Initial Vancomycin Taper for the Prevention of Recurrent Clostridium Difficile Infection

STUDY POPULATION

This is a multi-centre study involving institutions in British Columbia, Ontario, Quebec and Newfoundland. The study population will be drawn from patients cared for as inpatients or outpatients at the participating hospitals. Such patients will have a test positive for Clostridium difficile and will be receiving treatment. The trial will involve only adult patients 18 years of age and older.

Criteria for Recruitment

The microbiology laboratory will notify the study team about a positive CDI test via telephone, email, or fax. The nature of recruitment will then depend on the inpatient status of the patient at the time of the test.

Inpatients:

Pre-existing approval for approaching patients for this study will be obtained from the relevant department heads. The study team will speak with a member of the inpatient treating team (resident physician or faculty physician as appropriate) to determine if the patient is appropriate for recruitment. If this seems to be the case, the patient's file will be rapidly screened to determine eligibility and if the patient is eligible they will be approached for consent.

Outpatients:

The physician who ordered the C. difficile test will be contracted to determine if the patient is appropriate for recruitment. At the invitation of this physician, the investigators will then contact the patient via telephone to evaluate suitability for inclusion and arrange an intake visit.

RANDOMIZATION

For patients who have enrolled in the study, randomization will occur centrally at McGill via an existing internet application (such as https://cloudtrials.mchi.mcgill.ca/) and will be performed by permuted block with randomized block sizes. This randomization will be stratified for first episode or first recurrence at study entry to ensure these factors are properly balanced.

TRIAL SCHEDULE

• Day 1: Patient diagnosed with C. difficile and started on standard of care oral vancomycin treatment -> Determine eligibility and obtain permission for approach

• Day 7-10 (Patient's C. difficile has improved and meets eligibility): Consent obtained; randomization; distribution of study drug for day 15 start -> Collection of demographics

• Day 15-28 -> Receipt of study therapy

• Day 28: In person or remote visit

• Day 56: In person or remote visit -> Primary outcome determined, quality of life questionnaire

• Day 90: Study ends for the patient -> Secondary outcomes can be determined

• weekly until Day 56: Brief questionnaire -> By email/text/phone

• biweekly after Day 56: Brief questionnaire -> By email/text/phone

• Ad hoc: If patient has symptoms of recurrence of C. difficile -> Review by ID physician in clinic if possible, otherwise usual doctors or emergency room

Patients will be able to come be assessed for potential relapse by infectious diseases physicians at each site (who may or may not be a part of the study) or could see their usual doctors.

SAMPLE SIZE AND STATISTICAL METHODS

The estimated number of CDI cases available has been based on fiscal year 2016 data: total of 1770 per year.

The risk of recurrence is estimated at 25%. The investigators aim to demonstrate that an initial tapering regimen is associated with an absolute decrease in the risk of relapse of at least 10% (number needed to treat of 10) which would be similar to the effect seen within 40 days in the fidaxomicin trial. This estimate accounts for our longer period of follow up and will allow some flexibility in the actual recurrence rate found in our control arm. With 80% power and a type 1 error of 5%, this would require 276 patients to complete follow up in each arm (total 552).