Comorbidity	ICD-9-CM code(s)
Comorbidities in year prior to CDI encounter
Hypertension	401-405
Dyslipidemia	272
Obesity	278
Myocardial infarction	410, 412
Congestive heart failure	428
Peripheral vascular disease	441, 443.9, 785.4, V43.4
Cerebrovascular disease	430-438
Dementia	290
COPD	490-496, 500-505, 506.4
Rheumatologic disease	710.0-710.1, 710.4, 714.0-714.2, 714.81, 725
Peptic ulcer disease	531.0-531.9, 532.0-532.9, 533.0-533.9, 534.0-534.9
Liver disease	571.2, 571.4, 571.5, 571.6, 572.2-572.8, 456.0-456.21
Diabetes	250.0-250.3, 250.4, 250.5, 250.6, 250.7, 250.8, 250.9
Hemiplegia or paraplegia	342, 344.1
Renal disease	582, 583, 585, 586, 588
Neoplastic disease	140-172, 174-208
HIV/AIDS	42-44, V08
Bacteremia	790.7
Pneumonia	480.0-483.99, 485–487
Skin infection	680-686
Endocarditis	421.0, 421.1, 421.9, 424.9
Urinary tract infection	590-599
Device-related infection	996.31, 996.62, 996.64, 999.31
Acute respiratory infection	460-466
GERD	530.11, 530.81
Transplant	V42, E878.0
Inflammatory bowel disease	555, 556
CDI severity indicators
Shock	639.5, 785.52, 785.59
Sepsis/septicemia	020.2, 038.0-038.9, 995.91, 995.92
Perforation of intestine	569.83
Prolonged ileus	560.1
Megacolon	558.2, 564.7
Acute renal failure	584, 586

AIDS = acquired immune deficiency syndrome; CDI = Clostridium difficile infection; COPD = chronic obstructive pulmonary disease; GERD = gastroesophageal reflux disease; HIV = human immunodeficiency syndrome; ICD-9-CM = International Classification of Diseases, Ninth Revision, Clinical Modification.