Comparison of “Semiocclusive Dressing” Treatment Using Plastic Wrap or Low-Adherent Absorbent Wound Dressings Versus Occlusive Dressing Treatment for Stage II Pressure Injuries: A Randomized,Controlled,Noninferiority Trial

Abstract

Objective:

To verify the noninferiority of the effectiveness of “semiocclusive dressing” (SOD) treatment using plastic wrap or low-adherent absorbent wound dressings compared with occlusive dressing (OD) treatment for National Pressure Injury Advisory Panel stage II pressure injuries.

Approach:

This 12-week, open-label, randomized, controlled, noninferiority trial was conducted at one hospital and three care facilities. Of the 115 participants, 56 were assigned to SOD treatment and 59 to OD treatment. The study design adhered to the CONSORT 2010 extension statement for noninferiority trials. The primary outcome was a comparison of the healing times for both treatments, with the noninferiority margin set at 7.0 days. Secondary outcomes included treatment costs, Kaplan–Meier curves, and incidence of adverse events.

Results:

The mean healing times for SOD and OD treatments were 19.7 and 22.5 days, respectively (p = 0.4175). The 95% confidence interval of the difference was –4.0 to 9.6. Since its lower limit was within the noninferiority margin, SOD treatment was confirmed to be not significantly worse than OD treatment. OD treatment had a significantly higher mean cost than SOD treatment (p < 0.0001). Kaplan–Meier curves for both groups were similar (p = 0.249). The incidence of adverse events in both groups was comparable.

Innovation:

Uniquely, the SOD does not tightly adhere to or completely occlude the wound and can manage abundant exudate. Therefore, SOD treatment maintains an adequately moist environment to facilitate wound healing.

Conclusion:

SOD treatment was more cost-effective than OD treatment for stage II pressure injuries.

Graphical Abstract

Jun Takahashi, MD

Keywords

noninferiority trial plastic wrap pressure injury pressure ulcer randomized controlled trial semiocclusive dressing

INTRODUCTION

Occlusive dressing (OD) treatment using advanced dressing materials is a key component in the management of pressure injuries.¹ This is a standard treatment for all stages of pressure injuries,^1–4 as defined by the National Pressure Injury/Ulcer Advisory Panel (NPIAP) classification.^5,6 In particular, OD treatment is effective for wounds with minimal exudate, including NPIAP stage II (superficial partial-thickness wounds with exposed dermis) and stage III pressure injuries (full-thickness wounds reaching the adipose tissue) in the proliferative phase. However, ODs have limitations in treating deep wounds with abundant exudate and necrotic tissue, including stage III and stage IV pressure injuries (full-thickness wounds reaching the muscle layer) in the inflammatory phase. ODs seal the wound and absorb exudate, but manage only a limited amount; thus, excess exudate may increase intrawound pressure and worsen the wound. In addition, multiple types of dressings (e.g., hydrocolloid, foam, gel, alginate, and silver-containing dressings) must be stocked, as the appropriate choice depends on factors such as the wound stage, amount of exudate, condition of granulation tissue, and presence of infection. However, maintaining such a variety of dressings is often difficult in facilities that do not specialize in wound care, such as nursing homes and geriatric hospitals. Other than ODs, although the guidelines state that treatments, including negative-pressure wound therapy, ultrasound therapy, electrical stimulation, and growth factors, are effective,^1–4 they are impractical in many facilities because of the requirement for special equipment, high costs, and complex procedures. Therefore, the development of more cost-effective and practical next-generation treatments is imperative.

Semiocclusive dressing (SOD) treatment offers a versatile option to meet various treatment needs, although it is not widely known or adopted worldwide. SOD treatment for pressure injuries involves using plastic wrap or low-adherent absorbent dressings to occlude incompletely the wound.⁷ SODs do not tightly adhere to or seal the wound and allow exudate to flow out of the wound. The dressings are secured with weakly adhesive nonwoven or plastic tape, allowing partial detachment when abundant exudate is produced, thereby preventing increased intrawound pressure and wound deterioration. Thus, SOD treatment maintains a moist wound environment to promote healing and remove devitalized tissue through autolytic debridement.^7,8 Since the wound is not sealed, the lack of air permeability does not pose issues.

