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Inter-rater reliability and annual rescoring of the Charlson comorbidity index
Judith Bernardini1, Susan Callen, Linda Fried
1University of Pittsburgh Pennsylvania, USA. bernardini@pitt.edu
Insights
The Charlson Comorbidity Index (CCI) is a reliable tool for assessing comorbidity in peritoneal dialysis patients. Initial scoring is reproducible, but annual rescoring does not improve survival prediction.
Area of Science:
- Nephrology
- Clinical Epidemiology
Background:
- Comorbidity assessment in dialysis patients is crucial for predicting outcomes.
- The Charlson Comorbidity Index (CCI) is a widely used comorbidity measure.
- Reproducibility and ease of acquisition are key for clinical utility.
Purpose of the Study:
- To determine the inter-rater reliability of the CCI in peritoneal dialysis (PD) patients.
- To evaluate the utility of annual CCI rescoring for predicting patient survival.
Main Methods:
- 100 consecutive PD patients were included.
- Two nurses independently scored CCI at PD initiation.
- One nurse rescored CCI annually.
- Patient survival data was collected.
- Kappa scores and time-dependent analyses were used.
Main Results:
- High inter-rater reliability for initial CCI scoring (kappa = 0.93).
- Average CCI scores were 5.2 and 5.3.
- Annual CCI rescoring did not enhance survival prediction.
- Average CCI decreased over time due to mortality.
Conclusions:
- The CCI is a reliable and easily applicable tool for assessing comorbidity in PD patients.
- Initial CCI scoring at dialysis start is recommended.
- Annual CCI rescoring offers limited benefit for survival prediction in this cohort.
Abstract:
A measure of comorbidity in dialysis patients must not only predict outcomes but also be reproducible and easy to obtain. Our primary purpose in the present study was to determine the inter-rater reliability of the Charlson comorbidity index (CCI) in peritoneal dialysis (PD) patients. Our secondary purpose was to evaluate the usefulness of annual rescoring of the CCI as a predictor of patient survival. We included in the study 100 consecutive patients (mean age: 52 +/- 16 years; 85% white; 39% with diabetes) who started PD between 1995 and 2000 at a single center: Two nurses independently scored the CCI at the start of PD. One nurse rescored each patient on the yearly anniversary of the start of PD. Patient survival was recorded for each year Kappa score and time-dependent analysis were applied. The kappa score between the two CCI scores at the start of dialysis was 0.93. (The average scores by the two nurses were 5.2 and 5.3.) Annual rescoring of the CCI demonstrated no increase in its predictive value regarding patient survival. However, given the minimal change in the CCI for the patient population in the present study, that question needs further study. Over time, the average CCI fell--an unsurprising result, because patients with higher CCI scores at the start of dialysis are the most likely to die. We conclude that the CCI is a reliable and easily applied tool for assessing comorbidity. Dialysis units should consider obtaining this measure at the start of dialysis in all patients. Repetitive annual scoring was not helpful in improving prediction of survival.
