Introduction

Globally, the prevalence of diabetes is estimated to be approximately 10% of the adult population [1]. Studies suggest that 2.5% of patients with diabetes develop diabetic foot ulcers (DFUs) each year and a staggering 25% develop diabetic foot ulcers at some point in their lifetime [2, 3]. If not managed promptly, it leads to infection and sepsis, which later on may necessitate a limb amputation [4, 5]. Infected diabetic wounds are responsible for 84% of all non-traumatic amputations in patients with diabetes mellitus [6]. Dressing remains the mainstay of management of DFU aided by antibiotics and debridement as and when needed. Currently, negative-pressure wound therapy/vacuum-assisted closure (VAC), foam dressing, and conventional dressing are three common modalities of management available.

We have not come across any Indian study that compares the outcome of these three treatment methods in a comprehensive way. Our study was aimed at comparing these modalities of treatment with regard to healing rate, duration of hospitalization, need for secondary procedures, and cost of treatment.

Materials and methods

The study was designed and conducted as a single-center, prospective study between January 2018 and December 2021. Written informed consent was obtained from all the patients who participated in the study. Patients’ data were kept confidential, and they were given full freedom to leave the study at any point in time.

Patients more than 18 years of age, admitted with a diabetic foot ulcer, were included in the study. Patients with coagulopathy, peripheral arterial/venous disease, ulcer with the underlying osteomyelitis, connective tissue disorders, sickle cell disease, diseases with a poor prognosis (including malignant tumors), treatment with corticosteroids or immunosuppressive agents, and severe malnutrition (serum albumin G3.0 g/dL), treated with biological or biochemical therapy, including growth factors or cells, were excluded from the study. Also, patients with ulcers with Wagner’s [7] grade I, III, IV, and V and bilateral involvement were excluded from the study.

Of the 95 patients included in the study initially, 5 dropped off the study due to COVID-19 infection–related illness. The remaining 90 were finally enrolled in the study. Patients were randomized into 3 groups (30 patients in each group) using the random table generated using Microsoft XL. Group 1 patients were treated with standard saline gauge dressing, group 2 patients were treated with a hydrophilic foam dressing, and group 3 patients were treated with VAC dressing.

A complete medical history was obtained at the time of admission. General blood tests including complete blood counts, blood glucose, liver, and renal profile and inflammatory markers were performed. Status of the wound including size, grade, presence of slough or debris, and depth of the wound were recorded on admission. To evaluate the vascularity of the diabetic foot, transcutaneous partial oxygen tension (tcpO2) and Doppler wave were measured.

Peripheral pulses were not well felt in all cases. However, SPO2 of the toes was documented in all cases. And in patients where SPO2 was not measurable, these cases were excluded. A wound swab for culture sensitivity was sent for all patients as a routine. Whenever necessary, intravenously administered antibiotics were administered empirically, and they were changed according to the results of culture and sensitivity tests. Initial surgical debridement was carried out as standard for all patients at the bedside or in the operating room, as per the wound condition. Proper glycemic control of all patients was ensured. Appropriate off-loading was provided according to the location of the ulcer. Debridement was done if the infection was deemed to be spreading.

Method of dressing

In group 1, the daily dressing of the patient was done with a normal saline-soaked gauge [8] after thorough cleaning of the wound. The wound was examined for slough or debris and cleaned with hydrogen peroxide if needed. Saline-soaked gauge piece was placed over the wound, covered with 2 layers of dry gauge, and then secured with a micropore/roller gauge dressing.

In group 2, the dressing was changed every third day with hydrophilic foam [9] with 2 layers of dry gauge on top of it, after thorough cleaning of the wound with hydrogen peroxide if needed.

In group 3, VAC [10] was used with − 125 mm hg of continuous pressure sessions. The wound was cleaned with normal saline or hydrogen peroxide as indicated and VAC was reapplied every 5th day.

Patients’ wounds were monitored until complete re-epithelization or complete healing (defined as 100% healthy granulation and wound fit for split skin grafting) was achieved. The outcome of the three different modalities was assessed and compared with respect to healing rates, duration of hospital stays, the number of debridement done, need for the secondary procedures, and mean cost of treatment. Statistical analyses were performed using MedCalc for Windows, version 19.1.7 (MedCalc Software, Ostend, Belgium).

Results

The demographics of the patients participating in the study are shown in Table 1. There was no significant difference between the average age or proportion with regard to gender among the three groups (Table 1). There was no significant difference in the duration of diabetes among the three groups (p = 0.7195). There was no significant difference in ulcer size among the three groups (p = 0.6427) (Table 1). The majority of the ulcers were located on the lateral malleolus in the conventional and foam group and were located on the dorsum of the foot in the VAC group (Table 2). About 6.67%, 3.33%, and 6.67% of the cases among conventional, foam, and VAC groups, respectively, did not have a digital pulse.

