Optimal Treatment for Recurrent Clostridium Difficile (OpTION)

• Determine symptom resolution during treatment without any of the following: diarrhea recurrence; other non-fatal clinical events including severe abdominal pain, toxic megacolon, and colectomy; and death. [ Time Frame: Day 59 for all treatment regimens. ]

  The Primary outcome will be sustained clinical response as measured at study day 59 for all treatment regimens. Sustained clinical response is a composite outcome that includes symptom resolution during treatment without any of the following (as assessed on day 59):

  1. Diarrhea recurrence
  2. Other non-fatal clinical events including severe abdominal pain, toxic megacolon (where diarrhea ceases but is not a beneficial outcome), and colectomy
  3. Death
  
  

• CDI Composite outcome measure [ Time Frame: Day 59 for all treatment regimens. ]
  CDI Composite Outcome Measure (CDI-COM) is sustained clinical response without recurrent CDI (defined as diarrhea plus confirmation of toxigenic C. difficile or its toxins in stool) as measured at study day 59 for all three treatment regimens. Sustained response will be defined using the same composite endpoint criteria as were used in the D-COM outcome but without recurrent CDI on or before day 59.
  
  

Clostridium difficile is the most common cause of healthcare-associated infectious diarrhea among adults in industrialized countries. In addition to diarrhea, C. difficile infection (CDI) may also result in serious complications such as shock, toxic megacolon, colectomy, and death. The Centers for Disease Control and Prevention (CDC) has estimated C. difficile results in 250,000 hospital infections, 14,000 deaths, and $1 billion in excess costs annually. Recurrent CDI is the most challenging clinical dilemma facing clinicians who treat this disease. An estimated 30% of patients who respond to initial treatment with either vancomycin or metronidazole develop recurrent CDI, usually within 1-4 weeks of completing treatment.

The primary objective of this study is to determine whether 1) standard fidaxomicin treatment and 2) standard vancomycin treatment followed by taper and pulse vancomycin treatment are superior to standard vancomycin treatment alone for sustained clinical response at day 59 for all treatments, for participants with either their first or second recurrence of CDI. Veterans presenting with a first or second CDI recurrence will be screened, consented and randomly assigned in a double-blind manner to one of three treatment groups: 1) a 10 day course of oral vancomycin (VAN-TX), 2) a 10 day course of fidaxomicin (FID-TX) or 3) a 31 day course of vancomycin which includes a taper and pulse following daily treatment (VAN-TP/P). Symptom resolution is defined as an improvement or resolution of diarrhea (<3 unformed bowel movements over 24 hours) for 48 consecutive hours compared to the participant's baseline. Recurrence is defined as having diarrhea (>3 loose or semi-formed stools over 24 hours for 48 consecutive hours). A sample size of 546 randomized study participants is required to obtain at least 82% power to detect a 16% absolute difference (expected proportion of 31% in the VAN-TX group) in sustained clinical response (D- COM) proportion 1) between the FID-TX group and the VAN-TX group and 2) between the VAN-TP/P group and VAN-TX group at the 0.05 significance level. The study is expected to complete enrollment in 4 years with 90 days of follow-up. Twenty four sites, including 6 pilot sites, will be required to enroll approximately 0.6 participants per month (7 every year), or 21 participants per site (28 participants per pilot site) over 4 years (546 participants total). This assumes that 30% of Veterans with CDI have a recurrence and 20% of them will enroll in the study.