Table 1 Variable definitions

Age

Calculated based on the patient’s date of birth and date of positive test for C. difficile.

Body Mass Index (BMI)

Patient’s weight (kg) divided by the square of the patient’s height (meters).

Race

White (Caucasian) or non-white (American Indian or Alaska Native; Asian; black or African American; Native Hawaiian or Other Pacific Islander).

Charlson Comorbidity Index

Weighted index to predict the risk of death in patients with specific comorbidities based on the International Classification of Diseases (ICD) diagnosis code, ninth and tenth revisions ICD-9, ICD-10).

Braden Score

Measure of functional capabilities to predict the risk of developing facility-acquired pressure ulcer/injury. Most recent score within 90 days prior to the positive C. difficile test.

Comorbidities

History of diabetes mellitus, cancer, cirrhosis, inflammatory bowel disease (ulcerative colitis or Crohn’s disease). Based on ICD-9 and ICD-10.

Gastrointestinal Procedures

Endoscopy or gastric tube placement within 15 days prior to a positive C. difficile test.

Nasal colonization of methicillin-resistant Staphylococcus aureus, (MRSA)

Nasal-swab screening for methicillin-resistant Staphylococcus aureus (MRSA) within 90 days prior to a positive C. difficile test.

Serum creatinine and peripheral white blood cell count

Most recent test within 90 days prior to a positive C. difficile test.

Serum albumin

Most recent test within 180 days prior to a positive C. difficile test.

High Risk Antibiotics

Defined as days of therapy (DOT) of high-risk antibiotics for CDI (carbapenems, macrolides, clindamycin, fluoroquinolones, piperacillin-tazobactam, 2nd, 3rd, and 4 th generation cephalosporins) during the previous 90 days prior a positive C. difficile test. Piperacillin-tazobactam was recorded in inpatient services only.

Proton pump inhibitors and histamine H2-receptor antagonists

One or more oral/intravenous doses within 90 days before a positive C. difficile test.

Epidemiological Classification

Community-associated: CDI symptom onset in the community or <4 days from admission (day of admission being day 1), provided that symptom onset was >12 weeks after the last discharge from a healthcare facility.

Healthcare-associated: CDI symptom onset ≥4 days after admission to a healthcare facility, with day of admission being day 1, or in the community or <4 days from admission provided that symptom onset was <4 weeks after the last discharge from a healthcare facility.