Table 1 Demographics of patient in the study
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Table 2 Location of wound amongst the patients
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The mean hospital stay of the study subjects was 31.17 days, 24.13 days, and 15.17 days among the conventional dressing group, foam dressing group, and VAC dressing group, respectively in the present study (Table 3 and Fig. 1). There was a statistically significant difference in the hospital stay among the three groups (p < 0.001) with the least stay in the VAC group.

Table 3 Comparison of results of the study
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Fig. 1
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Correlation of healing time and surface area among different groups

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The mean number of debridements in the study subjects was significantly low in the VAC group compared to the other two groups (Table 3). No significant difference was noted between conventional dressing and foam dressing groups. About 30.00% in the conventional dressing group, 30.00% in the foam dressing group, and 43.33% of the cases in the VAC group underwent secondary procedures like a local flap or split skin graft (Table 3). The healing rates among conventional, foam and VAC groups were 90%, 93.33%, and 93.33%, respectively, with no significant difference between the three groups. The rate of amputation among the three groups was also insignificant (Table 3). The mean cost of the treatment of the study subjects was 3076.67 INR, 3717.33 INR, and 10,680 INR among the conventional dressing group, foam dressing group, and VAC dressing group, respectively, in the present study (p < 0.001) with VAC costing almost thrice than that the other two groups.

Discussion

The current concept of an “ideal wound dressing” is the one that removes excess exudate, maintains a moist environment, protects against contaminants, causes no trauma on removal, leaves no debris in the wound bed, relieves pain, provides thermal insulation, induces no allergic reactions, and should be cost-effective [11, 12]. Normal saline dressing, hydrophilic foam dressing, and vacuum-assisted closure are the 3 modalities of dressing being used most commonly these days, and our study aimed at comprehensively comparing these in terms of duration of treatment, number of debridements, or secondary procedure needed, final outcome, and cost of treatment.

In our study, the mean age and proportion regarding the gender of the patient were comparable among the groups. There was no difference in the average size and grade of the wound between the 3 groups. The duration of diabetes in the 3 groups was also comparable. The majority of the wounds were located over the lateral malleolus and dorsum of the foot.

When comparing the duration of treatment in terms of period of hospitalization, it was found in our study that VAC was the most effective with the least mean hospital stay (15.17 ± 3.53 days), followed by hydrophilic foam dressing (24.13 ± 6.23 days). Normal saline dressing had the maximum duration of treatment (31.17 ± 5.93 days) and was significantly more than the other 2 groups. Armstrong and Lavery [13] in their study have stated median time to closure in VAC group was 56 days opposed to 77 days in conventional saline dressing group. Vaidhya et al. [14] in an Indian study with sixty patients with DFU showed a mean time to healing of 17.2 days in VAC group compared to 34.9 days in normal saline dressing group. Blume et al. [15] had found that major proportion of patient receiving VAC therapy achieved complete skin closure or 100% reepithelization. Etoz A. et al. [16] found mean time to complete wound closure of 11.25 days in VAC group compared to 15.75 days in conventional dressing group. Roberts et al. [17] in their study comparing hydrophilic foam dressing and saline-soaked dressings in diabetic foot ulcers showed that time to healing was comparable in the two groups. Liu et al. [18] in their study also showed that VAC significantly reduces DFUs compared to standard dressing.

The mean number of debridement needed was significantly less in the VAC group (1.6 ± 0.72) compared to the other 2 groups (2.31 ± 0.52 in foam dressing and 2.37 ± 0.61 in saline dressing). But there was no difference in outcome and rate of need for secondary procedures among the 3 groups in our study. In a study by Nather et al. [6] on 11 patients followed over the course of VAC therapy, healing was achieved in all wounds. Nine wounds were covered by split-skin grafting and two by secondary closure.

Although few studies have shown VAC to reduce the need for reamputations, there was no direct correlation of reamputations with VAC in our study [19]. Sepúlveda et al. in their study also did not find any significant difference with regard to amputations among patients treated with VAC [20]. Armstrong et al. [13] found a 90.3% limb salvage rate without amputation in a study on the effects of VAC on 31 subjects. In an 11-patient study by Nather et al., 100% limb salvage was achieved.

The average cost of VAC treatment was INR 10,680 (140 USD) per hospitalization, which was significantly higher than normal saline dressing (INR 3076/ 40 USD) and hydrophilic foam dressing (INR 3717/ 48 USD) in our study. The cost of VAC is its greatest limitation currently, especially in developing countries.

A review of literature on management of diabetic foot ulcer is shown in Table 4. In our search of literature, we have not come across any Indian study that compares all the three forms of dressing in a comprehensive manner.

Table 4 A review of literature on management of diabetic foot ulcers
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The limitation to our study is that there may be a bias because our study center hospital is a tertiary referral center for complex diabetic foot ulcers. Therefore, the outcomes of our study might not be applicable to small hospitals or primary care centers.

Conclusion

There is no difference in ultimate healing among the three groups, but with VAC there is early healing and a decrease in the hospital stay. However, looking at the cost, foam dressing is a good option with a good healing rate as compared to conventional dressing, and lower costs as compared to VAC dressing.