The first SOD method was plastic wrap dressing (PWD) treatment, whose clinical benefits have been reported.^8–10 However, PWDs can cause peri-wound maceration due to excessive exudate accumulation. To address this issue, several modified approaches have been developed, including the use of perforated polyethylene bags containing absorbent pads and low-adherent absorbent dressings.¹¹ These alternatives allow exudate drainage and absorb small amounts of fluid. Supplementary Figure S1 shows the materials used in SOD treatment.^7,8,11 SODs can manage pressure injuries at all stages using a consistent, simple, and inexpensive procedure. Many experts view SOD treatment as a rational approach^7–11 based on moist healing concepts^12–14 and wound bed preparation.^15–17 Two randomized trials showed that the SOD treatment provides an advantage over OD treatment for stage III/IV pressure injuries,^7,18 and two Japanese guidelines on pressure injury treatment address its effectiveness.^19,20

CLINICAL PROBLEM ADDRESSED

Although two randomized trials are available for stage II pressure injuries, neither showed significant differences in healing time between SOD and standard treatments.^8,21 One study reported a mean healing time of 3.4 weeks (standard deviation [SD], 3.2) with PWD treatment and 3.5 weeks (SD, 3.3) with OD treatment, with a 95% confidence interval (95% CI) of the difference of –0.8 to 0.9 weeks. As this study was designed with statistical power to detect a difference of more than 1 week as significant,²¹ the results indicated that the difference in healing time between the two treatments was less than 1 week.

Another study found similar Kaplan–Meier curves for healing times in both groups. The estimated healing time with SOD treatment was 18.8 days (95% CI, 10.3–27.2) compared with 16.0 days (95% CI, 8.1–23.9) for conventional treatment.⁸ In addition, a comparison of symmetrical wounds in the same patient showed comparable surface area reduction rates for SOD and OD treatments in stage II injuries.²²

These findings suggest that SOD treatment is as effective as, or not inferior to, OD treatment for stage II pressure injuries. If their effectiveness is equivalent, SOD treatment offers a cost advantage. Furthermore, the SOD can treat pressure injuries at all stages by a consistent and simple procedure, from development to healing. This study aims to verify the noninferiority in effectiveness and superiority in cost of SOD compared with OD treatment for stage II pressure injuries.　

MATERIALS AND METHODS

Trial design and participants

This 12-week, prospective, randomized, controlled, noninferiority trial involved 10 wards of a Japanese psychiatric/geriatric hospital and three care facilities between August 2016 and March 2019. An open-label design was adopted because masking the intervention was impractical. This trial was registered on the UMIN Clinical Trials Registry [UMIN000023417] and was conducted in accordance with the Declaration of Helsinki and its amendments. The study design and reporting followed the CONSORT 2010 extension statement for noninferiority trials.²³ The Minakuchi Hospital Clinical Review Board approved the study protocol. The detailed information has been disclosed on the clinical research registry site (https://center6.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000026979). Written informed consent was obtained from participants if they had the ability to consent or from their guardians if they did not.

Patients aged 20 years or older with stage II pressure injuries, as defined by the NPIAP Pressure Injury Staging System,^5,6 were considered for inclusion in this study. Eligible participants had pressure injuries of 4–36 cm² (Bates-Jensen Wound Assessment Tool^24,25 score of 2–3 for size). When patients had multiple wounds, the largest wound was selected. The exclusion criteria were as follows: skin ulcers attributable to other causes (e.g., peripheral arterial occlusive disease or primary/metastatic skin cancer), poorly controlled diabetes (HbA1c >10.0% at the time of registration), and treatment with cytotoxic agents or immunosuppressants.

Baseline parameters included age, sex, mental disorders, systemic diseases (including infectious diseases, diabetes, and malignancy), hemoglobin level, body mass index, serum albumin level, Braden Scale^26,27 score, and location and surface area of the wound. Mental status was determined according to the International Statistical Classification of Diseases and Related Health Problems (10th ed.).²⁸ Systemic diseases were identified through interviews, general physical examinations, blood tests, imaging studies, and medical record searches upon enrollment. After obtaining these baseline characteristics, simple randomization was performed to allocate the consenting participants to SOD or OD treatment in a 1:1 ratio. For randomization, a researcher affiliated with the registrar’s office, who was not involved in treatment or evaluation, assigned treatments using a random number table created in Excel 2010 for Windows (Microsoft Japan Co., Ltd., Tokyo, Japan) and recorded the results on the registration form. No electronic laboratory notebook platform was used. 　

