Medication Discrepancy Codes: Code A vs. Code B
Code A (omission) means a medication the patient IS currently taking is MISSING from the medical record, while Code B (commission) means a medication the patient is NO LONGER taking is still PRESENT on the medical record. 1
Understanding the Key Distinction
The fundamental difference lies in the direction of the error:
Code A (Omission): The medical record is incomplete - it fails to document an active medication the patient is actually taking. This is also termed "not in record" in medication reconciliation terminology. 1
Code B (Commission): The medical record is outdated - it incorrectly lists a medication that the patient has discontinued. This is also termed "no longer taking" or "medication no longer taken" in the literature. 1
Clinical Risks Associated with Each Code Type
Code A (Omission) Risks:
- Failure to receive necessary medication when the undocumented drug is not continued during care transitions 1
- Adverse drug events from drug-drug interactions that go unrecognized because the medication isn't in the record 1
- Wrong medication prescribed because the clinician is unaware of what the patient is already taking 1
Code B (Commission) Risks:
- Medication overdose from continuing a drug that should have been stopped 1
- Adverse drug events from unnecessary polypharmacy 1
- Over-dosage when medications are inappropriately continued 1
Prevalence and Clinical Significance
Both discrepancy types are among the most common medication errors identified during reconciliation, with studies showing that 2-3 medication discrepancies are found on average each time a patient undergoes medication reconciliation. 1 Approximately 4-6% of these discrepancies are clinically significant and place patients at risk for harm. 1
Common Pitfall to Avoid
The terminology can be confusing because "omission" might intuitively suggest something the patient is NOT taking, but it actually refers to something OMITTED from the record that the patient IS taking. Similarly, "commission" might suggest an active medication, but it refers to a medication erroneously COMMITTED to the record despite discontinuation. 1