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Table 1 Extracted factors and outcome measures

From: Method parameters’ impact on mortality and variability in rat stroke experiments: a meta-analysis

Factor/Outcome measure Data type Final categories* or unit Reference category for regression analyses
Rat property factors
Strain Category I. Sprague Dawley Sprague Dawley
II. Wistar
V. Other strains
Sex Category I. Male Male
II. Female
III. Ovx female
IV. Mix or not specified
Elderly rats ** Category, Binomial [No] [No]
Weight Continuous Grams NA
Animal exclusion rate Continuous % NA
Anesthesia factors
Type of anesthetic Category I. Inhalation anesthetic Inhalation anesthetic
II. Chloral hydrate
III. Ketamine
IV. Barbiturates and benzodiazepines
V. Other anesthetics
Intubation Category, Binomial [No] [No]
Awakening of rats during occlusion Category, Binomial [No] [No]
Temperature feedback system Category, Binomial [No] [No]
Electroencephalographic surveillance Category, Binomial [No] [No]
Blood pressure monitored Category, Binomial [No] [No]
Heart rate monitored Category, Binomial [No] [No]
Blood gases/O 2 saturation analyzed Category, Binomial [No] [No]
Blood hemoglobin concentration analyzed Category, Binomial [No] [No]
Blood glucose concentration analyzed Category, Binomial [No] [No]
Postoperative antibiotics Category, Binomial [No] [No]
Focal ischemia procedure factors
Type of middle cerebral artery occlusion procedure Category I. Intraluminal filament Intraluminal filament
II. Direct, mechanical***
III. Embolic
IV. Photothrombotic
V. Endothelin injection
Occlusion duration**** Category I. Short transient (up to 60 minutes) Short transient (up to 60 minutes)
II. Long transient (>60 min)
III. Permanent
Occluding filament type (Only studies using the intraluminal filament method) Category I. Uncoated Uncoated
II. Silicon coated
III. Poly-L-Lysine coated
IV. Other coatings
Analysis procedure factors
Time after focal ischemia for evaluation of damage Continuous Hours NA
Type of infarct size evaluation Category I. TTC TTC
II. Radiology
III. Acidic/Basic stain or silver stain histology
IV. Immunohistology
Edema correction used Category, Binomial [No] [No]
Blinding of infarct size determination procedure Category, Binomial [No] [No]
Criteria for excluding rats Category I. None None
II. Observed absence of cerebral blood flow reduction
III. Lack of functional deficit
IV. Too small infarct
V. Other pathology in animal
Outcome measures
Infarct size coefficient of variation Continuous % NA
Mortality rate Continuous % NA
  1. * Only categories represented by at least 5 control groups were included in the analysis to avoid statistically inadequate attribution of explanatory value to too small categories. Categories represented by less than 5 control groups were in the analysis included in an Others category. Further, some other reductions in number of categories were performed, as presented below.
  2. ** Elderly rats were defined as being >12 months of age at time of ischemic insult.
  3. *** Direct, mechanical refers to all MCAo procedures where the MCA is mechanically occluded from the outside, for example by clips, cauterization or ligation.
  4. **** Only methods including actions taken to ensure reperfusion (such as removing the occluding intraluminal filament or arterial clip) were considered transient.