Pediatric Coding Alert

Question: I always thought you billed Z79.899 whenever a patient was taking a long-term medication that does not have a more specific code, such as insulin, warfarin, metformin, and so on. However, I remember seeing somewhere that you don’t bill for meds associated with conditions where it is assumed most patients are on some type of medication. So, how do I use this code?

AAPC Forum Participant

Answer: Use of Z79.899 (Other long term (current) drug therapy) is subject to three ICD-10 guidelines that instruct you on its proper use.

The first two — 1.C.4.a.3 and 1.C.6.a — provide instructions for use of the code in cases of long-term drug use for patients with diabetes and secondary diabetes. They tell you to use the code if the patient is using “an injectable non-insulin antidiabetic drug” such as Trulicity or Victoza and any other injectable GLP-1 receptor agonist, in addition to insulin, coded with Z79.4 (Long term (current) use of insulin), or oral diabetes drugs, such as metformin, coded to Z79.84 (Long term (current) use of oral hypoglycemic drugs).

So, as ICD-10 does not assign a specific Z79 code to injectable non-insulin antidiabetic drugs, it would be correct to assign Z79.899 to them to document their current, long-term use. By extension, it also seems clear that ICD-10 tells you to use Z79.899 if the drug use is not more accurately reported with a specific code from the Z79 codes. But before you assign any of these codes, you need to know what type of drug use should be coded.

The third guideline —1.C.21.c — provides guidance for this. It tells you that the codes are not for “patients who have addictions to drugs” and not for “use of medications for detoxification or maintenance programs to prevent withdrawal symptoms” (emphasis added). In such cases, the guideline instructs you to “assign the appropriate code for the drug use, abuse, or dependence instead.” So, per this guideline, we can assume that you should report long-term drug use other than in cases of addiction, or for conditions such as detoxification or drug withdrawal, with a Z79 code.

The same guideline also tells you that you should use the codes “if the patient is receiving a medication for an extended period as a prophylactic measure … or as treatment of a chronic condition … or a disease requiring a lengthy course of treatment (such as cancer).” You should not assign one of the Z79 codes “for medication being administered for a brief period of time to treat an acute illness or injury.” The guideline does not define “extended period” with a particular timeframe, so you should look to the patient’s condition and consult with your pediatrician before assigning a code from the group.

And remember: You should only use a Z79 code if the patient is taking the medication at the time of an encounter (in other words, the drug use is “current”).