Black Patients Receive Less C Diff Tests Despite Similar Positivity Rates to White Patients

Bobby Warren, MPS

Credit: Duke Center for Antimicrobial Stewardship and Infection Prevention

Results from a retrospective cohort study of inpatient Clostridioides difficile infection (CDI) testing at 3 hospitals in North Carolina are calling attention to racial disparities in test administration.

Greater rates of CDI testing were observed among White patients compared to Black or non-White non-Black (NWNB) patients when controlling for race-specific patient days, suggesting inequity in testing based on race.¹

“Previous studies have included evidence of differing CDI risk between races and by healthcare access and utilization, with White individuals having higher exposure to C. difficile and receiving more tests,” wrote investigators.¹ “However, these studies were based on error-prone hospital discharge surveys, and few studies have controlled for disproportionate time spent in the hospital between races.”

The US Centers for Disease Control and Prevention estimates Clostridioides difficile causes approximately 500,000 infections in the US each year. Risk factors include being aged 65 years or older, a recent stay at a hospital or nursing home, a weakened immune system, and previous infection with Clostridioides difficile or known exposure. Testing is necessary to identify and contain CDI cases, especially in inpatient settings - however, disparities in testing and positivity rates based on race may pose important implications.²

A team of investigators led by Bobby Warren, MPS, lab director of the Disinfection, Resistance and Transmission Epidemiology (DiRTE) Lab at Duke Antimicrobial Stewardship Outreach Network, sought to build upon previous research using electronic health record data to assess racial disparities in CDI testing while controlling for disproportionate patient days between races using race-specific patient days. Inpatient encounters from 3 hospitals in the Duke University Health System between January 1, 2015, and December 31, 2021, were examined for CDI testing and proportions of positive tests by race, hospital, and year.¹

Investigators defined an inpatient encounter as a unique encounter with exposure to an inpatient unit for at least 1 calendar day. Self-reported race data were extracted from electronic health records and were categorized into 3 groups: White, Black, and NWNB. Patients were excluded from the study if race was not listed or the respondent declined to answer.¹

Unique CDI tests were defined by laboratory accession numbers, with PCR tests used to identify CDI. Duplicate tests were defined as those occurring within 14 days of a previous test or positive result according to the NHSN LabID Event Protocol. Of note, repeated tests were included in the study. The primary outcome of interest was the number of CDI tests administered by race per 1,000 race-specific patient days, while the secondary outcome was percent positivity by race.¹

Hospital A, a 1,048-bed facility, was an academic medical center, whereas hospitals B (388 beds) and C (186 beds) are academically affiliated hospitals. In total, 35,160 CDI tests and 2,571,850 patient days across all 3 hospitals were included in the study. Of the study hospitals, hospital A administered 25,007 tests during 1,805,225 patient days. Hospital B administered 6,691 tests during 416,352 patient days and hospital C administered 3,462 tests during 350,273 patient days.¹

White patients received the most CDI tests (21,695), followed by patients who identified as Black (11,846) and those who identified as NWNB (1,619). The median number of CDI tests per 1,000 patient days was 13.85 (interquartile range [IQR], 9.88-16.07). Among all CDI tests, 5,225 (15%) were positive, including 3,428 from hospital A, 1,202 from hospital B, and 595 from hospital C.¹

White patients accounted for 3,222 (62%) positive tests, Black patients had 1,803 (35%) positive tests, and NWNB patients had 200 (4%) positive tests. Across the total surveillance period, an aggregate of 2,571,850 patient days were included: 1,499,993 patient days (58%) were attributed to White patients, 914,228 (36%) were attributed to Black patients, and 157,629 (6%) were attributed to NWNB patients.¹

When controlling for patient days by race, investigators noted White patients were administered more CDI tests (14.46 per 1,000 patient days) than Black patients (12.96 per 1,000 patient days; P < .0001) and NWNB patients (10.27 per 1,000 patient days; P < .0001). Further analysis revealed white patients tested positive at a greater rate than NWNB patients (15% vs 12%; P = .0061) but at a similar rate to Black patients (15% vs 15%; P = .3655).¹

“We observed lower rates of CDI testing among Black patients after adjustment for race-specific patient days and despite similar rates of test positivity across groups, which could be the result of inequity in testing or of a lower incidence of C. difficile disease among Black inpatients. Further research is needed to understand why this difference occurred, if this is geographically dependent, and if it results from differences in either access to care or in selection for testing,” concluded investigators.¹

References:

1. Warren B, Burch C, Barrett A, et al. Racial disparities in Clostridioides difficile testing in three southeastern US hospitals. Infection Control & Hospital Epidemiology, 1-5. doi:10.1017/ice.2023.244
2. Centers for Disease Control and Prevention. What is C. diff? C. diff (Clostridioides difficile). September 7, 2022. Accessed November 27, 2023. https://www.cdc.gov/cdiff/what-is.html