Digital imaging versus conventional contact tracing for the objective measurement of venous leg ulcers

This study aimed to compare the accuracy and inter-observer reproducibility of leg ulcer measurements made using digital images and conventional contact tracing.

The accuracy of measurements made with these two methods by four observers of 11 shapes with a known area was assessed. The time taken to do this was also measured. Following this, the accuracy and inter-observer reproducibility of the two methods was measured for patients with leg ulcers presenting to the vascular clinic, with contact tracing as the reference.

For the reference shapes, both methods had a mean error of less than 5%. Contact tracing significantly underestimated the area by 3.9% (p < 0.05), while digital tracing showed no significant error. Digital tracing was quicker than contact tracing, especially for larger shapes (p < 0.05). For leg ulcers, there was no significant difference between area measurements made by the two methods. Inter-observer variation of digital tracing was greater for the ulcers than the reference shapes. This was due to differences in subjective interpretation and technical problems in recording some images.

Measurement of leg ulcer area using computer-aided tracing of digital camera images is more accurate and quicker than contact tracing provided that appropriate care is taken when taking the pictures. Digital images offer considerable advantages in the shared hospital-community care of patients with leg ulcers.