Faculty Collaboration Database

Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research. J Trauma Acute Care Surg 2013 Jul;75(1 Suppl 1):S75-81

Date

08/15/2013

Pubmed ID

23778515

Pubmed Central ID

PMC3744188

DOI

10.1097/TA.0b013e31828fa51c

Scopus ID

2-s2.0-84880414802 (requires institutional sign-in at Scopus site)   3 Citations

Abstract

BACKGROUND: The Focused Assessment with Sonography for Trauma (FAST) examination is an important variable in many retrospective trauma studies. The purpose of this study was to devise an imputation method to overcome missing data for the FAST examination. Owing to variability in patients' injuries and trauma care, these data are unlikely to be missing completely at random, raising concern for validity when analyses exclude patients with missing values.

METHODS: Imputation was conducted under a less restrictive, more plausible missing-at-random assumption. Patients with missing FAST examinations had available data on alternate, clinically relevant elements that were strongly associated with FAST results in complete cases, especially when considered jointly. Subjects with missing data (32.7%) were divided into eight mutually exclusive groups based on selected variables that both described the injury and were associated with missing FAST values. Additional variables were selected within each group to classify missing FAST values as positive or negative, and correct FAST examination classification based on these variables was determined for patients with nonmissing FAST values.

RESULTS: Severe head/neck injury (odds ratio [OR], 2.04), severe extremity injury (OR, 4.03), severe abdominal injury (OR, 1.94), no injury (OR, 1.94), other abdominal injury (OR, 0.47), other head/neck injury (OR, 0.57), and other extremity injury (OR, 0.45) groups had significant ORs for missing data; the other group's OR was not significant (OR, 0.84). All 407 missing FAST values were imputed, with 109 classified as positive. Correct classification of nonmissing FAST results using the alternate variables was 87.2%.

CONCLUSION: Purposeful imputation for missing FAST examinations based on interactions among selected variables assessed by simple stratification may be a useful adjunct to sensitivity analysis in the evaluation of imputation strategies under different missing data mechanisms. This approach has the potential for widespread application in clinical and translational research, and validation is warranted.

Author List

Fuchs PA, del Junco DJ, Fox EE, Holcomb JB, Rahbar MH, Wade CA, Alarcon LH, Brasel KJ, Bulger EM, Cohen MJ, Myers JG, Muskat P, Phelan HA, Schreiber MA, Cotton BA, PROMMTT Study Group

MESH terms used to index this publication - Major topics in bold

Adult
Blood Transfusion
Female
Hemorrhage
Hospital Mortality
Humans
Injury Severity Score
Male
Middle Aged
Predictive Value of Tests
Prospective Studies
Research Design
Resuscitation
Trauma Centers
Treatment Outcome
Ultrasonography
United States
Wounds and Injuries