the patient's renal function, dosing flexibility, and other medications.
How does MRCI help in deprescribing?
MRCI helps identify regimens where simplification might be possible. A patient with MRCI>15 is a candidate for medication review. Work with the patient and clinical team to identify: (1) medications not currently benefiting the patient, (2) medications that could be de-escalated (lower dose, less frequent), or (3) duplicate therapy (two medications in the same class where one is sufficient). However, deprescribing decisions must be based on clinical appropriateness, not just MRCI; do not discontinue essential medications solely to reduce complexity.
Sources
- Morgado, M., Rolo, S., & Castelo-Branco, M. (2012). Pharmacotherapy, 32(7), 652-660. (Original MRCI); Semla, T., & Beizer, J. (2018). American Geriatrics Society Beers Criteria for Potentially Inappropriate Medication Use in Older Adults. Journal of the American Geriatrics Society. link ↗
How to cite this page
ScholarGate. (2026, June 3). Medication Regimen Complexity Index (MRCI). ScholarGate. https://scholargate.app/en/pharmacology/medication-regimen-complexity
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
- Medication Adherence Rating ScalePharmacology↔ compare
- Medication Understanding and Use Self-Efficacy ScalePharmacology↔ compare
- Tablet Questionnaire for Medication AdherencePharmacology↔ compare
- Treatment Satisfaction Questionnaire for MedicationPharmacology↔ compare