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. Author manuscript; available in PMC: 2016 Jul 1.
Published in final edited form as: Ann Emerg Med. 2015 Jan 14;66(1):30–41.e3. doi: 10.1016/j.annemergmed.2014.12.004

Appendix Table 1.

Shock Cohort: Characteristics in the Imputation and Analysis Models.

The following characteristics were included in imputation models to multiply impute values for those characteristics that were missing for one or more patients.
In analysis models? Characteristic Modeled as ... # Missing Imputation method
Y 28-day mortality Indicator 0
Y EMS Time (minutes)a Categorical: ≤30, 30-45, 46-60, >60 0
Y Age Continuous, spline with knot at 45 years 1 PMM
Y Male gender Indicator 0
Y Penetrating injury Indicator 0
Y ISSb Continuous 31 PMM
Y Qualifying SBP Categorical: ≤50, 51-60, 61-70, 71-80, 81-90 0
Y Highest heart rate (beats/minute) Categorical: <50, 51-110, >110 4 ML
Y Initial GCS Continuous 1 PMM
Y Out-of-hospital advanced airway attempted Indicator 0
Y Air transport Indicator 0
Y Regional site Categorical - fixed effect 0
N Required critical intervention Indicator 0
N ISS disposition category Categorical: Died < 6 hrs, other death, discharge ≥ 2 days, discharge < 2 days, discharge from ED, unknown 1 ML
N Serious injury (AIS ≥ 3) to chest or abdomen Indicator 4 LR
N Serious injury (AIS ≥ 3) to extremity Indicator 7 LR
N Serious injury (AIS ≥ 3) to the head Indicator 1 LR

Abbreviations: AIS, Abbreviated Injury Score; ED, emergency department; GCS, Glasgow Coma Scale; ISS, Injury Severity Score; LR, logistic regression; ML, multinomial logit; PMM, predictive mean modeling; SBP, systolic blood pressure.

a

EMS time is also used as a continuous variable in some analysis models but not in the imputation models.

b

In most instances ISS is missing because one of the individual AIS scores is listed as “not otherwise specified” preventing the calculation of the ISS. However, there are other AIS scores available and this information can be used in the imputation process (see last 5 characteristics).