Obesity: Understanding the Condition and Its Implications

Definition:

• Obesity: A state of excess storage of body fat.
• Overweight: Refers to excess body weight for height.

Facts and Statistics:

The Centers for Disease Control (CDC) reported in August 2024 that more than 100 million U.S. adults aged 20 or older have obesity, with 22 million classified as severely obese. Additionally, 14.7 million cases of obesity have been reported in U.S. children and adolescents aged 2-19. The National Center for Health Statistics shows that the obesity prevalence in adults (aged 20 and older) rose from 19.4% in 1997 to 31.4% by the reporting period of January-September 2017.

Diagnostic Criteria:

• Underweight: BMI < 18.5 kg/m²
• Normal Weight: BMI 18.5–24.9 kg/m²
• Overweight: BMI 25–29.9 kg/m²
• Obesity (Class 1): BMI 30–34.9 kg/m²
• Obesity (Class 2): BMI 35–39.9 kg/m²
• Extreme Obesity (Class 3): BMI > 40 kg/m²

Note: Morbid obesity is defined by a BMI > 40 kg/m², or a BMI of 35 or higher with at least one weight-related comorbidity, such as diabetes, heart disease, stroke, hypertension, or arthritis.

Diagnostic Tests:

• Fasting Lipid Panel
• Liver Function Studies
• Thyroid Function Tests
• Fasting Glucose and Hemoglobin A1c (HbA1c)

Treatment:

• Nutritional consult
• Counseling on diet and exercise
• Medications such as GLP-1s
• Bariatric surgery procedures
• Treatment for associated comorbid conditions

Coding and CDI Considerations:

Overweight and obesity codes are found in category E66. An instructional note directs the reporting of BMI, if known, as an additional diagnosis (adults: Z68.1-Z68.45; pediatrics: Z68.5-).

Code E66.01 classifies morbid (severe) obesity due to excess calories. Documentation of "severe" obesity allows the assignment of this code. However, E66.01 has an Excludes1 note that it should not be coded with E66.2, which refers to morbid obesity with alveolar hypoventilation.

BMI codes can be taken from non-physician documentation, but the physician must provide an associated diagnosis.

IPPS FY 2025 New Codes for Obesity:

• E66.811 Obesity, Class 1
• E66.812 Obesity, Class 2
• E66.813 Obesity, Class 3 (synonymous with morbid obesity)
• E66.89 Other obesity, not elsewhere classified

Current coding guidance states that obesity and morbid obesity are always clinically significant and should be reported when documented. No additional documentation is required to support clinical significance for this condition (such as evaluation, treatment, or increased monitoring).

Obesity and Comorbid Conditions:

CDI specialists should review for obesity-related comorbid conditions, such as:

• Obstructive sleep apnea (OSA)
• Malignancy
• Coronary artery disease (CAD)
• Hypertension (HTN)
• Gallbladder disease
• Osteoarthritis
• Diabetes
• Stroke
• Depression

If the patient's BMI is 35 or higher and they have a comorbid condition related to obesity, this may be considered morbid obesity. The provider should document the relationship between weight and the comorbid condition to demonstrate the need for specific management and strengthen medical necessity and decision-making. Obesity also impacts risk adjustment methodologies, including Elixhauser and AHRQ PSIs.

Query Example:

Please specify if the condition you are managing can be represented as:

• Morbid Obesity
• Obesity, Class 2
• Other condition (please specify)

The following clinical indicators are noted in documentation:

• RN admission assessment with BMI 38.5
• Nutrition consult ordered
• Chronic conditions of Type II Diabetes and Hypertension

Works Cited

• American Hospital Association. (2018). Coding Clinic for ICD-10-CM/PCS, Fourth Quarter 2018, p. 77.
• Hamdy, O. (2024). Obesity. Medscape. Available at: https://www.medscape.com
• Official ICD-10-CM Coding Guidelines for Coding and Reporting. (FY 2026). Sections I.C.19.a and I.C.19.c. Centers for Medicare & Medicaid Services. Available at: https://www.cms.gov/medicare/coding-billing/icd-10-codes
• Pinson, R., & Tang, C. (2024). Body Mass Index and Obesity. CDI Pocket Guide. CDIPlus.
• Prescott, L., & Manz. (2024). Morbid Obesity. ACDIS Pro.
• U.S. Centers for Disease Control and Prevention. (2024, September 12). New CDC Data Show Adult Obesity Prevalence Remains High. Available at: https://www.cdc.gov/media/releases/2024/p0912-adult-obesity.html