Intervention

Two research physicians and one nurse from the hospital’s wound care team treated and evaluated all wounds and educated nurses at the research facilities on local treatment and prevention protocols to standardize nursing techniques. This study used unsterilized PWD or low-adherent absorbent dressings for SOD treatment. The use of unsterilized materials does not increase adverse events, including wound infection.^7,8,10,18,21 Low-adherent absorbent dressings consist of multiple layers, including an inner layer of low-adherent perforated film to prevent sticking to the skin, an absorbent layer made of cotton, resin, or polyester fiber pads, and a hydrophobic backing layer. For OD treatment, hydrocolloid or polyurethane foam dressings were used.^1–4 The origins of the dressing materials in both groups are shown in Supplementary Table S1.

Depending on the amount of exudate and the degree of wound moistening, the appropriate dressing type was selected for each treatment group. If the wound had little exudate and tended to dry, PWDs were used in SOD treatment, whereas hydrocolloid dressings were used in OD treatment. Moist wounds with more exudate were treated with low-adherent absorbent dressings for SOD treatment and with polyurethane foam dressings for OD treatment.^1,11,18 The flowchart outlining the protocol is shown in Supplementary Figure S2. After cleansing the area with saline solution, the wound was covered with the appropriate dressing. No disinfectants, such as iodine or topical antibiotics, were used.^7,10 Supplementary Figure S3 shows the SOD application process.

After initiating SOD treatment, a foul odor or yellow exudate may be observed; however, this does not indicate wound infection or deterioration in most cases. Wound infection should be diagnosed comprehensively, including other findings such as heat, redness, and swelling of the skin surrounding the wound. Changing the dressings and cleansing the wound daily resulted in translucent and odorless exudate within 1–2 weeks without antibiotic use.^7,21 In OD treatment, dressings were changed twice a week. In both groups, dressings were changed more frequently if wounds produced abundant exudate, patients peeled off dressings, or dressings were removed by turning over. For adverse events, we first attempted to manage them by changing the type of dressings within the assigned treatment group. If severe adverse events, including wound deterioration or infection, occurred, treatment with the dressings or medications deviating from the protocol was performed as needed.

Based on the risk level evaluated using the Braden Scale, a trial-independent pressure injury prevention and management committee implemented prevention protocols,^4,29,30 including optimizing general nutritional status,³¹ maintaining skin hygiene,³² and providing appropriate mattresses and other equipment to enhance pressure redistribution.^33–38 For complications, including anemia, diabetes, and infectious diseases, each patient’s doctor provided treatment.

Observation and assessment of the wounds

At the time of registration, the wound area measurement was performed as follows: after cleansing the wound, a ruler was placed vertically on the wound and photographed using a digital camera. Using these images and Leaf Area Counter Plus software (Vector Inc., Tokyo, Japan), the surface area was calculated. The wound was assessed twice a week on days 4, 7, 11, 14, 18, 21, and so on, until the wound healed or on day 84. Wound healing was determined by consensus of the two independent investigators’ judgments by visual examination and palpation.

Outcome measures

Primary end point

A comparison of the time, in days, was required for wound healing with both treatments. A noninferiority margin was set at 7.0 days. Based on the results of previous studies,^8,21 we estimated that the difference in healing times between SOD and OD treatments was within 7.0 days, and this difference was deemed irrelevant in clinical settings based on discussions among investigators and external experts.

Secondary end points

Effectiveness

Kaplan–Meier curves of both groups were compared, with the time to wound healing as the end point.

Treatment cost

Material cost in both groups was calculated by the number of each used item and the unit price at which the hospital purchased the item. Nurses recorded the number of dressings, gauze, gloves, and the amount of saline used for each procedure.

Burden on medical practitioners

Frequency of dressing changes in both groups was compared.

