Primary Care Coding Alert

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


Virginia 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 probably reject the ICD-9 code as incomplete.

Assign the fourth digit based on the asthma category:

493.0x (Extrinsic asthma ), 493.1x (Intrinsic asthma), 493.2x (Chronic obstructive asthma), 493.8x (Other forms of asthma), and 493.9x (Asthma, unspecified).

Then, for 493.0-493.2 and 493.9, 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 2 for patients with asthma that is now exacerbated (in other words, something has caused the condition to flare up). For 493.8, the fifth digit is either 1, which indicates -Exercise-induced bronchospasm,- or 2, -which indicates -Cough-variant asthma.-

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

Example: An extrinsic asthma patient 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]).

Link 94640 to 493.02. Reporting 2 as the fifth digit shows 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 coded treatment unnecessary.