Tang 2019.

Study characteristics
Methods	2‐arm RCT Conducted in‐home and hospital settings in China The duration of follow‐up was a maximum of 3 months
Participants	60 participants: all included in the analysis Inclusion criteria listed: Pressure ulcer graded III or IV according to the European Pressure Ulcer Advisory Panel Grading System; the blood glucose level and nutritional index level were well controlled, and the body mass index (BMI) was at the same level; the patient's age was > 60 years old Exclusion criteria listed: Patients with malignant tumours; the wound has large blood vessel exposure and nerve exposure; the wound has active bleeding, necrotic tissue, and contraindications to debridement, no debridement or secondary osteomyelitis without treatment, or there is an undetected sinus; there are systemic complications affecting wound repair, such as autoimmune diseases, multiple organ failure and so on
Interventions	Group A: the wound was initially evaluated for the whole body and wound; implement conservative instrument debridement combined with autolytic debridement; selected the appropriate new dressing according to the evaluation results of the wound, adopted the wet dressing change method, and determined the frequency of dressing change and dressing change according to the wound exudation until the rotten meat in the wound bed disappeared Group B: wound evaluation, cleaning, and debridement were the same as those in the control group; the dressing was cut according to the size of the wound, and the sealing film was trimmed to completely cover the dressing and exceed the area of 3~5cm beyond the edge of the wound. The operator pinched the sealing film with his index finger and thumb, cut a small hole with a diameter of 1~2cm on the film, and then pasted a suction cup; connected the NPWT treatment host, and set the pressure through the touch screen of the NPWT treatment instrument. The pressure setting range of pressure ulcers was ‐80 to ‐120 mm Hg; guided the patient's family members on the operation, observation, and possible troubleshooting of the machine setting, and give health education; after the patient took the machine home, the stoma therapist observed and guided the effect of negative pressure treatment through WeChat video, voice, and other Internet platforms. If there was a fault, it would be eliminated in time. For problems that could not be solved remotely, the stoma therapist would provide on‐site service; the dressing shall be changed according to the drainage fluid and wound conditions, and the dressing shall be changed once in the outpatient department in 5~7 days until the patient's wound bed was free of rotten meat and the wound red granulation tissue was completely covered
Outcomes	Primary outcome: none Second outcome:  Times of dressing change Rate of change in wound size Pain
Notes	Funding source: no details of funding sources
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Pairing based on patients' age, basic physical conditions, and the stage of pressure ulcers, each pair was divided into the control group and intervention group with 30 patients in each group according to the random number table". Comment: there are no further details of the randomisation process, we can not make a judgment according to the author's description.
Allocation concealment (selection bias)	Unclear risk	Comment: no information.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote: "The ostomy therapist observed the effect and guided the use of NPWT treatment through WeChat video, voice, and other Internet platforms". Comment: no detailed information.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "No participants withdraw from the study" Comment: all participant data were included in the analysis.
Selective reporting (reporting bias)	Low risk	Comment: outcomes identified in the methods section were reported in the results (and were outcomes that would be expected to be included in such a study). Protocol not seen.
Other bias	High risk	Quote: "After the patient took the machine home, the ostomy therapist observed and guided the use of NPWT through WeChat video, voice, and other Internet programs" Comment: researchers may not be able to control the potential bias risk.