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Look back for the Charlson Index did not improve risk adjustment of cancer surgical outcomes
Timothy A Dobbins1, Nicola Creighton2, David C Currow2
1National Centre for Epidemiology and Population Health, ANU College of Medicine, Biology and Environment, The Australian National University, Building 62, Mills Road, Canberra ACT 0200, Australia.
Insights
For cancer surgery outcomes, exclude metastatic cancer from the Charlson score for better short-term results. No single implementation was best, and look-back periods offered no advantage.
Area of Science:
- Health Services Research
- Surgical Oncology
- Health Informatics
Background:
- The Charlson score is a widely used comorbidity index.
- Optimal implementation for cancer surgery outcomes using administrative data is under-researched.
- Variations include handling metastatic cancer and look-back periods.
Purpose of the Study:
- To compare four Charlson score implementations for cancer surgery.
- To evaluate impact on hospital risk adjustment models.
- To assess outcomes like mortality, length of stay, and readmission.
Main Methods:
- Utilized linked administrative data from New South Wales, Australia (9 years).
- Identified patients undergoing surgery for colon, rectal, or lung cancer.
- Compared binary outcomes (30/365-day mortality, prolonged stay, readmission) across hospital groups.
Main Results:
- Excluding metastatic cancer improved model performance for short-term outcomes.
- No single Charlson score implementation was consistently optimal.
- Look-back periods reduced patient numbers without enhancing hospital risk adjustment.
Conclusions:
- Charlson scores for hospital risk adjustment in cancer surgery should exclude metastatic cancer.
- No definitive best-performing implementation was identified.
- Incorporating look-back periods provided no discernible benefit.
Objectives:
The Charlson score is a commonly used measure of comorbidity; however, there is little empirical research into the optimal implementation when studying cancer surgery outcomes using administrative data. We compared four alternative Charlson score implementations, including and excluding metastatic cancer and varying the look-back periods.
Study Design And Setting:
Nine years of linked administrative data were used to identify patients undergoing surgery for cancer of the colon, rectum, or lung in New South Wales, Australia. Four binary outcomes of 30- and 365-day mortality, length of stay greater than 21 days, and emergency readmission within 28 days were compared between groups of similar hospitals. Hospital risk adjustment models were compared for alternative Charlson score implementations.
Results:
Excluding metastatic cancer from the Charlson score improved model performance for short-term outcomes, but there was no implementation that was consistently optimal. Incorporating a look-back period reduced the number of patients for analysis but did not improve hospital risk adjustment.
Conclusion:
Charlson scores for hospital risk adjustment of short-term outcomes of cancer surgery should be calculated excluding metastatic cancer as a separate comorbidity. We found no clear best performing implementation and found no benefit in incorporating any look-back period.
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