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Coding in MedDRA and some situations

MedDRA coding is carried out with the help of MedDRA browser. Most of the adverse reaction databases facilitate uploading of the MedDRA dictionary within the database itself. Coder types the reported term which can be a diagnosis or symptom or sign or investigation. If there is a direct match of the LLT, this is picked automatically. For instance where a direct match is not available, a list of suggested / similar terms populates and coder has to manually choose the code that is closest to the reported term.

General principles of term selection:

  • Find a term as close to the verbatim as possible. One should code only the reported term without interpreting or drawing information from other sources
  • Code only verbatim reported in English, other language verbatim should be coded post translation of the non-English report into English report
  • Do not classify a verbatim term in a way that would change, add, or subtract from its original meaning or content
  • When the most specific term for the verbatim is not available, use medical judgement to choose a clinically equivalent term or a general term that does not misinterpret the verbatim
  • When considering selecting an LLT, check the hierarchy above the LLT (PT level and further up the hierarchy to HLT, HLGT and SOC) to ensure the placement accurately reflects the meaning of the reported term.
  • The predefined term hierarchy should not be altered by making ad hoc structural alterations, including changing the primary SOC allocation. This would compromise the integrity of MedDRA.
  • If necessary, a change request can be sent to the MSSO (Maintenance and Support Services Organisation) Dictionary Services group or MedDRA change requests are initiated by client when an appropriate term is not available for coding or the hierarchy available does not seem to represent the verbatim accurately

Common problems faced by medical coding expert while coding:

Appropriate coding requires clear initial data. What is clear to the investigator at the time of reporting may turn out to be a nightmare for the coder and the medical expert. There are issues like

  • illegible verbatim term
  • spelling errors
  • use of abbreviations
  • multiple signs and symptoms which may lead to some diagnosis, recorded as separate events (for example: signs and symptoms recorded as abdominal pain, increase in serum amylase and lipase but not specified as pancreatitis)
  • multiple medical concepts recorded together. To code we need to split the terms.
  • event is recorded without mentioning the site e.g. ulcer is recorded without additional information like moth ulcer, leg ulcer etc

Some verbatim make you smile but are in fact coding challenges. A few are listed in the MedDRA guide

  • Went to hell
  • Recurrent fatal stroke
  • Died of cancer of the placebo
  • Barely visible posterior
  • Can’t control patient during menses
  • Normally normal after drinking coffee
  • His nodule is sticking out

Some specific coding situations: Misuse, abuse, addictions

These concepts are closely related and challenging to interpret. The medical reviewer should look at the circumstances (who misused? with what intention? in what dose?) of each case before choosing the correct LLT and PT. Let us view some situations.

A patient intentionally using a drug without prescription for an indication, even if it is in therapeutic dose, is misuse.

  • Patient knowingly consumed the medication twice daily instead of once
  • The LLT will be Intentional misuse in dosing frequency

A patient/consumer consuming drug in higher than therapeutic dose for purpose other than therapeutic is abuse.

  • Patient occasionally used morphine to feel the euphoria
  • The LLT will be opiod abuse, episodic use. Note how both concepts of the verbatim are captured

Use of anabolics by athletes

  • LLT will be steroid abuse

Patient/ consumer abusing repeatedly and being dependant on it is addiction.

  • Patient became dependant on alcohol
  • LLT will be dependence on alcohol

A patient or doctor administering a wrong medication in therapeutic dose unintentionally, is medication error.

  • Patient was administered wrong drug and experienced hypotension
  • LLT will be Wrong drug administered, Hypotension; notice how both concepts are captured

Many companies have their own internal guidelines for coding. Here misuse and medication error often overlap. eg sometimes, cases coding to any of the following preferred terms are identified as drug misuse cases.

  • Labelled drug-drug interaction medication error
  • Labelled drug-food interaction medication error
  • Labelled drug-disease interaction medication error
  • Documented hypersensitivity to administered product
  • Wrong drug administered
  • Underdose
  • Incorrect dose administered
  • Drug dose omission
  • Drug administration error
  • Incorrect dose administered
  • Incorrect dosage form administered
  • Incorrect drug administration rate
  • Incorrect duration of administration
  • Drug prescribing error
  • Drug dispensing error

For drug prescribing error and drug dispensing error, collectively called a medication error, there are some interesting situations. These errors may or may not result in adverse effects, or adverse effects may have been prevented. Let us look at a few

Medication error with consequences

Capture the reason for error as well as the consequence.

Patient administered wrong drug and suffered hypotension

  • LLT will be wrong drug administered, hypotension

Wrong drug dispensed because of similar sounding drug names. Patient consumed it and experienced gastritis

  • LLT will be drug name sound alike, wrong drug dispensed, wrong drug administered, gastritis

Insulin was injected with a wrong syringe, resulting in higher dose being administered and consequent hypoglycaemia

  • LLT will be drug administered in wrong device, accidental overdose, hypoglycaemia

Medication error without consequences

Since there has been no adverse event none has to be reported, but it is important to record/code that an error could have potentially occurred

There are also some situations where a medication error has occurred but the drug was not consumed or administered. This is an intercepted medication error.

In such cases one could only select a term to describe the medication error or may additionally add an LLT of no adverse effect.

Medication given IV instead of IM, but patient did not suffer from any adverse effects.

  • LLT will be IM formulation administered by other route, no adverse effect

Pharmacist notices that drug names look alike and is concerned about the possibility of some adverse events.

This is a potential situation; drug has not been administered. Yet recording this potential medication error, along with the cause is important

  • LLT will be Drug name look alike, circumstance or information capable of leading to medication error

Physician prescribed a wrong dose of drug but pharmacist noticed it and did not dispense

  • LLT will be intercepted drug prescribing error

Pharmacist dispensed a wrong drug but patient noticed it and did not consume it

  • LLT will be intercepted drug dispensing error

Please note that the errors are kept at the feet of the responsible parties

In future releases let us look at a few more coding situations


  1. Deven Babre. Medical coding in clinical trials. Perspectives in Clinical research 2010;1:29
  2. MedDRA term selection: Points to consider.ICH-Endorsed Guide for MedDRA users. Release 4.21, March 2021
Dr. Vishwas Sovani (January 2022)


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