Table 1.
Nature of Information | Value to the Conception and Design of Clinical Trials |
---|---|
Case counts for previous outbreaks | Serves as rudimentary estimate of the feasibility of sample-size requirements. Clinical trial groups should prioritize the most efficient trial designs when a low number of cases is expected. |
Temporal and geographical profile of previous outbreaks | This is required for logistical planning, to ensure that local teams are sufficiently trained in research practices (such as good clinical practice) and trial-specific equipment is available. |
An agreed-upon case definition | Clinical characteristics of the disease are used to define enrollment criteria. |
Analysis of strength of evidence for factors associated with increased disease severity or fatality | Stratification (or other statistical adjustment) on the basis of severity is often required when interpreting the clinical trial outcome. |
Best available descriptions of the type and rate of clinical outcomes | Clinical outcomes will function as a trial outcome measures. Understanding the natural course of illness will also help differentiate disease course from adverse events from treatment. |
Assessment of confidence in estimates of clinical outcomes | Heterogeneity in patient outcomes between or within outbreaks creates uncertainty for power calculations and will affect selection of a statistical design for a trial. Spurious heterogeneity may occur due to random error in small cohorts, or represent ascertainment, lead-time, measurement, or follow-up bias. Real heterogeneity can occur due to improvements in care over an outbreak, pathogen evolution, or changes in host susceptibility and vulnerability but should be adjusted for. |
Analysis of known or suspected covariates of outcome | Highlights possible confounders that will alter outcome independently of treatment and that will require adjustment if unequally distributed between treatment and control arms. |
The mean time from onset of symptoms to outcome | Allows for an estimation of the feasibility and logistics of medical intervention. |
Agreed-upon standards of care for patient treatment | Determines if there is standardized supportive therapy to be adopted in all arms of a trial. This is especially important for multicenter research |
The performance characteristics of the favored diagnostic method | Determines whether a trial will be performed on an ITT basis or following laboratory confirmation. |
Mean time for laboratory diagnosis | Determines whether a trial will be performed on an ITT basis or following laboratory confirmation. |
Community priorities and expectations for trials | Determines the priorities of affected communities in terms of access to trials, acceptable methodology, and acceptability of treatments or vaccines. |
Abbreviation: ITT, intention-to-treat.