New Study Questions Classification of “Severe” CDI in Elderly Patients

Advanced dementia and serum albumin levels were better predictors of poor outcomes, the investigators said, among older patients with Clostridioides difficile infection (CDI).

A new report suggests the definition used to classify “severe” Clostridioides difficile infection (CDI) is not a useful predictor of poor outcomes in elderly adults.

Instead, according to the report, a patient’s serum albumin level and the presence of advanced dementia are more likely to suggest a patient is at high risk. The study was published in Aging Clinical and Experimental Research.

Patients of any age can get CDI, but it is most common in older people, and elderly individuals are more likely to develop severe infections and die from those infections. Yet, the investigators explained that CDI can look different in younger and older patients, in part because older patients have inflammatory systems blunted by the aging process.

The difference in presentation caused the investigators to wonder whether the metrics currently used to define severe CDI in all patients are adequate for the higher-risk age group.

As of 2017, the Infectious Diseases Society of America (IDSA) categorizes CDI as severe based on 2 markers: leukocytosis ≥15,000 cells/mcL or a serum creatinine level above 1.5 mg/dL. The authors noted that existing research suggests older patients have lower rates of leukocytosis but are more likely to have renal failure and altered mental states.

To better understand the risk of negative outcomes in older patients, the investigators performed a retrospective analysis of 853 patients who were hospitalized between January 2013 and May 2020 with CDI. The patients were split into 2 groups based on age: 65 years and older and younger than 65 years. The primary outcome was a composite of 30-day mortality, colectomy due to severe colitis, or intensive care unit admission.

Of the 571 patients in the older group, 93 (16%) experienced the study’s primary outcome compared with 31 (11%) of the patients in the younger group. Looking at mortality, 116 patients (20%) in the older group died within 90 days vs 30 patients (11%) in the younger group.

“In this retrospective study, we found that poor outcomes of CDI are significantly more common among older vs younger adults,” the authors wrote.

Next, the team sought to examine predictors of poor outcomes. A multivariate analysis showed that the IDSA metrics had only an odds ratio (OR) of 1.2 for poor outcomes (95% CI, 0.7-2.2; P = .5). The authors said leukocytosis ≥15,000 cells/mcL was uncommon among patients in the study with poor outcomes, although the rate of patients with serum creatinine levels above 1.5 mg/dL was significantly higher among those with poor outcomes.

“We also demonstrated that serum creatinine >1.5 mg/dL significantly correlated with CDI poor outcomes, considering that patients with poorer outcomes had higher rates of preexisting chronic kidney disease, probably representing patients with more severe baseline comorbidity,” they wrote.

Meanwhile, the authors found that the presence of advanced dementia was much more likely to correlate with poor outcomes (OR, 3.0; 95% CI, 1.5-6.0; P = .002), as were low serum albumin levels (OR, 3.1; 95% CI, 1.7-5.8; P <.01).

The authors said their study is the first to identify advanced dementia as a predictor of poor CDI outcomes, and they posited several potential reasons for the link.

“Patients with advanced dementia lack the ability to communicate with the surrounding environment and may therefore progress clinically without searching for medical attention, [the consequence being] a delayed diagnosis,” they explained. “Furthermore, patients with advanced dementia have inadequate dietary intake and feeding problems that may affect drug administration and absorption, leading to suboptimal treatment response.”

The reason for the serum albumin association, they said, may be because serum albumin is believed to be a component of the host defense mechanism against CDI.

The authors concluded by stating that physicians ought to consider factors outside of the IDSA definition when evaluating older patients, especially the 2 factors identified in this study.


Atamna A, Babich T, Margalit I, et al. Does accepted definition of Clostridioides difficile infection (CDI) severity predict poor outcomes in older adults? Aging Clin Exp Res. Published online August 23, 2021. doi:10.1007/s40520-021-01953-5

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