Fifteen studies met the inclusion criteria. These included 985 patients (range 32 to 124) and 1,056 chronic wounds. Eight studies were prospective. Six studies had a quality level of 1 to 3 and nine had a level of 4 or 5.
The overall prevalence of infection of chronic wounds was 53% (95% CI, 40% to 67%, I2=95%) and 45% (95% CI 32% to 58%, I2=82%) in the level 1 to 3 studies and 59% (95% CI 40% to 76%, I2= 97%) in the level 4 and 5 studies.
This abstract presents the results when tests were compared to the gold standard of tissue biopsy culture; further results were reported where reference standards other than tissue biopsy culture were reported.
An increase in the level of pain was considered to make infection more likely (likelihood ratio range 11 to 20; two studies). The absence of increasing pain, purulent exudate, erythema, heat, oedema or foul odour (one or two studies each) were not reliable for diagnosing wound infection. Wounds that had no serous exudates (LR range 0.57 to 0.62) or were healing rapidly (LR range 0.29 to 0.96) were less likely to be infected.
The signs recommended by the Infectious Diseases Society of America for identifying diabetic foot ulcer infections (one study) had a sensitivity of 52% and specificity of 46% (LR+ 0.96, 95% CI 0.60 to 1.6 and LR- 1.0, 95% CI 0.61 to 1.8).
A positive swab culture (one study) using the Levine technique was helpful in predicting wound infection (LR+ 6.3, 95% CI 2.5 to 15), but those that used the Z-technique or wound exudate or the inflammatory marker IL-6 (one study) were not.