Safety

Incidence of adverse events, including wound infection; indicated by redness, swelling, fever, and pus in and around the wound, maceration of peri-wound skin; excess moisture causing the stratum corneum to become swollen and whitish, and hyper-granulation; and the granulation tissue, is raised above the normal skin surface.

Frequency of wound deterioration; the wound worsens to stage III/IV and/or increases in size of the surface area.

Statistical analysis

Sample size calculation

We assumed a mean time of 21.0 days (SD, 21.0) for wound healing in both groups, based on the prior trial.²¹ Under these conditions, noninferiority would be demonstrated within the margin of 7.0 days at a one-sided significance level of 0.025 and a study power of 0.80, with a sample size of 143 per arm. Allowing a 10% loss to follow-up and unbalanced allocation, 330 participants (165 per arm) were required. Easy R (EZR; Saitama Medical Center, Jichi Medical University, Saitama, Japan)³⁹ was used for sample size planning.

Analysis of the primary end point

The primary end point was evaluated using unpaired Student’s t-test in two analysis sets: intention-to-treat (ITT) and per-protocol (PP) populations. Primary analysis was conducted on the PP population. Major protocol deviations leading to exclusion from the PP population included: -

Changing the assigned treatment group.

Missing primary end point as complete wound healing.

Significant protocol noncompliance (e.g., treatments not included in the protocol).

Whether a patient met protocol deviation criteria was determined through discussion among the three investigators.

Analysis of baseline characteristics and secondary end points

Superiority analyses were performed on an ITT basis, two-sided, with an alpha level of 0.05. Quantitative variables were analyzed using the Mann–Whitney U test and continuous variables using unpaired Student’s t-tests. For intergroup comparisons, Fisher’s exact test or χ² test was used. The time-to-event outcome was calculated using the Kaplan–Meier method, with the difference between groups estimated by a log-rank test. All analyses were performed using StatView (version 5.0; SAS Institute Inc., Cary, NC, USA) and EZR.

RESULTS

A total of 122 patients with skin ulcers were screened. Of these patients, 115 were enrolled and randomized to the SOD group (n = 56) or the OD group (n = 59). Although the estimated number of necessary participants was not achieved, patient recruitment was terminated owing to changes in the practice structure of the research facility, including research staff transfer. Figure 1 summarizes the flow of participants through the trial. Five patients in the SOD group and seven in the OD group were excluded from the PP analysis (n = 103) on account of missing the primary end point of wound healing. However, these patients were included in the ITT population (n = 115).

Figure 1.

Flow of participants during the trial. ITT, intention-to-treat; OD, occlusive dressing; PP, per-protocol; SOD, semiocclusive dressing.

The baseline demographics and wound characteristics of the participants are presented in Table 1. The two groups were well-balanced. Initially, 17 and 39 patients in the SOD group were treated with PWDs and low-adherent absorbent dressings, respectively. In the OD group, 39 and 20 patients were treated using hydrocolloid and polyurethane foam dressings, respectively. During the trial, no patient was switched from their assigned treatment group to another.

Table 1.

Baseline patient demographics and wound characteristics

Characteristics	SOD Group(n = 56)	OD Group(n = 59)	p value
Sex, female	32 (57%)	31 (53%)	0.71^a
Age, mean ± SD [year]	78.1 ± 11.5	81.1 ± 8.8	0.13^b
Hemoglobin, mean ± SD [g/dL]	11.3 ± 1.8	10.8 ± 1.5	0.99^b
Albumin, mean ± SD [g/dL]	3.1 ± 0.5	3.0 ± 0.6	0.44^b
Body Mass Index, mean ± SD	20.3 ± 2.8	20.1 ± 2.5	0.71^b
Braden Scale score, mean ± SD	15.5 ± 3.7	16.5 ± 2.6	0.09^b
Braden Scale score, median (IQR)	16 (12–19)	17 (15–18)	0.16^c
Type of mental disorder:			0.49^d
Alzheimer’s disease	11 (20%)	14 (24%)
Vascular dementia	11 (23%)	16 (27%)
Dementia with Lewy bodies/Parkinson disease with dementia	6 (11%)	2 (3%)
Mixed dementia	3 (5%)	6 (10%)
Other dementias	2 (4%)	1 (2%)
Schizophrenia	11 (20%)	13 (22%)
Mental retardation	5 (9%)	4 (7%)
Depressive disorder	3 (5%)	0 (0%)
Others	2 (4%)	3 (5%)
Systemic disease:
Systemic infectious disease	16 (29%)	17 (29%)	0.99^a
Diabetes mellitus^e	12 (21%)	11 (19%)	0.82^a
Malignancy	2 (4%)	5 (8%)	0.44^a
Arrhythmia and heart failure	3 (5%)	3 (5%)	0.99^a
Others^f	3 (5%)	4 (7%)	0.99^a
Surface area of pressure injuries, mean ± SD [cm²]	9.1 ± 6.1	8.5 ± 6.7	0.67^b
Location of pressure injuries:			0.18^d
Sacrum	13 (23%)	19 (32%)
Heel/feet	13 (23%)	9 (15%)
Hip	6 (11%)	4 (7%)
Greater trochanter	7 (13%)	4 (7%)
Back	1 (2%)	4 (7%)
Leg	12 (21%)	7 (12%)
Arm	4 (7%)	8 (14%)
Ischium	0 (0%)	2 (3%)
Coccyx	0 (0%)	2 (3%)

