A Comparison of Three Silver-containing Dressings in the Treatment of Infected, Chronic Wounds
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The time to resolution of infection was less in group 1 (median: group 1 = 2 weeks, group 2 = 4 weeks, group 3 = 4 weeks), and fewer treatments were required to eliminate clinical signs of infection in group 1 (median: group 1 = 6 treatments; group 2 = 12 treatments; group 3 = 12 treatments).
The number of wounds in each of the first 4 weeks that no longer showed clinical signs of local infection is shown in Table 4. The probability of resolving the clinical signs of infection during the course of the study are illustrated in Kaplan-Meier plots (Figure 1).
Complete healing. Time to complete healing was significantly faster in group 1 compared to the other groups (P < 0.05), after adjusting for baseline wound area. Patients in group 1 were nearly 3 times more likely to heal at any time during the study than patients in groups 2 or 3.
Hazard ratios. Group 1:group 2 = 2.74 (P = 0.042; CI: 95% = 1.04–7.27); group 1:group 3 = 2.80 (P = 0.027; CI: 95% = 1.13–6.94).
Time to healing increased significantly with baseline wound area (P = 0.029, hazard ratio = 0.90; P = 0.029; CI: 95% = 0.82–0.99).
The percentage of wounds healed during the study is shown in Figure 2. The number of wounds healed from weeks 5–8 is shown in Table 5. The differences between treatment groups in the probability of healing during the course of the study are illustrated in the Kaplan-Meier plots (Figure 3).
Unwanted effects. During the study, 189 dressing changes were carried out in group 1, 291 in group 2, and 285 in group 3. During dressing changes, unwanted effects were recorded (Table 6). In all dressings, neither pain during dressing changes nor window edema was observed.
The results of this study confirm that silver dressings are effective in eliminating local infection, and therefore, encourage healing. However, there are differences in outcomes.
The authors could not find any published studies that compare different silver dressings in the treatment of chronic wounds in the clinical practice setting. The systematic review by Vermeulen et al11 only found 3 clinical trials comparing products, and only the CONTOP12 study compares, indirectly, other silver dressings, but of unspecified composition. The results of the present study cannot be compared to those of the CONTOP study, since they are methodologically different.
There are some limitations to this study. While the group size may have been small, the sample size for the primary variable (resolution of the clinical signs of infection) was adequate. The study is not statistically powered to detect differences in secondary variables, but where statistically significant differences were detected, they were valid.
The authors debated whether to obtain bacteriological samples, but according to the EWMA documents on wound infection,5,13 bacteriological analysis alone does not establish the presence of infection, and subtle changes in clinical signs of infection are preferred.
Ideally, follow up would have been for at least 6 months, but this is costly and there is usually a high rate of patient attrition over such a long period.
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