Table 1

Statistical analysis plan

Research objectivesOutcomeCovariatesAnalytical approach
To determine incidence of diarrhoea and consistency of bowel movements during critical illness
To determine the frequency of diarrhoea defined as the proportion of patients with new ICU-acquired diarrhoea
Primary outcome NAThe incidence of diarrhoea will be computed as the number of new cases during ICU stay divided by the person-time at risk.
Descriptive statistics (proportion of patients with diarrhoea) and corresponding 95% CI
WHO-defined diarrhoea
Different definitions of primary outcome
Bristol Stool Chart-defined diarrhoea
Bliss Stool Classification System-defined diarrhoea
To determine risk factors associated with diarrhoea during critical illness Primary outcome Age, sex, APACHE II score, drugs (motility modifiers, opiates, stool softeners), prior gastrointestinal disease, centreLogistic regression
Dependent variable
WHO-defined diarrhoea
Secondary outcomes
Research objective Secondary outcome CovariatesAnalytic approach
To determine the consequences of diarrhoea Dependent variable WHO-defined diarrhoea, age, sex, APACHE II
Cox regression
Time to ICU discharge
Time to hospital discharge
MortalityLogistic regression
Research objective Secondary outcome Covariates Analytical approach
To determine the incidence of Clostridium difficile-associated diarrhoea (CDAD) during critical illnessIDSA-defined CDADNADescriptive statistics (proportion of cases with diarrhoea during study period)
ACG-defined CDAD
To determine agreement between WHO and
Bristol and Bliss scores
Chance corrected agreement (kappa score)NAKappa statistic with 95% CI
  •  APACHE II, Acute Physiology and Chronic Health Evaluation II; ACG, American College of Gastroenterology ; ESCMID, European Society of Clinical Microbiology and Infectious Diseases ; ICU, intensive care unit; IDSA, Infectious Disease Society of America ; NA, not applicable; CDAD, Clostridium-difficile associated diarrhoea.