Inter- and intra-observer (dis)agreement among nurses and doctors to classify colour and exudation of open surgical wounds according to the Red-Yellow-Black scheme


  • Hester Vermeulen MSc, RN,

  • Dirk T Ubbink MD, PhD,

  • Sanne M Schreuder MSc,

  • Maarten J Lubbers MD

Hester Vermeulen
Department of Surgery G4-233 Academic Medical Centre
Meibergdreef 9 PO Box 22700
1100 DE Amsterdam
The Netherlands
Telephone: +31 20 5662767


Aim and objectives.  Primary: to study the level of agreement among nurses and doctors in classifying the colour and exudation of open wounds according to the Red-Yellow-Black scheme. Secondary: to check their agreement with an international expert panel on whether their classification was correct.

Background.  Nurses and doctors classify open wounds to assess systemic and local treatment options. Nowadays, several classification schemes are being used. The Red-Yellow-Black-scheme is commonly used for classifying open wounds or is part of other, more intricate, wound classification models.

Methods.  Eighteen representative photographs of red, yellow and black wounds were presented to 63 nurses and 79 doctors from the Department of Surgery. They classified these open wounds for colour and amount of exudation. Group kappa's (κ) were calculated to assess inter- and intra-observer agreement and their agreement with an expert panel.

Results.  Agreement among the 63 nurses on wound colour (κ = 0·61; 95% CI: 0·49–0·74) and exudation (κ = 0·49; 95% CI: 0·29–0·68) was moderate to good. Agreement among the 79 doctors was similar: κ = 0·61; 95% CI 0·49–0·73 for wound colour and κ = 0·48; 95% CI: 0·36–0·61 for exudation. Nurses’ and doctors’ agreement with the expert panel was also moderate to good: κ-values ranged between 0·48 and 0·77.

Conclusion.  Based on the good to moderate inter-observer agreement as found in this study, the Red-Yellow-Black -scheme appears to be a reliable and accurate classification scheme to assess open (surgical) wounds. Such a scheme may enable nurses and doctors to select the appropriate treatment modalities and evaluate the progress of the healing process.

Relevance to clinical practice.  The Red-Yellow-Black scheme is a helpful tool to classify all kinds of wounds and can be used as stand-alone classification method or as part of wound management concepts.