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Interobserver and intraobserver variability using the Fuhrman grading system for renal cell carcinoma
Maamoun Al-Aynati1, Vicky Chen, Samih Salama
1Department of Pathology, St Joseph's Hospital, Hamilton Health Sciences Corporation and McMaster University, Hamilton, Ontario.
Archives of Pathology & Laboratory Medicine
|April 24, 2003
Summary
This study found moderate agreement among pathologists grading renal cell carcinoma using the 4-tier Fuhrman system. Simplifying to a 2-tier system significantly improved agreement, highlighting its utility for better diagnostic consistency.
Area of Science:
- Uropathology
- Oncology
- Medical Diagnostics
Background:
- Histologic grading of renal cell carcinoma (RCC) is crucial for prognosis, second only to staging.
- The Fuhrman nuclear grading system, a 4-tier scheme, is widely used in North America for RCC.
- Limited research exists on the interobserver and intraobserver variability of the Fuhrman grading system.
Purpose of the Study:
- To evaluate the interobserver and intraobserver agreement among pathologists using the Fuhrman nuclear grading system for RCC.
- To assess the impact of simplifying the Fuhrman grading system on diagnostic agreement.
Main Methods:
- Four pathologists independently graded 99 primary RCC cases on two separate occasions.
- Slides were stained with hematoxylin-eosin, and grading was performed using the Fuhrman nuclear grading scheme.
- A minimum of 3 months separated the two grading sessions to assess intraobserver variability.
Main Results:
- Moderate intraobserver agreement (mean kappa = 0.45) and low interobserver agreement (combined mean kappa = 0.29) were observed with the 4-grade Fuhrman system.
- When grades were collapsed into a 2-tier system (low vs. high grade), intraobserver agreement improved to substantial (mean kappa = 0.53).
- Interobserver agreement also improved with the 2-tier system (combined mean kappa = 0.45), and 53% of cases showed admixture of two grades.
Conclusions:
- The 4-grade Fuhrman system demonstrates only moderate intraobserver and interobserver agreement in RCC grading.
- Collapsing the Fuhrman grades into a 2-tier system significantly enhances intraobserver agreement.
- A simplified 2-category Fuhrman grading approach is beneficial for improving diagnostic consistency in RCC.