Part B Insider (Multispecialty) Coding Alert

Hint: Know the definitions of intrinsic and extrinsic before you select your ICD-9 code.

Question: What is the ICD-9 code that we should report when a patient presents with mild, intermittent asthma? We have been unable to find it in the ICD-9-CM manual and our carrier could not lead us to an appropriate code either.

Answer: The ICD-9 manual does not include a specific code for mild, intermittent asthma. Rather, asthma is broadly classified under 493.x with several subclassifications, including the following, among others:

• 493.0x -- Extrinsic asthma

• 493.1x -- Intrinsic asthma

• 493.2x -- Chronic obstructive asthma

• 493.8x -- Other forms of specified asthma

• 493.9x -- Asthma, unspecified.

Codes 493.0x and 493.1x imply the existence of specific etiologies (causes) for the asthma.

For example: Extrinsic asthma is commonly due to allergic reactions and often occurs in children, whereas intrinsic asthma commonly occurs in adults due to reasons other than allergies (for instance, respiratory infections, chemical inhalation, smoke inhalation, etc.).

The definition for code 493.2x implies a prolonged duration of the disease, and 493.8x classifies the remaining types of asthma that are specified, meaning exercised-induced (493.81) and cough variants (493.82).

Finally, 493.9x is for cases of asthma that are unspecified.

For the diagnosis of mild, intermittent asthma, most coding experts would consider this to be unspecified, as one cannot discern the etiology nor the duration of the disease from the diagnosis alone.

In this particular instance, unless your physician's documentation offers details that haven't been shared here, you would therefore use this code: 493.92 (Asthma, unspecified; with [acute] exacerbation).