Learning curve and interobserver reproducibility evaluation of liver stiffness measurement by transient elastography.

BACKGROUND/AIMS: Fibroscan allows liver stiffness examination (LSE) that is well correlated with fibrosis stages. Our main objective was to evaluate LSE learning curve.

METHODS

LSE results of five novice observers with different medical status were compared with those of five expert observers (physicians with >100 examinations) in 250 patients with chronic liver disease. Each novice-expert pair had to blindly examine 50 consecutive patients divided into five consecutive subgroups of 10 patients.

RESULTS

In each observer group, novice-expert agreement [intraclass correlation coefficient (Ric)] for LSE results was excellent from the first to the last subgroup. Novice-expert agreement for LSE results varied with liver stiffness level: <9 kPa: Ric=0.49; >or=9 kPa: Ric=0.87. Relative difference (%) between novice and expert LSE results was independently associated with the number of valid LSE measurements, and stabilizes around 20-30% after the fourth valid measurement. In each observer group, novice-expert agreement (Ric) for LSE success rate progressively increased as a function of time.

CONCLUSION

LSE requires no learning curve: a novice is able to obtain a reliable result after a single training session, whatever the professional status. However, success rate will progressively increase. An LSE with less than four valid measurements should not be considered as reliable.