Allman 1987.

Study characteristics
Methods	Study objective: to compare the effectiveness and adverse effects of air‐fluidised beds and conventional therapy for patients with pressure sores Study design including the number of centres: randomised controlled trial, single centre Study grouping: parallel group Duration of follow‐up: median 13 days Number of arms: 2 Study start date and end date: recruited between October 1984 and March 1986 Care setting: urban, academic referral, and primary care medical centre
Participants	Baseline characteristics Inclusion criteria: age greater than 18 years old; presence of a pressure sore on the sacrum, buttocks, trochanters or back; activity expected to be limited to bed or chair in the hospital for at least 1 week; patient expected to live at least 1 week; informed consent obtained Exclusion criteria: had been in the trial previously or a skin graft or flap planned for the pressure sore within 1 week Sex (M/F): 27/38 overall. 11/20 in air‐fluidised bed; 16/18 in conventional therapy Age (years): mean 65.5 (SD 15.6) in air‐fluidised bed, 67.6 (18.3) in conventional therapy The stage of pressure ulcers at baseline: 16 superficial and 15 deep ulcers on air‐fluidised bed; 20 superficial and 14 deep ulcers on conventional therapy. Median total surface area 7.8 cm2 (range 0.3 to 83.2) on air‐fluidised bed, 10.8 (0.4 to 180.3) on conventional therapy Group difference: no difference Total number of participants: 72 patients (65 completed the study) Unit of analysis: individuals Unit of randomisation (per patient): individuals
Interventions	Intervention characteristics Air‐fluidised bed Description of interventions: air‐fluidised bed (Clinitron Therapy, Support Systems International, Inc.)… contain ceramic beads … warm, pressurised air is forced up through the beads, on the characteristics of a fluid NPIAP S3I classification: non‐powered, reactive air‐fluidised surface Number of participants randomised: not given Number of participants analysed: 31 Co‐interventions: repositioning every 4 hours without use of other anti‐pressure devices Conventional therapy Description of interventions: used a vinyl alternating air‐mattress covered by a 19 mm thick foam pad (Lapidus Air Float System, American Pharmaceal Company) on a regular bed NPIAP S3I classification: non‐powered, reactive foam surface plus powered, alternating pressure (active) air surface Number of participants randomised: not given Number of participants analysed: 34 Co‐interventions: repositioning every 2 hours and elbow or heel pads as needed
Outcomes	Proportion of participants developing a new pressure ulcer Outcome type: binary Time points: median 13 days Reporting: partially reported Measurement method (e.g. scale, self‐reporting): skin breakdown or epidermal necrosis manifested by eschar over a bony prominence; defined by Shea system; not staged Definition (including ulcer stage): new skin breakdown Dropouts: 7 withdrew prior to follow‐up and excluded from analysis (6 died, 1 withdrew due to nausea and dislike of the air‐fluidised bed) Notes (e.g. other results reported): 9 of 31 on air‐fluidised beds vs 15 of 34 on conventional therapy (P = 0.24) Time to pressure ulcer incidence Reporting: not reported Support‐surface‐associated patient comfort Outcome type: categorical Time points: median 13 days Reporting: partially reported Definition and measurement method (e.g. scale, self‐reporting): patients with change in comfort from baseline. Level of comfort assessed by asking the patient to respond to a second question scored from 1 to 4: “Which of the following best describes the bed you are using here in the hospital: very comfortable, comfortable, uncomfortable, or very uncomfortable?” Dropouts and reasons: 7 withdrew prior to follow‐up and excluded from analysis (6 died, 1 withdrew due to nausea and dislike of the air‐fluidised bed) Data and results: 8 comfort increased, 4 no change and 1 decreased on air‐fluidised bed; 3 increased, 4 no change and 6 decreased on conventional therapy (P = 0.04) Notes (e.g. other results reported): All reported adverse events Outcome type: binary Time points: median 13 days Reporting: partially reported Definition and measurement method (e.g. scale, self‐reporting): patients developing complications Dropouts and reasons: 7 withdrew prior to follow‐up and excluded from analysis (6 died, 1 withdrew due to nausea and dislike of the air‐fluidised bed) Data and results: 8 died, 2 pneumonia, 10 urinary tract infections, 6 hypotension, 5 hypernatraemia, 5 oliguria, 7 sepsis, 16 fever, and 3 heart failure on air‐fluidised bed; 7 died, 4 pneumonia, 7 urinary tract infections, 7 hypotension, 5 hypernatraemia, 8 oliguria, 6 sepsis, 22 fever, and 6 heart failure on conventional therapy Notes (e.g. other results reported): some patients appeared to have multiple adverse events Health‐related quality of life (HRQOL) Not reported Cost‐effectiveness Not reported Outcomes that are not considered in this review but reported in trials: Ulcer healing Change in total surface area Patients improved 50% reduction in total surface area Pain response
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “Patients were randomly allocated to treatment groups in two strata in balanced blocks of six with stratification … The randomization sequence was determined using a table of random numbers …” Comment: low risk of bias due to the use of a proper randomisation method.
Allocation concealment (selection bias)	Unclear risk	Quote: “… treatment allocations were placed in envelopes sealed and numbered sequentially. After establishing eligibility, one of the investigators selected the unopened envelope with the lowest number in the appropriate strata and allocated the patient to the treatment indicated on the enclosed card” Comment: unclear risk of bias because it is unclear if the envelopes are opaque.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Comment: no information provided.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome group: ulcer incidence Comment: no information provided.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Outcome group: all outcomes Comment: low risk of bias because of the low rate of attrition (7/72, 9.7%).
Selective reporting (reporting bias)	Low risk	Comment: the study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre‐specified.
Other bias	Low risk	Comment: the study appears to be free of other sources of bias.