Question:
When coding E/M services, what drugs qualify as those requiring “intensive monitoring for toxicity” on the MDM Risk table?
Answer:
Therapeutic drug monitoring is required for a variety of reasons, one of which is a drug’s high potential for toxicity.
Intensive monitoring for toxicity is normally associated with drugs having what’s called a “narrow therapeutic range” or “narrow therapeutic index” (NTI). This means that there is a very small range between the minimum concentration of the drug needed to produce the desired therapeutic effect and the maximum concentration beyond which toxicity or death can result. The concentrations of these drugs must be intensively monitored to ensure that they are in this “sweet spot.”
There is no official US Food and Drug Administration (FDA) or government agency list of narrow therapeutic index (NTI) drugs. However, the Board of Pharmacy of some states maintain a list of what they consider to be NTI drugs, a list used to enforce policies which restrict pharmacists from substituting generic equivalents for these drugs without specific consent from the practitioner and/or patient.
Also, some payers publish lists of drugs they deem to be NTI drugs, such as Wellmark BC/BS as seen at this link: www.wellmark.com/Products/pharmacy/nti.aspx
As stated on Wellmark’s site:
Some drugs are identified as having a narrow therapeutic index (NTI) by the Food & Drug Administration (FDA). With NTI drugs, small changes in the dosage could cause toxic results.
Patients taking NTI drugs require constant monitoring so that the level of medication can be adjusted to assure uniform and safe results. Members will not be required to pay the difference in cost between brand and generic for drugs that are classified as NTI medications.
NTI drugs are identified in the Wellmark Drug List.
For coders, I recommend using an NTI drug list from a state pharmacy board or specific payer if possible, as a starting point for determining which drugs fall into the “drugs that require intensive monitoring for toxicity” category, and add any other drugs that physicians inform you also need this intensive monitoring along with the reason these physicians feel this drug qualifies for this status.