ICD-9-CM diagnosis code (retired)
491.21 — Obstructive chronic bronchitis with (acute) exacerbation
ICD-9-CM was replaced by ICD-10 on October 1, 2015. These are the ICD-10-CM equivalents from the CMS General Equivalence Mappings.
About ICD-9-CM 491.21
491.21 is an ICD-9-CM diagnosis code for obstructive chronic bronchitis with (acute) exacerbation. ICD-9-CM was retired for U.S. claims on October 1, 2015, when ICD-10-CM took over.
The CMS General Equivalence Mappings translate it to one ICD-10-CM code, J44.1 (Chronic obstructive pulmonary disease with (acute) exacerbation). The match is approximate, so confirm it against the record.
ICD-10-CM equivalents
- J44.1Chronic obstructive pulmonary disease with (acute) exacerbationapproximate
Common questions about 491.21
What is the ICD-10 code for ICD-9 491.21?
- The GEMs map 491.21 to ICD-10-CM J44.1.
GEMs are a translation aid, not a substitute for coding from the record. The 2027 ICD-10 code set has changed since the last GEMs release in 2018. Page updated September 29, 2026.