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The impact of subtrochanteric fracture criteria on hip fracture classification
S Y Huang1, C D Grimsrud, J Provus
1Department of Medicine, Kaiser Permanente San Francisco Medical Center, San Francisco, CA, USA.
Insights
Hospital diagnosis codes accurately identify most hip fractures but fail to reliably distinguish subtrochanteric fractures. Radiographic review is essential for accurate subtrochanteric fracture classification in epidemiologic studies.
Area of Science:
- Orthopedics
- Epidemiology
- Health Informatics
Background:
- Hip fractures are a significant public health concern, particularly in older adults.
- Accurate fracture site classification is crucial for epidemiological studies and understanding disease burden.
Purpose of the Study:
- To evaluate the accuracy of coded hospital diagnoses for hip fractures.
- To compare fracture site verification using operative and radiologic data.
- To examine variability in subtrochanteric fracture assignment based on different anatomic criteria.
Main Methods:
- Retrospective study of female hip fracture patients aged 60+ (2007-2008).
- Verification of anatomic fracture site using operative and radiologic records.
- Radiographic image review for subtrochanteric fractures.
- Comparison of two different criteria for subtrochanteric fracture classification.
Main Results:
- International Classification of Diseases, Ninth Revision (ICD-9) coding accuracy exceeded 90% for femoral neck and trochanteric fractures.
- Subtrochanteric fracture coding accuracy was only 26% using Orthopedic Trauma Association (OTA) criteria.
- Broader criteria including the lesser trochanter increased subtrochanteric fracture assignment from 1.3% to 4.2%.
Conclusions:
- Hospital diagnosis codes are insufficient for accurate subtrochanteric fracture identification in epidemiologic research.
- Radiographic image review using established criteria (e.g., OTA) is necessary for precise subtrochanteric fracture classification.
- Accurate classification of subtrochanteric fractures is vital for understanding their unique epidemiology.
Summary:
Hospital diagnosis codes are useful for assessing hip fracture rates in large populations. However, these codes do not reliably differentiate hip fractures that occur in the subtrochanteric region. Identification of subtrochanteric fractures requires review of radiographic images to distinguish these fractures from the more commonly occurring trochanteric fractures.
Purpose:
This study examines the accuracy of coded hospital diagnoses for hip fracture compared to fracture site verification based on operative and radiologic data. The variability in subtrochanteric fracture assignment was also examined using different anatomic criteria.
Methods:
This retrospective study includes female members of Kaiser Permanente Northern California age 60 years and older with nontraumatic hip fracture during 2007-2008. Anatomic site was verified by operative and radiologic records, including radiographic image review for fractures occurring in the subtrochanteric region. Two different criteria were compared for subtrochanteric fracture.
Results:
We identified 2,824 women with incident hip fracture during the 2-year period. The average age was 82.9 ± 8.2 years and 15% were non-White. International Classification of Diseases, Ninth Revision (ICD-9) coding was accurate for femoral neck and trochanteric fractures (>90% confirmed by operative/radiologic reports), compared to only 26% for subtrochanteric fractures using the Orthopedic Trauma Association (OTA) criteria for subtrochanteric fracture. Using OTA classification, 1.3% of hip fractures were assigned as subtrochanteric compared to 4.2% when the criteria were broadened to include the lesser trochanter. Both femoral neck and pertrochanteric fracture rates increased exponentially with age, while age-related rates in subtrochanteric fracture differed by diagnostic classification method; the broader criteria including the lesser trochanter produced age-related trends that mirrored femoral neck and pertrochanteric fractures.
Conclusion:
Unlike femoral neck and pertrochanteric fractures, epidemiologic studies of subtrochanteric fractures cannot rely on ICD-9 codes alone. Review of radiologic images using OTA criteria is required for identification of subtrochanteric fractures occurring below the lesser trochanter.