^aFisher’s exact test; ^bUnpaired Student’s t-test; ^cMann–Whitney U test; ^dχ² test. To compare categorical variables in descriptive data between two groups, a Fisher’s exact test or χ² test was performed. The unpaired Student’s t-test was applied for parametric variables, and Mann–Whitney U test for nonparametric variables. ^*p < 0.05 was accepted as significant. ^eThe mean HbA1c levels of patients with diabetes were 7.1% (SD, 1.5) and 6.8% (SD, 0.7) in the SOD and OD groups, respectively. ^fSystemic disease other than those listed included one patient with pulmonary embolism, one with intestinal obstruction, and one with severe bronchial asthma in the SOD group, and one with femoral neck fracture, one with severe chronic kidney disease, one with chronic subdural hemorrhage, and one with intestinal tuberculosis in the OD group. IQR, interquartile range; OD, occlusive dressing; SD, standard deviation; SOD, semiocclusive dressing.

Outcome measures

Primary end point

In the PP analysis, the mean healing time in the SOD group was 19.7 days (SD, 16.4; 95% CI, 15.1–24.3), whereas that in the OD group was 22.5 days (SD, 18.4; 95% CI, 17.4–27.6). No significant difference was observed (p = 0.4175). The 95% CI of the difference was –4.0 to 9.6. Since its lower limit was within the noninferiority margin (Fig. 2), the noninferiority of SOD to OD treatment was confirmed. The study power was 0.81.

Figure 2.

Comparison of the time in days required to complete wound healing with both treatments: verification of noninferiority. The 95% CI of the difference was –4.0 to 9.6 in the PP analysis and –5.0 to 13.7 in the ITT analysis. Since the lower bounds in both analyses did not exceed the noninferiority margin of 7.0 days, the noninferiority of SOD to OD treatment was verified. CI, confidence interval.

The ITT analysis also indicated the noninferiority of SOD to OD treatment. The mean healing time in the SOD group was 25.4 days (SD, 24.2; 95% CI 18.9–31.9) compared with 29.8 days (SD, 26.4; 95% CI 22.9–36.7) in the OD group. The difference was not statistically significant (p = 0.3602). The 95% CI of the difference was –5.0 to 13.7, and the lower bound was within the noninferiority margin (Fig. 2). The study power was 0.66.

Secondary end points

Effectiveness

The Kaplan–Meier curves for both groups were comparable (Fig. 3), and no significant difference was detected (p = 0.249). The estimated median healing times in the SOD and OD groups were 14 days (95% CI 14–18) and 18 days (95% CI 14–25), respectively.

Figure 3.

Comparison of the Kaplan–Meier plots between the two groups, with the period until wound healing as the end point. The curves for both groups were similar (p = 0.249). The healing rate in the SOD group at 21, 42, and 84 days was 70% (39/56), 80% (45/56), and 91% (51/56), respectively, whereas those in the OD group were 61% (36/59), 78% (46/59), and 88% (52/59), respectively.

