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Objective: demonstrating clinical efficacy
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Objective: understanding disease mechanisms, suggesting intervention strategies(guiding clinical trials), examining potential efficacy, safety and toxicity of interventions
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Disease naturally present
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Disease often induced (with unclear/insufficient similarity to the human condition)
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Timing of applying the intervention in relation to the disease onset is often heterogeneous
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Intervention is often applied at a known time point in relation to the induced disease state
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Often a heterogeneous group of patients (for example, lifestyle and co-morbidities)
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Often a considerably homogeneous study population (e.g., comparable/controlled housing conditions and animal characteristics such as genetic backgrounds, gender, and presence of co-morbidities)
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Sample size relatively large (compared to animal studies)**
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Sample size relatively small (compared to RCTs) and sample size calculations often not reported
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In general, relatively high internal validity because of randomization and blinding (compared to animal studies)**
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In general, low internal validity (compared to RCTs)
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E.g., not yet standard practice to:
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-Randomize allocation of the animal to the intervention and control groups
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-Blind personnel and outcome assessors
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Patients can be blinded for treatment in many situations.
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Animals cannot and need not be blinded for treatment.
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Relatively high external validity (extrapolation within one species)
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Relatively low external validity (extrapolation between different species)
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Relatively large teams involved
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Relatively small teams involved
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Intervention staffs are often different from outcome assessment staff.
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One researcher is often responsible for treatment allocation and administration, outcome assessment and data analysis.
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In general, no post-mortem data
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In general, post-mortem material available
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Animals are often sacrificed at the end of the experiment.
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Outcomes are often patient-relevant outcomes (compared to animal studies)
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Outcomes are often surrogate outcomes, and still difficult to translate to the clinical setting even if similar to clinical outcomes
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Clear guidelines for reporting and methodological quality [25]
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Evolving guidelines for reporting and methodological quality [2, 23, 24]
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