Coding Substance Use, Abuse, and Dependence: ICD-9 and ICD-10 Differences – Part 1

The Mental, Behavioral and Neurodevelopmental Disorders chapter of ICD underwent some significant changes for ICD-10-CM. One of the most notable changes was how documentation of substance use, abuse, or dependence and any associated mental or behavioral disorders are coded. The changes implemented provide coding choices for circumstances not previously reportable and greater specificity for existing coding options.

This Part 1 of a 3-part series will highlight the major changes and how the ICD-10 coding practices differ from those in ICD-9. Part 1 will focus on guidelines and hierarchies.

Guidelines Added for Chapter 5
In the Chapter Specific Coding Guidelines for ICD-9, under the heading of Chapter 5: Medical Disorders, one finds only the notation “Reserved for future guideline expansion.”  ICD-10 now puts that space to use as it contains 4 guidelines the provide direction when assigning codes from this chapter.

New guidelines include 5.b.1, which establishes the documentation criteria required for the selection of codes that report the current state of the patient’s condition as “in remission” when assigning codes from categories (F10-F19).

Additionally, guideline 5.b.2 outlines the criteria for code selection when provider documentation refers to use, abuse, and dependence of the same substance (e.g., tobacco, alcohol, cannabis, etc.).  In these cases, only one code should be assigned to identify the pattern of use. Determination of the correct code to report is based upon a hierarchical scale.

A hierarchy is a system of organization in which items are ranked one above the other according to status. Hierarchies are not new when it comes to coding. Codes in both the ICD-9-CM and ICD-10-CM code sets are arranged in hierarchies where codes in the same category are ranked one above another in ascending numerical order based on specificity or severity.

In ICD-10, when provider documentation refers to any combination of use, abuse, and dependence in relation to a patient’s pattern of use of the same psychoactive substances (e.g., tobacco, alcohol, cannabis, etc.), a hierarchical progression is followed in order to determine correct code assignment.
The hierarchical scale is modeled below.

As you can see from the model, dependence is at the top of the hierarchy. Below dependence in status is abuse. Use is at the bottom of the scale. This is due in part to the unspecified nature of the term “use” in this chapter of ICD-10.

The term “use” provides a mechanism for code assignment when provider documentation indicates a patient’s use of a substance but does not further specify the usage as abuse or dependence. The term “use” is found at the bottom of the scale because it does not represent a definable measure of severity. Without being able to measure the severity represented by this term it is difficult, if not impossible, to make a comparison between the status of “use” and the status of abuse or dependence and thus determine its rank in the hierarchy.

ICD-9 vs. ICD-10
ICD-9 codes for abuse of or dependence on the same substance are found in different code categories.  For example, codes for opioid dependence are found in category 304 (Drug Dependence) and codes for opioid abuse are found in category 305 (Non-dependent Abuse of Drugs).

In ICD-10, codes for use and/or abuse and/or dependence of the same substance are found within the same code category. For example, code category F11; here opioid related disorders is divided into 3 subcategories: F11.1 opioid abuse, F11.2 opioid dependence, and F11.9 opioid use.

Confusion can occur when there is conflicting documentation in the same medical record and a choice must be made between varying codes in the same code category. Guideline 5.2.b provides the direction needed in these situations by outlining the action to be taken with the hierarchy it provides. In addition, the excludes 1 notes found under various subcategories are consistent with the hierarchical organization outlined by guideline 5.b.2 as code assignment from each subcategory precludes assignment of a code from any of the other subdivisions within the same category for the same patient encounter.

This sums up the differences between the guidelines and hierarchies in ICD-9 and ICD-10 pertaining to substance use, abuse, and dependence. Check back for parts 2 and 3 when we’ll address the differences between the codes available in ICD-9 and ICD-10 for reporting use, abuse, and dependence and combination codes.

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