Cost and burden of medical practitioners

OD treatment had a significantly higher mean cost than SOD treatment, whereas the frequency of dressing changes in the SOD group was significantly higher than that in the OD group (Table 2, Supplementary Fig. S4a, S4b).

Table 2.

Comparison of material costs and frequency of dressing changes

	SOD Group(n = 56)	OD Group(n = 59)	p value
Total Material Cost	69,331	653,903	<0.01^*
Mean ± SD	1,238 ± 1,228	11,083 ± 16,828
Median (IQR)	771 (510–1,610)	4,591 (2,696–12,454)
Cost of dressing materials	15,064	625,136
Plastic wrap	487	0
Low-adherent absorbent dressing	14,577	0
Hydrocolloid dressing	0	297,818
Polyurethane foam dressing	0	327,318
Cost of supplies used in the procedure	54,267	28,767
Gauze	22,880	12,201
Glove	19,248	10,272
Saline solution	12,139	6,294
Numbers of dressing changes	1,470	754	<0.01^*
Mean ± SD	26 ± 23	13 ± 12

The unit of cost was the Japanese yen. p values were based on Mann–Whitney U test for comparison of material costs and unpaired Student’s t-test for frequency of dressing changes.

p < 0.05 was considered significant. The analyses were performed on the ITT basis.

ITT, intention-to-treat.

Safety

The incidence of adverse events and frequency of wound deterioration were comparable between the groups (Table 3, and Supplementary Fig. S4c).

Table 3.

Incidence of adverse events and frequency of wound deterioration

	SOD Group (n = 56)	OD Group (n = 59)	p value
Wound infection	1 (2%)	2 (3%)	0.99
Hypergranulation	0 (0%)	3 (5%)	0.24
Maceration	6 (11%)	5 (8%)	0.76
Wound deterioration	1 (2%)	3 (5%)	0.62

Fisher’s exact test was performed. *p < 0.05 was considered significant.

OD, occlusive dressing; SOD, semiocclusive dressing.

DISCUSSION

Comparing the mean healing times for both treatments verified the noninferiority of SOD to OD treatment in effectiveness for stage II pressure injuries, whereas this trial had a significant qualitative issue because the sample size was smaller than planned. Since the insufficient sample size has reduced the study power and increased the risk of accepting a false noninferiority claim, the reliability of this study must be considered to be low. However, the statistical power of this study met the 0.80 threshold set during the study design, because the mean healing time in the SOD group and the SDs in both groups were smaller than initially estimated. Therefore, the results may carry a certain degree of credibility although the level of confidence remains limited. The contributing factors to the quality of this trial were the low number of dropouts, lack of treatment crossover, and low recruitment of patients who did not respond to the treatment, which would reduce the risk of falsely accepting noninferiority. The results showing noninferiority in both the PP and ITT analyses also enhanced the reliability of this study. Nevertheless, to confirm the noninferiority of SOD to OD treatment, larger, multicenter trials are required.

Regarding secondary outcomes, the Kaplan–Meier curves of both groups were similar. In addition, SOD treatment demonstrated a significant economic advantage over OD treatment. These results confirm our hypothesis that SOD treatment is more cost-effective than OD treatment for stage II pressure injuries. Because the SOD can manage more exudate than the OD, SOD treatment is more effective for stage III/IV pressure injuries with abundant exudate.^7,10,18,22 Conversely, stage II pressure injuries produced only sufficient exudate to be adequately managed by the OD; therefore, the effectiveness of both treatments was clinically equivalent.²¹

Thus, the SOD can treat all stages of pressure injuries with a consistent and simple procedure, from development to healing. SOD treatment has relieved expert physicians and nurses from the necessity of deciding which dressing material or ointment should be used depending on the wound condition. Therefore, less effort needs to be expended on local treatment, allowing resources to be allocated for risk management, including enhancing pressure redistribution, maintaining skin cleanliness, and optimizing nutritional status. Although the SOD group required more frequent dressing changes than the OD group, the caregiver burden for SOD treatment was not high. Because the treatment procedure was simple, dressing changes could be performed quickly, often in conjunction with other care, such as diaper changes and bathing. OD treatment may be more suitable for outpatients, as frequent dressing changes can increase the burden on patients, in terms of medical expenses, travel costs, and time. An algorithm for selecting the SOD and OD based on the findings from current and previous studies is shown in Supplementary Figure S5.^{7,8,10,18,21,22}

