Extended criteria (experimental). This is the broader ten-condition engine, kept as a secondary area. It shows ICD-10-CM codes and illustrative grouping effects for CDI staff. The primary surface is Before you sign (kidney, measurement only). All extended pages.

Obesity class from BMI

Rule obesity version 2026.11-1 · condition: Obesity

Published source

CDC: Adult BMI Categories (2024). Class 1: 30 to <35; class 2: 35 to <40; class 3: 40 or higher (adults aged 20 and over). https://www.cdc.gov/bmi/adult-calculator/bmi-categories.html · public page checked 2026-11-14

Inputs

bmi: BMI from charted height and weight (kg/m2)
age: Age (years)

Thresholds

t.adult: 20
t.c1: 30
t.c2: 35
t.c3: 40

Outcomes

First true outcome wins; an unknown input makes an outcome unknown
Outcome	When	Status	Supports
not_adult Adult BMI categories apply from age 20	`age < t.adult`	judgement	—
class3 BMI {bmi} (class 3)	`bmi >= t.c3`	supported	E66.813 Obesity, class 3
class2 BMI {bmi} (class 2)	`bmi >= t.c2`	supported	E66.812 Obesity, class 2
class1 BMI {bmi} (class 1)	`bmi >= t.c1`	supported	E66.811 Obesity, class 1
not_met BMI {bmi}, below 30	`bmi < t.c1`	not_supported	—

ICD-10-CM specificity ladder (FY2026 CC/MCC status as a secondary diagnosis)

E66.9 Obesity, unspecified · non-CC
E66.01 Morbid (severe) obesity due to excess calories · non-CC (refines E66.9)
E66.811 Obesity, class 1 · non-CC (refines E66.9)
E66.812 Obesity, class 2 · non-CC (refines E66.9)
E66.813 Obesity, class 3 · non-CC (refines E66.9)

Query topic: weight-related documentation · prompts for an undocumented diagnosis: yes

Coding notes

The BMI Z68 code may be taken from other clinicians' documentation, but only when the provider documents an associated condition such as obesity (ICD-10-CM guideline I.B.14).
Z68.41-Z68.45 (BMI 40 or higher) are CCs; E66.811-E66.813 and E66.01 are non-CC (FY2026).