Low interobserver agreement among expert surgeons using a common morphological classification for pectus excavatum.

Area of Science:

• Thoracic surgery
• Medical imaging
• Surgical outcomes

Background:

• The established visual classification for pectus excavatum, introduced in 2006 and revised in 2013, categorizes deformities into three types.
• Despite its international popularity, concerns regarding the reproducibility of this classification system persist among clinicians.

Purpose of the Study:

• To evaluate the interobserver agreement and reproducibility of the established visual pectus excavatum classification system.
• To assess the impact of objective thoracic indices on classification consistency.

Main Methods:

• A two-stage comparative study involving blinded assessment of standardized pectus excavatum photographs by thoracic surgeons.
• Phase one included six surgeons evaluating 100 cases; phase two involved 17 international experts assessing 10 simplified cases.
• Analysis correlated classification agreement with thoracic indices, including the Titanic Index.

Main Results:

• Complete agreement among surgeons was low (30% in phase one, 6% in phase two).
• High agreement (≥80% observers) was achieved in 49% of cases in phase one.
• Cases with higher agreement showed significantly lower Titanic Index values, suggesting localized deformities correlate with better consistency.

Conclusions:

• Substantial interobserver variability exists in the visual pectus excavatum classification, even among specialists.
• Reliance on surface anatomy alone is insufficient for guiding treatment decisions.
• Quantitative imaging indices, such as the Titanic Index, are recommended to improve reproducibility and clinical decision-making.