Social Determinants of Health Shape Outcomes in C difficile Infections

Social determinants of health (SDOH) can have a profound impact on the severity and outcomes of Clostridioides difficile (C difficile) infection (CDI), explained Jacinda Abdul-Mutakabbir, PharmD, MPH, AAHIVP, during Peggy Lillis Foundation’s State of C diff Town Hall in November. Abdul-Mutakabbir, assistant professor of clinical pharmacy at the University of California San Diego, discussed a study she participated in conducting while working at Loma Linda University Medical Center (LLUMC) in San Bernardino County, California, that focuses on CDI in the San Bernardino County region, which is predominantly populated by racially and ethnically minoritized (REM) individuals who face significant health disparities.¹

“San Bernardino County is located in the Inland Empire, which is vastly cheaper than living in Los Angeles or San Diego or some of those areas that are more expensive in Southern California,” Abdul-Mutakabbir said. “We do see a mass exodus from those areas, especially with gentrification, which is why [San Bernardino County] is majorly populated by REM individuals. REM residents report the lowest median income and are more likely to reside in areas of lower socioeconomic status of the major counties in Southern California, and San Bernardino County has the highest rate of REM individuals diagnosed with chronic co-morbidities.”¹

A microscopic view of Clostridium difficile bacteria. Image Credit: © Ratchadaporn - stock.adobe.com

San Bernardino County is home to 70% REM residents, including Black/African Americans and Hispanic/Latinos, who are disproportionately affected by chronic conditions such as hypertension, diabetes, and chronic kidney disease (CKD), Abdul-Mutakabbir explained. These populations also experience barriers such as limited health care access and lower socioeconomic status (SES), all of which can exacerbate CDI outcomes, according to Abdul-Mutakabbir.¹

“In San Bernardino County, REM residents are more likely to be uninsured and less likely to have access to a primary care physician,” Abdul-Mutakabbir said. “When we consider C difficile, it's associated with prolonged hospitalizations and mortality. However, recent data indicate that patients who are uninsured or underinsured are more likely to be diagnosed with CDI. Furthermore, when we think about folks with preexisting diseases like high blood pressure or diabetes, these have also been shown to contribute to poor CDI outcomes.”¹

This study conducted at LLUMC also builds upon Abdul-Mutakabbir’s previous work, which identified racial disparities in CDI treatment and outcomes. With its expanded scope, the research at LLUMC employed the CDC’s Social Vulnerability Index (SVI) to analyze neighborhood-level vulnerability based on 4 themes: SES, REM status, household composition and disability (HCD), and housing type and transportation (H&T).^1,2

The retrospective cohort study included 206 adult patients diagnosed with CDI at LLUMC between January 2020 and June 2021. Participants were grouped into 2 categories based on SVI scores: low-to-medium vulnerability and medium-high-to-high vulnerability. Patients residing outside San Bernardino and Riverside counties or without identifiable census data were excluded. Among the included patients, the median age was 62 years, and 51.5% identified as female. The majority of participants (93.7%) were from REM groups, with 40.3% identifying as Hispanic/Latino, 13.6% as Black, and 2.9% as White.^1,2

The study’s results revealed stark disparities in CDI outcomes among high-vulnerability patients. Individuals with high vulnerability scores across SES, HCD, REM, and H&T were significantly more likely to experience severe or fulminant CDI and higher mortality rates. Specifically, 81.2% of patients with severe CDI and 78.9% with fulminant CDI had high vulnerability scores. All-cause mortality was also observed in 20 patients, of whom 90% were in the high-vulnerability group.^1,2

Further analysis showed that REM status was a key driver, with severe CDI leading to a 15 times greater frequency and fulminant CDI leading to a 37 times greater frequency among high-vulnerability groups compared to low-vulnerability groups. SES, household composition, and housing factors also contributed significantly to poor CDI outcomes.^1,2

Jacinda Abdul-Mutakabbir, PharmD, MPH, AAHIVP, is an assistant professor of clinical pharmacy at University of California San Diego Skaggs School of Pharmacy and Pharmaceutical Sciences as well as the Division of the Black Diaspora and African American Studies. She recently received the Infectious Diseases Society of America (IDSA) Society Award in Clinical Practice Innovation and is the second pharmacist in IDSA history to receive a society award and the first Black pharmacist to receive this award. Abdul-Mutakabbir is also an editorial advisory board member and associate editor for Pharmacy Practice in Focus: Health Systems.

Abdul-Mutakabbir noted that these findings underscore the interplay between chronic disease burden, limited health care access, and socioeconomic barriers in driving health disparities. The study also highlighted CKD, often a result of uncontrolled diabetes, as a major mediator of CDI severity. According to Abdul-Mutakabbir, this aligns with the broader understanding that chronic conditions disproportionately affect underserved communities because of inadequate health care resources.¹

“In our REM cohorts, the individuals were younger, they were more likely to be underinsured—meaning they had Medicare, Medicaid, governmental-issued insurance, or no private insurance, they were more likely to have higher rates of diabetes, they were more likely to have higher rates of CKD, and they had higher rates of a severe presentation of C difficile. Then what we continued to see was that our REM individuals were shown to be at 1.6 increased odds of severe or permanent CDI, when compared to the non-REM patients, and we saw that 10% of this was actually mediated by preexisting CKD,” Abdul-Mutakabbir said. “Ultimately, what we saw was the existence of another disease state. So, CKD—which is oftentimes mediated by being diagnosed with diabetes and that diabetes progressing due to less access to health care—well, CKD is contributing to C difficile, so we can see that there is definitely a problem.”¹

While the study provides valuable insights, Abdul-Mutakabbir also noted there were limitations.¹

“A limitation of this study, of course, is that it's single center, so only at Loma Linda and retrospective in its design. It was also not necessarily detected or powered to detect differences in mortality. An additional limitation was the low number of low vulnerability patients, but that is because Loma Linda is located in a highly disparaged area, so we're more likely to get those folks that are most disparaged,” Abdul-Mutakabbir said. “Nonetheless, we do believe that these data will provide a basis for interventions designed to address C difficile disparities at Loma Linda. However, we do understand that further research in this area is warranted and needed.”¹

Additionally, Abdul-Mutakabbir emphasized the importance of integrating social vulnerability data into health care strategies to improve CDI outcomes, particularly for REM populations.¹

“Ultimately, what we see is that patients residing in areas of high vulnerability with susceptible household compositions face socioeconomic obstacles that affect CDI severity,” Abdul-Mutakabbir said. “High vulnerability scores across SES, HCD, REM status, and H&T are correlated with increased CDI severity and mortality rates.”^1,2

REFERENCES

1. Abdul-Mutakabbir J. State of C diff Town Hall. November 20, 2024. Accessed November 20, 2024. https://cdiff.org/event/townhall24/#:~:text=STATE%20OF%20C.-,DIFF,virtual%20event%20on%20November%2020.&text=REGISTER%20NOW-,The%20State%20of%20C.,also%20feature%20a%20patient%20speaker.

2. Lee JM, Zhou AY, Ortiz-Gratacos NM, Al Isso A, Tan KK, Abdul-Mutakabbir JC. Examining the impact of racial disparities on Clostridioides difficile infection outcomes at a Southern California academic teaching hospital. Infect Control Hosp Epidemiol. doi:10.1017/ice.2023.84