Pulmonology Coding Alert

Question: When reporting an asthma diagnosis, do I need a fifth digit?


North Carolina Subscriber
Answer: Yes. ICD-9 requires you to use a fifth-digit subclassification with asthma codes (493.xx). If you submit four digits for an asthma diagnosis, payers will reject the ICD-9 code as truncated or incomplete.

Correct method: Assign the fourth digit based on the asthma category:

• 493.0x--Extrinsic asthma
• 493.1x--Intrinsic asthma
• 493.2x--Chronic obstructive asthma
• 493.9x--Asthma, unspecified. Then, identify the asthma's current state with the appropriate fifth digit:

• 0--... unspecified
• 1--... with status asthmaticus
• 2--... with (acute) exacerbation. For patients who do not have status asthmaticus or acute exacerbation, use a fifth digit of "0." Code 493.x0 is appropriate when the patient presents for a checkup and his asthma is controlled.

A final digit of "1" indicates that the patient has status asthmaticus, which is a medical emergency and is usually treated in the emergency department.

You should assign a "2" for patients who present with asthma that is now exacerbated (in other words, something has caused the condition to flare up).

Why it matters: Without this higher level of specificity, the payer may deny your claim for lack of medical necessity.

Example: A patient with extrinsic asthma has an acute exacerbation that requires a nebulizer treatment (94640, Pressurized or nonpressurized inhalation treatment for acute airway obstruction or for sputum induction for diagnostic purposes [e.g., with an aerosol generator, nebulizer, metered dose inhaler or intermittent positive pressure breathing (IPPB) device]). In this case, you should link 94640 to 493.02. Reporting a "2" as the fifth digit helps the payer to understand why the patient needs the treatment.

Without the final digit (or a fifth-digit subclassification of "0"), the payer may assume that the patient's asthma is under control, making the treatment you coded for unnecessary.