Tuesday, March 24, 2020

Adverse Effects, Poisonings, Underdosings, and Toxic Effects

This installment of “In the kNOW” will examine the differences in and coding of adverse effects, poisonings, underdosings, and toxic effects.  Let’s begin with a look at adverse effects.  These are conditions that a patient may develop as a result of taking a prescribed medication exactly as directed.  Another term for this would be side effects.   For example, a patient takes Lisinopril and develops angioedema of the tongue.  The appropriate code assignment and sequencing would be:

T78.3XXA  angioneurotic edema, initial

T46.4X5A  adverse effect of angiotensin-converting-enzyme inhibitors, initial

Proper code sequencing is to code first the nature of the adverse effect (angioedema, in this instance) and then the code to identify the drug.  

Poisonings can occur through a variety of different mechanisms such as:

Drug prescription or administration error
Intentional overdose
Nonprescribed drug taken with a properly prescribed and administered drug
Drug and alcohol interaction

In the circumstance of a poisoning, the appropriate poisoning code is sequenced first followed by any manifestations present.  Poisoning codes include the intent (accidental, intentional, self-harm, assault, and undetermined).  The “undetermined” intent should seldom be assigned as it is only to be used if the documentation has specified that the intent cannot be determined.  In instances where the intent is not known or is unspecified, coding professionals are directed to assign an “accidental” intent. 

An example of a poisoning would be a patient who took their prescribed Gabapentin as directed, but also had several glasses of wine, ending up in a coma.  The correct code assignment and sequencing would be:

T42.6X1A  Poisoning by other antiepileptic or sedative-hypnotic drugs, accidental, initial
T51.0X1A  Toxic effect of ethanol, accidental, initial
R40.20       Unspecified coma

In this scenario, there were two different drugs (Gabapentin and alcohol) which were responsible for the poisoning so both were coded.  Assign as many codes as necessary to capture all the drugs, medicinals, or biological substances that are documented.  When more than one code is necessary, assign separate codes, unless the Table of Drugs and Chemicals supplies a combination code.  Remember, that when drugs and alcohol are mixed, the condition is considered a poisoning.
Should a patient have substance abuse or dependence related to the reason for the poisoning, an additional code should be assigned for that abuse or dependence.  If, in our scenario above, the patient was also dependent on alcohol, then we would assign a fourth code of F10.20 for alcohol dependence. 

Underdosing is a relatively new concept in ICD-10-CM and addresses taking less of a medication than prescribed.  Last year, a change to the Official Coding Guidelines, clarified that the definition of underdosing also includes any discontinuation of a prescribed medication without provider instruction.

When coding for underdosings, it is important to remember that the underdosing code itself cannot be the principal or first-listed code.  Coding professionals will also want to assign the appropriate noncompliance codes to identify intent. 

In this scenario, a patient stops taking their Protonix after six months because they are feeling better.  Within a week, they develop severe nausea and go to see their physician, who restarts the medication.

The code and sequencing assignment would be:

R11.0           Nausea
T47.1X6A  Underdosing of other antacids and anti-gastric-secretion drugs, initial
Z91.128     Patient’s intentional underdosing of medication regimen for other reason

Harmful substances that are ingested or come into contact with a person are considered toxic effects.  Just like with poisonings, the codes include the intent associated with the toxic effect, be it accidental, intentional, self-harm, assault, or undetermined. 

A toxic effect scenario would be a person who was intentionally doused with bleach on the left forearm resulting in a first degree burn.

The correct sequencing and code assignment are:

T54.93XA  Toxic effect of unspecified corrosive substance, assault, initial
T22.512A  Corrosion of first degree left forearm, initial

A word of caution, always check the Tabular List for codes related to drugs and chemicals.  Do not rely solely on the Table of Drugs and Chemicals for code assignment. 

A final point regarding these conditions regards the use of the appropriate seventh character.  These seventh characters will indicate the phase of treatment; A for initial encounter (active treatment), D for subsequent encounter (healing phase of treatment), or S for sequela (late effect of initial condition).

Now you are In the kNOW!!

About the Author 

Dianna Foley, RHIA, CHPS, CCS  is OHIMA's Coding Education Coordinator. Dianna has been an HIM professional for 20 years. She progressed through the ranks of coder, department supervisor, and department director, to her current role as a coding consultant. 

She recently served as the program director for Medical Coding and HIT at Eastern Gateway Community College. Dianna earned her bachelor's degree from the University of Cincinnati subsequently achieving her RHIA, CHPS, and CCS certifications. She is an AHIMA Approved ICD-10-CM/PCS Trainer and a a presenter at regional HIM meetings and the OHIMA Annual Meeting.

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