Validity of diagnosis of superficial infection of laparotomy wounds using digital photography: Inter- and intra-observer agreement among surgeons

Background. The use of digital photography to assess and document the wound healing process has become increasingly popular. One of the most common complications of wound healing is infection, but the validity of digital photography for the diagnosis of wound infection is unknown. We intended to measure the degree of inter and intra-observer agreement on the diagnosis of superficial wound infection using digital photography. Methods. In a prospective, observational clinical study, abdominal wounds were photographed daily and signs of infection were documented in a standard manner. Four surgeons independently assessed photographs of 50 wounds opened for infection within hours after photography and 50 normally healed wounds (n = 50). Wound pain scores, morning temperature, and postoperative day were noted. Surgeons recorded the presence of infection and treatment for each wound. Paired kappa (κ) values were calculated and intra-observer agreement was measured after 4-6 weeks. Results. Mean specificity with regard to infection was 97% (94%g-100%) and mean sensitivity was 42% (32%-48%). Paired κ-values with regard to wound infection were: 0.54, 0.67, 0.68, 0.63, 0.58, and 0.61. Agreement on treatment was present in 76 of 100 wounds (κ values: 0.15, 0.17, 0.20, 0.72, 0.63, 0.68). Kappa values for intra-observer agreement on infection were: 0.66, 0.43, 0.74, and 0.76 for surgeons A, B, C, and D, respectively. Conclusion. Inter- and intra-observer agreement on the diagnosis of superficial infection with digital photography are moderate, but specificity is high. Physical examination findings should also be reported.