From a safety perspective, no obvious differences were observed between the two treatments. As long as proper debridement, appropriate method and frequency of procedures, and careful monitoring for signs of infection are performed, SOD treatment is a safe and cost-effective option,^7,8,18,21 even in settings where access to medications and medical supplies is restricted, involving nursing homes and home care.¹¹ However, improper treatment may worsen the wound, such as by sealing the wound with plastic wrap, not changing the dressing for several days, or not appropriately managing wound infection.⁴⁰

In addition to the small sample size, this study has some limitations. First, labor costs were not considered when calculating treatment costs. The time required to change dressings and details on the caregiver burden was not taken into account. Because dressing changes were required more frequently, the labor costs associated with SOD treatment may be higher than those associated with OD treatment. However, because the time and effort required to change SODs are minimal, the difference in labor costs between the groups may be insignificant. Thus, SOD treatment may still have an economic advantage over OD treatment. Second, the small sample size may have reduced statistical power and underestimated the significance of the differences in some end points. This may have also introduced bias, affecting the equality of the underlying background characteristics between the groups.

Third, we may not have adequately searched for and treated systemic diseases or local blood flow disturbances that impede wound healing. Because this study was conducted in the psychiatric hospital and care facilities, the examinations and treatments we could perform for physical illness were partially limited, and some patients refused to undergo aggressive and invasive examinations and treatments. Finally, the safety verification was insufficient. More detailed information regarding safety should be collected through observation over a longer period with a larger sample size.

In addition, we present research questions that have not yet been clarified and that should be addressed in future research. -

Subgroup analysis of patient and wound conditions, including location of pressure injuries, acute or chronic wounds, patients treated in intensive/critical care unit, patients with terminal illness, patients in long-term care, and outpatients.

Subjective evaluation by the patient, including pain, comfort, and adherence.

Advancing SOD treatment, such as combining SOD treatment with some topical medications to promote healing and prevent complications.

INNOVATION

This randomized, controlled trial demonstrated the noninferiority in effectiveness and the superiority in cost of the SOD compared with the OD for treating stage II pressure injuries. Previous trials have shown that SOD treatment is more effective than OD treatment for stage III/IV pressure injuries. Therefore, the SOD can treat pressure injuries at all stages effectively, economically, and safely using a consistent and simple procedure from wound development to healing.

KEY FINDINGS

SODs are not inferior to ODs to treat stage II pressure injuries.

SOD treatment is significantly more cost-effective than OD treatment.

No significant difference in adverse events was observed between SOD and OD treatments.

Clinical implications: The SOD is a viable and low-cost alternative for stage II pressure injuries.

AUTHORS’ CONTRIBUTIONS

J.T., K.N., R.N., and H.H. collected the data; R.N. carried out the randomization; J.T., K.N., and R.N. analyzed the data; J.T. drafted the article; O.Y. and M.M. provided edits to the article; and J.T., O.Y., and M.M. designed the study.

Footnotes

ACKNOWLEDGMENTS AND FUNDING SOURCES

This work was supported by research grants from Minakuchi Hospital and Minamikusatsu Keyaki Clinic. The authors would like to thank Honyaku Center Inc. for English language editing.

AUTHOR DISCLOSURE AND GHOSTWRITING

The authors declare no financial interests or conflicts of interest. No ghostwriters were employed.

ABOUT THE AUTHORS

Jun Takahashi, MD, is the chief medical director of Minakuchi Hospital, with research interests in the treatment of pressure injuries. Kayoko Nakae, RN, is a ward chief nurse at Minakuchi Hospital. Osamu Yokota, MD, PhD, is the director of Kinoko Espoir Hospital and a researcher at Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Department of Neuropsychiatry. Rena Nakata is a chief medical clerk at Minakuchi Hospital. Hayato Hasegawa, MD, is a staff doctor at Minakuchi Hospital. Masaharu Miyagawa, MD, is the director of Minamikusatsu Keyaki Clinic and a specialist in geriatric medicine.

Supplemental Material

Abbreviations and Acronyms

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