Radiology Coding Alert

Question: How do I distinguish between mild, moderate, and severe persistent asthma diagnoses? What does the provider need to document in order to reach one of these diagnoses?

Oregon Subscriber

Answer: Despite the fact that physicians can report asthma of various degrees of chronicity and severity, coders more often than not have to resort to J45.909 (Unspecified asthma, uncomplicated) simply due to a lack of documentation. Providers can classify asthma as mild intermittent, mild persistent, moderate persistent, and severe persistent. Differentiating between these classifications depends on the following:

• Chronicity of general symptoms (difficulty breathing, wheezing, chest tightness, coughing)
• Chronicity of nighttime symptoms
• Interference with daily activities
• Inhaler use
• Measured lung function

When choosing between asthma classifications, mind these rules regarding the above characteristics. If the physician and/or nurse practitioner (NP) does not document one or more of the above criteria, you should code the asthma as unspecified:

Mild intermittent:

• Symptoms last two or fewer days per week;
• Nighttime symptoms occur two or fewer days a month;
• Rescue inhaler use limited to two or fewer days per week;
• No interference with normal activity; and
• Lung function: FEV1 > 80% predicted and normal between exacerbations.

Mild persistent:

• Symptoms last more than two days per week;
• Nighttime symptoms occur three to four times per month;
• Rescue inhaler use more than two days per week, but not daily;
• Minor limitation of normal activity; and
• Lung function: FEV1 > 80% predicted.

Moderate persistent:

• Daily symptoms;
• Nighttime symptoms occur more than once per week, but not nightly;
• Daily rescue inhaler use;
• Some limitation of normal activity; and
• Lung function: FEV1 = 60 - 80% predicted.

Severe persistent:

• Symptoms occur throughout the day;
• Nighttime symptoms occur nightly;
• Rescue inhaler use several times per day;
• Extreme limitation of normal activity; and
• Lung function: FEV1 < 60% predicted.

Remember: The physician or NP must specifically document "status asthmaticus" in order for you to code it. However, you may code asthma with acute exacerbation if the physician documents any acute symptoms of difficulty breathing, wheezing, chest tightness, and/or coughing alongside the asthma diagnosis.