Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research

Paul A. Fuchs, Deborah J. Del Junco, Erin E. Fox, John B. Holcomb, Mohammad H. Rahbar, Charles A. Wade, Louis H. Alarcon, Karen J. Brasel, Eileen M. Bulger, Mitchell J. Cohen, John G Myers, Peter Muskat, Herb A. Phelan, Martin A. Schreiber, Bryan A. Cotton

Research output: Contribution to journalArticle

2 Citations (Scopus)

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 FASTexamination. 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 FASTexamination 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 FASTexaminations 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.

Original languageEnglish (US)
JournalJournal of Trauma and Acute Care Surgery
Volume75
Issue number1 SUPPL1
DOIs
StatePublished - 2013

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Ultrasonography
Wounds and Injuries
Research
Odds Ratio
Neck Injuries
Abdominal Injuries
Craniocerebral Trauma
Extremities
Translational Medical Research
Retrospective Studies

Keywords

  • FAST examination
  • Imputation
  • MAR
  • MCAR

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine
  • Surgery

Cite this

Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research. / Fuchs, Paul A.; Del Junco, Deborah J.; Fox, Erin E.; Holcomb, John B.; Rahbar, Mohammad H.; Wade, Charles A.; Alarcon, Louis H.; Brasel, Karen J.; Bulger, Eileen M.; Cohen, Mitchell J.; Myers, John G; Muskat, Peter; Phelan, Herb A.; Schreiber, Martin A.; Cotton, Bryan A.

In: Journal of Trauma and Acute Care Surgery, Vol. 75, No. 1 SUPPL1, 2013.

Research output: Contribution to journalArticle

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 2013, 'Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research', Journal of Trauma and Acute Care Surgery, vol. 75, no. 1 SUPPL1. https://doi.org/10.1097/TA.0b013e31828fa51c
Fuchs, Paul A. ; Del Junco, Deborah J. ; Fox, Erin E. ; Holcomb, John B. ; Rahbar, Mohammad H. ; Wade, Charles A. ; Alarcon, Louis H. ; Brasel, Karen J. ; Bulger, Eileen M. ; Cohen, Mitchell J. ; Myers, John G ; Muskat, Peter ; Phelan, Herb A. ; Schreiber, Martin A. ; Cotton, Bryan A. / Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research. In: Journal of Trauma and Acute Care Surgery. 2013 ; Vol. 75, No. 1 SUPPL1.
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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 FASTexamination. 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 FASTexamination 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 FASTexaminations 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.",
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AU - Fuchs, Paul A.

AU - Del Junco, Deborah J.

AU - Fox, Erin E.

AU - Holcomb, John B.

AU - Rahbar, Mohammad H.

AU - Wade, Charles A.

AU - Alarcon, Louis H.

AU - Brasel, Karen J.

AU - Bulger, Eileen M.

AU - Cohen, Mitchell J.

AU - Myers, John G

AU - Muskat, Peter

AU - Phelan, Herb A.

AU - Schreiber, Martin A.

AU - Cotton, Bryan A.

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N2 - 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 FASTexamination. 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 FASTexamination 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 FASTexaminations 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.

AB - 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 FASTexamination. 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 FASTexamination 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 FASTexaminations 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.

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KW - Imputation

KW - MAR

KW - MCAR

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