Inter-observer reproducibility of probing to bone in the diagnosis of diabetic foot osteomyelitis

Aims The objectives of our study were (i) to analyse the inter-observer reproducibility or diagnostic variability of the probing-to-bone test, depending on the training of the professional involved, and (ii) to assess whether the probing-to-bone test can be extrapolated to any professional specialty that deals with these patients. Methods This was a cross-sectional study, involving 75 patients with diabetic foot ulcer and clinical suspicion of osteomyelitis. A registration sheet was completed for all patients involved in the research study, gathering data relative to the results of the probing-to-bone test performed by three observers. Observer 1 was a very experienced professional with several years of experience in the treatment of the diabetic foot; observer 2 was a medium-experienced professional whose experience ranges from 6 to 12 months in the treatment of the diabetic foot; observer 3 was a healthcare professional without experience in the treatment of the diabetic foot. Data were gathered confidentially by a fourth researcher. Results The results showed a kappa index of 0.593 (95% CI0.407-0.778) between observer 1 and observer 2,0.397 (95% CI 0.188-0.604) between observer 1 and observer 3 and 0.53 (95% CI 0.335-0.725) between observer 2 and observer 3. Conclusions The probing-to-bone test demonstrated moderate to fair concordance with an experienced examiner, although the degree of concordance is not significant between groups.