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Table 1 Extracted variables

From: Impact of methodology on estrogens’ effects on cerebral ischemia in rats: an updated meta-analysis

Factor/outcome measure Data type Final categories/unit Reference category for regression analyses
Rat properties
Strain Category I. Sprague Dawley Sprague Dawley
II. Wistar
III. Other strains
Sex Category I. Female Female
II. Male
Diseases Category I. Healthy Healthy
II. Diabetes
III. Hypertension
Elderly rats Category [No] [No]
Number of rats in estrogen treated and control groups Continuous   NA
Estrogen administration
Estrogen administration mode Category I. Slow-release pellets Slow-release pellets
II. Injections
III. Silastic capsules
Estrogen type Category I. 17β-estradiol 17β-estradiol
II. Estradiol valerate
III. Premarin
IV. Estrone
Slow-release pellets: estrogen dose/pellet Continuous μg NA
Injections: Daily estrogen dose Continuous μg/kg body weight NA
Silastic capsules: estrogen dose/silastic capsule Continuous μg NA
Washout (Length of time between ovariectomy and estrogen administration) Category I. 014 days 0-14 days
II. >14 days
Length of time between initiation of estrogen administration and induction of the ischemic damage Continuous Hours NA
Focal ischemia procedure
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. Permanent Permanent
II. Short transient (up to 60 minutes)
III. Long transient (>60 min)
Laser-Doppler flowmetry during surgery Category [No] [No]
Analysis procedure
Length of time between ischemia and evaluation of damage Edema correction Continuous Hours NA
Edema correction Category I. No edema correction used No edema correction used
II. Correcting for edema in infarct
III. Correcting for edema in entire hemisphere
Outcome measures
Infarct size ratio between estrogen treated and control rats – “EC-ratio” Continuous % NA