Reliability and validity of pressure ulcer diagnosis and grading: an image-based survey

The reliability and validity of pressure ulcer diagnosis and grading are major methodological issues in studies and reports on pressure ulcer frequency.

The aim of the study was to estimate the reliability and validity of pressure ulcer diagnosis and grading within the interdisciplinary pressure ulcer project of the University Clinics of Essen, Germany.

Fifty images of wounds from the foot/heel region and 50 images of wounds from the buttock/hip region were classified using a 4-grade scale. A gold standard was established by consensus of two senior physicians.

The images were assessed PC-based, independently by each rater.

Five nursing experts and two physicians participated.

Mean simple Kappa and per cent agreement were calculated to assess reliability and validity.

Mean simple Kappa values showed a moderate interrater agreement for grading and a fair interrater agreement for diagnosis. The percentage of agreements was highest for pressure ulcer diagnosis in the buttock/hip region with 90.5% and lowest for pressure ulcer grading in the buttock/hip region with 63.5%. No differences could be found between nurses and physicians.

The differentiation between pressure ulcers and other skin lesions is rather difficult. It is important to assign the lower grade when the available information does not definitely support the higher grade. The level of agreement found was intermediate in the range of published results. A substantial level of agreement should be obtainable through further standardisation and training. Future studies should control for dependency in the assessment situation and dispense with the category "uncertain".