Clinical and pharmacoeconomic evaluation of fidaxomicin in patients over 65 years of age and immunocompromised patients with recurrent and refractory Clostridioides difficile infection

Background Recurrent or refractory Clostridioides difficile infection (CDI) often affects older and immunocompromised patients, posing clinical and economic challenges. While fidaxomicin has shown lower recurrence rates than vancomycin in the general population, evidence in this population remains limited. Methods This retrospective, multicentre case-control study compared patients aged > 65 years or immunocompromised patients receiving fidaxomicin (case group) with those treated with vancomycin (control group) for recurrent or refractory CDI. A microcosting approach was used to assess direct treatment costs. Results A total of 344 patients were included (172 per group). Compared to the control group, the fidaxomicin group presented a significantly higher rate of symptom reduction on day 10 (n = 163, 95% vs. n = 147, 86%; p = 0.004) and lower CDI recurrence rates (n = 36, 21% vs. n = 63, 37%; p = 0.001). While the mean CDI treatment costs per patient were significantly higher in the fidaxomicin group (p < 0.001), the hospitalisation and overall treatment costs were comparable (€19,898, 95% CI €16,151-€23,645 vs. €20,469, 95% CI €16,837-€24,101, p = 0.811; €17,798, 95% CI €14,620-€20,975 vs. €17,300, 95% CI €14,199-€20,400, p = 0.840). Key cost drivers were hospitalisation, intensive care unit treatment, and severe initial CDI. Conclusions Despite higher drug acquisition costs of fidaxomicin, overall treatment costs were comparable between the two groups with better clinical outcomes in patients treated with fidaxomicin.