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INTRODUCTION
Stoma formation has been used widely to prevent disastrous complications due to anastomotic leakage after proctectomy or emergency bowel resection. A patient with a temporary stoma may undergo stoma reversal surgery several months after the initial surgery where possible. However, stoma reversal surgery is associated with various complications of abdominal surgeries. The most common of these is surgical site infection (SSI), with an incidence as high as 40% [12]. Therefore, many surgeons have used purse-string skin closure (PSC) rather than linear primary closure (LPC) to reduce the rate of SSI. Indeed, 2 systematic reviews and meta-analyses revealed that PSC is associated with a significantly lower risk of SSI than LPC [23].
In the PSC procedure, a small hole for discharge drainage is formed at the center of the purse-string wound. Therefore, this method carries a disadvantage in that the wound healing period is prolonged because the wound heals by secondary intention. A randomized controlled trial (RCT) that compared PSC with LPC revealed that the wound healing period in the PSC group was prolonged approximately 2-fold compared with that in the LPC group if SSI did not occur [4].
Recently, negative-pressure wound therapy (NPWT) has been applied to laparotomy surgical wounds to reduce wound complications, and the reported results were encouraging [56]. NPWT can be applied not only to reduce the SSI rate but also to promote wound healing. A Cochrane review revealed that NPWT application reduces the wound healing period in the treatment of diabetic foot [7]. After reviewing the previously published literature, we hypothesized that the application of NPWT for PSC wounds would reduce the wound healing period.
Therefore, this randomized controlled study aimed to evaluate the efficacy of NPWT in reducing the wound healing period for PSC of skin closure after stoma reversal.
METHODS
Trial design, ethics, and registration
This study was an RCT conducted according to the Consolidated Standards of Reporting Trials (CONSORT) statement [8] and in accordance with the ethical standards of the Declaration of Helsinki. This trial was approved by the Institutional Review Board of Yeungnam University Medical Center on June 12, 2019 (No. 2019-04-031-002). Written informed consent was obtained from the patient for the publication of this study including all clinical images. The study was registered with the Clinical Research Information Service in June 2019 (KCT0004063), and the study protocol was published in 2020 [9].
Participants
Patients aged >20 years who had undergone stoma reversal surgery between June 2019 and May 2021 at our institution and agreed to participate in this study were enrolled. Patients with skin diseases such as allergies were excluded, as these conditions can interfere with the application of general dressing materials. Patients with an American Society of Anesthesiology physical status grade of ≥III or who were unable to express themselves due to dementia, mental retardation, or other mental conditions were excluded. All participants were randomly assigned to either the control or intervention group at a 1:1 ratio after all surgical procedures were performed using a computerized randomization system. To ensure randomization, random numbers were generated and assigned to each patient’s screening number. The treatment methods were then allocated based on the arrangement of these random numbers in random order.
Interventions
Prophylactic antibiotics (2nd generation cephalosporin) were administered 1 hour before surgery. All stoma reversal surgeries were performed under general anesthesia by experienced colorectal surgeons using standard techniques. Bowel anastomosis was performed using stapled or hand-sewn sutures at the discretion of the surgeon. Facia closure at the stoma site was performed using absorbable suture interruptedly (1-0 Vicryl, Ethicon), and skin closure was performed by PSC method using absorbable monofilament suture material (2-0 Monocryl, Ethicon), leaving a central opening of 0.5 cm or less as possible. Subsequently, the patients were assigned to either the control or intervention group. If the patient was assigned to the control group, a simple transparent waterproof dressing (Allevin, Smith & Nephew Health Care) was applied, whereas a portable NPWT device, PICO (Smith & Nephew Healthcare) dressing was applied to the intervention group (Fig. 1).
In the control group, routine dressing changes were performed once a day, while in the intervention group, dressing changes occurred twice a week. Additional dressing changes were administered as needed during the postoperative hospital stay, especially when the dressing material became wet with discharge. In the intervention group, if patients required dressing changes more than once a day during hospitalization, a switch from NPWT (PICO) dressings to conventional (Allevin) dressings was planned to address cost-effectiveness concerns.
Following discharge, outpatient follow-up appointments were scheduled twice a week until wound healing was deemed complete. After confirming the complete healing of the wound, the dressing was subsequently discontinued.
Endpoints
The primary endpoint of this study was the wound healing period. Complete wound healing was defined as near-complete epithelialization of the wound without discharge or SSI (Fig. 2). It was determined by agreement between a single wound/ostomy specialist nurse and surgeons.
The secondary endpoints comprised various parameters, which encompassed the following: the SSI rate in accordance with the Center for Disease Control definition [10], the length of postoperative hospital stay, the quantity of wound dressings (encompassing dressing during the postoperative hospital stay, self-administered or administered by medical staff after discharge), the frequency of hospital visits for wound dressing, and the comprehensive cost of the dressings. The patient and observer scar assessment scale (POSAS) was also evaluated approximately one month after surgery [11].
Sample size calculation and statistical analysis
The sample size calculation was based on a previous RCT, which revealed a wound healing period approximately 2 times longer in the PSC group than in the conventional linear closure group when SSI did not occur [4]. As a superior design to achieve 80% power at the 5% (2-sided) level of significance to detect 7 days of reduction in the wound healing period, 36 participants were required to allow for 10% attrition.
