A numerical similarity approach for using retired Current Procedural Terminology (CPT) codes for electronic phenotyping in the Scalable Collaborative Infrastructure for a Learning Health System (SCILHS)

Table 2 Possible groupers for “Anesthesia for Caesarean section”

Groupers for Anesthesia for Cesarean section (850)
l	a	b	Name
1	100	1999	Anesthesia
2	800	882	Anesthesia for procedures on the lower abdomen
3	840	851	Anesthesia for intraperitoneal procedures in lower abdomen including laparoscopy

The third (most specific) is chosen by our method. l is hierarchical level, a is the smallest code in this category, and b is the largest code

ISSN: 1472-6947