medicare dx code

what dx code can be used with GO424? HCPCS code for Pulmonary Rehabilitation.

re: medicare dx code

As specified in 42 CFR 410.47, Medicare covers pulmonary rehabilitation items and services for patients with moderate to very severe COPD (defined as GOLD classification II, III and IV), when referred by the physician treating the chronic respiratory disease. GOLD Guidelines - 2011 revision
No change in classifications of COPD
GOLD 2-Moderate 50% < FEV1<80% predicted
GOLD 3-Severe 30% < FEV1<50% predicted
GOLD 4-Very Severe FEV1<30% predicted
GOLD classifications are based on post-bronchodilator FEV1
Look at:
491.0; 491.1; 491.20; 491.8; 492.8; 496