Normally distributed data was examined using the Student t-test, and nonnormally distributed data were analyzed using the Mann-Whitney U-test. The chi-square or Fisher exact tests were used to examine categorical variables. Statistical significance was declared for tests with P < 0.05.
RESULTS
A total of 47 patients underwent stoma reversal surgery at our institution during the study period. Among these, 36 patients were included in the study after excluding 11 patients. Immediately following discharge, 2 patients in the control group were lost to follow up. Therefore, a total of 34 patients were included in the final analysis. A CONSORT diagram of the study is shown in Fig. 3. The baseline characteristics such as sex, age, body mass index, and stoma type did not differ between the groups (Table 1).
The median wound healing period was significantly shorter in the intervention group than that in the control group (17.5 days [range, 11–24 days] vs. 21.5 days [range, 14–41 days], P = 0.006) (Fig. 4). SSI rate and hospital stay did not differ between the 2 groups. However, the median number of dressings was lower in the experimental group than in the control group (5 [range, 3–7] vs. 17 [range, 10–30], P < 0.001), although the median number of hospital visits for wound dressing did not different between the 2 groups (2 [range, 1–4] vs. 2 [range, 1–8], P = 0.303). The median of total cost for dressing did not differ between the 2 groups (NPWT vs. control: $155.64 [range,$88.94–$266.82] vs. $181.09 [range, $108.66–$253.53], P = 0.365). The POSAS scores did not differ between the 2 groups. The comparison results for the secondary endpoints are presented in Table 2.
DISCUSSION
SSI is the most common complication of stoma wound closures. The PSC method, therefore, has been applied for stoma closure to reduce SSI; however, it is problematic in that the wound healing period is prolonged.
NPWT has been used for promoting wound healing as well as for reducing SSI. Numerous studies have demonstrated the efficacy of NPWT applied to various wounds, such as diabetic foot ulcers, pressure sores, and laparotomy wounds [5712]. The mechanism of NPWT’s promotion of wound healing can be explained by increasing the expression level of cytokines and growth factors in wounds, accelerating angiogenesis, and reducing seroma formation [2131415]. Therefore, in this study, we attempted to resolve the delayed wound healing of PSC closure for stoma reversal wounds without increasing the SSI rate by applying NPWT.
The primary outcome of this study was the wound healing period, and the results of this study revealed a significant reduction in the wound healing period in the NPWT group compared to the control group, with no differences in the SSI rate between the 2 groups. Although there was no difference in the wound healing time between PSC and LPC according to a previous meta-analysis [16], this reflected the high SSI rate that delays wound healing in the conventional linear closure group. Indeed, results from an RCT included in the meta-analysis revealed that the wound healing time in patients without SSI in the PSC group was approximately 2 times that of the LPC group [4]. Therefore, it can be said that our results are meaningful in that the wound healing period was significantly reduced under similar SSI rates. A recent RCT similar to our study design revealed a higher complete wound healing rate in the NPWT group, although there was no significant difference [17]. The difference between that study and the present study is that we compared the wound healing time instead of the proportion of complete wound healing 30 days after surgery.
Other papers stating that NPWT is cost-effective exist; however, they focus on cost savings because of reducing the SSI rate by applying NPWT to the wound [518]. In the present study, we compared the total cost of wound dressing and concluded that there was no significant difference in the total cost between groups. However, this result was due to the differences in the total number of wound dressings performed, which was significantly lower in the NPWT group than in the control group, although the cost of NPWT was higher than that of simple dressing material. In cases of NPWT, frequent dressings were not required because early seroma oozing did not occur. This may have been due to the vaporization of the absorbed fluid of the NPWT material. Therefore, wound dressing could be performed twice a week, as planned, in most patients in the NPWT group. However, in the control group, dressing changes were more frequent than planned because of fluid oozing out of the dressing materials. In addition, the NPWT group exhibited a shorter wound healing time compared to the control group. This accelerated healing process not only resulted in a decreased need for dressings but also contributed to cost reduction, even though the postoperative hospital stay and SSI rate were comparable between the 2 groups. A recent study reported that PICO dressing required fewer visits to the community nurse, which is consistent with our results in terms of reducing the number of wound care visits [19].
In terms of aesthetic satisfaction, PSC has been shown to have better outcomes than LPC according to previous studies [42021]. However, few studies have evaluated the aesthetic satisfaction between NPWT and conventional dressings after PSC. To our knowledge, one previous RCT revealed results comparable to ours regarding the aesthetic evaluation of patients [17]. However, they compared the aesthetic evaluation on postoperative day 7 with a visible analog scale, whereas we investigated aesthetic satisfaction using POSAS approximately 30 days after the operation, and most of the wounds were complete for objective and precise data collection, and our results regarding the POSAS did not differ between the 2 groups.
The main limitation of the present study was its small sample size, which limited subgroup analysis, such as distinguishing loop ileostomy and end colostomy. Second, although the wound healing period was significantly different between the 2 groups, the difference of about 4 days may not affect real clinical practice. Nevertheless, we believe that reducing the total number of wound dressings without increasing the SSI rate and cost can have a greater impact on clinical practice. Third, we did not investigate long-term results, such as incisional hernia or enterocutaneous fistula related to stoma closure. The long-term outcomes should be validated in further studies.
In conclusion, this study revealed that NPWT application after PSC for stoma reversal site closure was effective in reducing the wound healing period compared to simple dressing without increasing SSI and cost.
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