Where Are They Now? Q&A with Dr. Alyssa Cox

By: Kristina White, PharmD, BCPS, BCIDP

Dr. Alyssa Cox, PharmD 

Dr. Cox is an Oncology Infectious Diseases Clinical Pharmacy Specialist at Memorial Hospital West. She completed her PGY-1 residency at AdventHealth Orlando and her PGY-2 residency in Infectious Diseases at Memorial Hospital West. Her interests include Immunocompromised populations and gram-negative resistance.

Recent Research includes:  Assessment of Vancomycin versus Fidaxomicin for Treatment of First Occurrence Clostridioides difficile Infection in Patients at High Risk of Recurrence 

The objective of the study was to investigate the incidence of Clostridioides difficile infection (CDI) recurrence in high-risk patients treated with either fidaxomicin (FDX) or vancomycin (VAN). This observational, multicenter, retrospective study conducted from August 2021 to August 2024 assessed outcomes of 176 high-risk patients (FDX = 76, VAN = 100). Those who received FDX were less likely to experience recurrent CDI within 90 days (7.9% vs 19.0%, p = 0.037) with no difference in 30-day all-cause mortality. After adjusting for confounders, treatment with FDX was significantly associated with a 68.3% lower likelihood of 90-day recurrence compared with VAN, which supports guidelines recommendations. 

1. What led your group to investigate fidaxomicin vs. vancomycin in those who were at risk for C.diff recurrence?  

The IDSA provided a focused update in 2021 for the treatment of CDI, recommending FDX over VAN for initial CDI episode based on the results of 2 recently published randomized controlled trials. However, there was limited representation of patients who are the highest risk of recurrent CDI (immunosuppressed patients and those with severe CDI) in these studies. The IDSA notes this as a limitation; therefore, a focused evaluation on high-risk patients with first episode of CDI was warranted to determine the applicability of these recommendations in this population. 

2. Did any of the findings surprise you? 

The most surprising result from our study was the potential impact of prior hospitalization on rates of recurrence. To account for potential confounding variables, we conducted a multivariable logistic regression on the group of patients who experienced a recurrent episode within 90 days. The variables included in the regression model were prior hospitalization and treatment group. The results showed that patients treated with fidaxomicin had 68.3% lower odds of having a recurrent episode. We also saw that prior hospitalization was an independent risk factor for increasing odds of recurrence. 

3. How have the results of your study impacted your practice? 

With the continued good results of FDX in addition to guideline support, I think there will be an increased use at our hospital, specifically for patients at high risk for recurrence with their first episode of CDI, since this is what our study focused on. Currently, FDX is a restricted antimicrobial at our hospital due to cost. Our current criteria for use includes patients who have recurrent episodes and have failed VAN, and high-risk patients (age 65 years and older, immunosuppressed, and severe CDI). Our study did not complete a cost analysis, but the results showed that those who received FDX had a shorter ICU length of stay and fewer CDI-related 30-day readmissions. With FDX likely becoming generic in the near future, in addition to the benefits mentioned above, it is likely that FDX may be a cost-effective option for patients and may lead to expansion of our criteria for use in the future. However, a cost analysis is needed to determine the financial impact. 

4. Based on your research, what are some unanswered questions that you believe should be further investigated? 

The lower likelihood of 90-day recurrence with FDX after adjustment demonstrated by our study is thought-provoking and suggests that prior hospitalization may also need to be considered as a risk factor for recurrence for future studies. additionally, the benefits of reduced hospitalization may outweigh the cost of FDX; however, future studies conducting a cost analysis would be necessary to assess the potential cost savings with FDX. 

The MAD-ID ‘Where Are They Now?’ series highlights research presented at the MAD-ID Annual Meeting now published in the infectious diseases literature.