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Table 5 Patient characteristics in the motivating example of the International Mission for Prognosis and Analysis of Clinical Trials (IMPACT) dataset with patients grouped based on having received an intracranial pressure monitor

From: Instrumental variable analysis to estimate treatment effects: a simulation study showing potential benefits of conditioning on hospital

Ā 

Intracranial pressure monitor

(nĀ =ā€‰3009)

No intracranial pressure monitor

(nĀ =ā€‰4543)

Age (median, IQR)

34 (23-88)

27 (20-39)

Male sex

2385 (79%)

3510 (77%)

GCS motor score (median, IQR)

4 (2-5)

4 (2-5)

Pupillary reactivity

ā€ƒ-Both pupils reactive

1822 (61%)

3130 (69%)

ā€ƒ-One pupil reactive

575 (19%)

580 (13%)

ā€ƒ-No pupil reactive

612 (20%)

833 (18%)

CT classificationb

ā€ƒ-Normal

42 (1%)

373 (8%)

ā€ƒ-Diffuse II

506 (17%)

62,285 (50%)

ā€ƒ-Diffuse III

473 (16%)

996 (22%)

ā€ƒ-Diffuse IV

122 (4%)

180 (4%)

ā€ƒ-Mass lesion

1866 (62%)

709 (16%)

tSAH

1511 (50%)

1904 (42%)

GOSa

ā€ƒ-Death

832 (28%)

1666 (37%)

ā€ƒ-Persistent vegetative state

566 (19%)

977 (22%)

ā€ƒ-Severe disability

559 (19%)

724 (16%)

ā€ƒ-Moderate disability

161 (5%)

199 (4%)

ā€ƒ-Good recovery

891 (30%)

977 (22%)

  1. Table presents values after data imputation. Values are presented as n (%) unless otherwise specified
  2. a GOS: Glasgow Outcome Scale as outcome after 6ā€‰months
  3. b CT classification is based on the Marshall classification. Diffuse II refers to CT abnormalities without swelling or shift; Diffuse III refers to CT abnormalities with swelling (compressed cisterns); Diffuse IV refers to CT abnormalities with a shift