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Validation of the “HAMP” Mapping Algorithm: A Tool for Long-Term Trauma Research Studies in the Conversion of AIS 2005 to AIS 98

Adams, Derk BS; Schreuder, Astrid B. PhD; Salottolo, Kristin MPH; Settell, April RN; Goss, J. Richard MD

The Journal of Trauma: Injury, Infection, and Critical Care: July 2011 - Volume 71 - Issue 1 - p 85-89
doi: 10.1097/TA.0b013e3181f9f873
Original Article

Background: There are significant changes in the abbreviated injury scale (AIS) 2005 system, which make it impractical to compare patients coded in AIS version 98 with patients coded in AIS version 2005.

Methods: Harborview Medical Center created a computer algorithm “Harborview AIS Mapping Program (HAMP)” to automatically convert AIS 2005 to AIS 98 injury codes. The mapping was validated using 6 months of double-coded patient injury records from a Level I Trauma Center. HAMP was used to determine how closely individual AIS and injury severity scores (ISS) were converted from AIS 2005 to AIS 98 versions. The kappa statistic was used to measure the agreement between manually determined codes and HAMP-derived codes.

Results: Seven hundred forty-nine patient records were used for validation. For the conversion of AIS codes, the measure of agreement between HAMP and manually determined codes was [kappa] = 0.84 (95% confidence interval, 0.82–0.86). The algorithm errors were smaller in magnitude than the manually determined coding errors. For the conversion of ISS, the agreement between HAMP versus manually determined ISS was [kappa] = 0.81 (95% confidence interval, 0.78–0.84).

Conclusion: The HAMP algorithm successfully converted injuries coded in AIS 2005 to AIS 98. This algorithm will be useful when comparing trauma patient clinical data across populations coded in different versions, especially for longitudinal studies.

From the Quality Improvement Department (D.A., A.B.S., R.G.), Harborview Medical Center, Seattle, Washington; Trauma Research Department (K.S.), Swedish Medical Center, Englewood, Colorado; Trauma Research Department (K.S.), St. Anthony Central Hospital, Denver, Colorado; and Trauma Services Department (A.S.), Swedish Medical Center, Englewood, Colorado.

Submitted for publication March 10, 2010.

Accepted for publication August 30, 2010.

Author Contributions: Mr. Adams and Dr. Schreuder are responsible for the integrity of the data in this study and the accuracy of the data analysis. Mr. Adams, Dr. Schreuder, and Mrs. Salottolo were involved in writing the manuscript. Mrs. Salottolo and Ms. Settell were involved in data selection and data collection. Mr. Adams conceived the study idea. Mrs. Salottolo and Ms. Settell reviewed the manuscript for accuracy.

Address for reprints: Derk Adams, BS, Harborview Medical Center, Box 359731, 325 Ninth Avenue, Seattle, WA 98104; email:

© 2011 Lippincott Williams & Wilkins, Inc.