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Alginate dressings for healing diabetic foot ulcers

  1. Jo C Dumville1,*,
  2. Susan O'Meara2,
  3. Sohan Deshpande3,
  4. Katharine Speak4

Editorial Group: Cochrane Wounds Group

Published Online: 25 JUN 2013

Assessed as up-to-date: 11 APR 2013

DOI: 10.1002/14651858.CD009110.pub3


How to Cite

Dumville JC, O'Meara S, Deshpande S, Speak K. Alginate dressings for healing diabetic foot ulcers. Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD009110. DOI: 10.1002/14651858.CD009110.pub3.

Author Information

  1. 1

    University of Manchester, Department of Nursing, Midwifery and Social Work, Manchester, UK

  2. 2

    University of York, Department of Health Sciences, York, UK

  3. 3

    Kleijnen Systematic Reviews, York, UK

  4. 4

    York, UK

*Jo C Dumville, Department of Nursing, Midwifery and Social Work, University of Manchester, Manchester, M13 9PL, UK. jo.dumville@manchester.ac.uk.

Publication History

  1. Publication Status: New search for studies and content updated (no change to conclusions)
  2. Published Online: 25 JUN 2013

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Characteristics of included studies [ordered by study ID]
Ahroni 1993

MethodsSingle-centred, 2-armed RCT comparing a calcium-alginate dressing (Sorbsan, Aspen Medical, previously Dow B Hickman Inc.) with dry gauze (Owens Non-Adherent dressing) undertaken in the USA. Duration of follow-up: stated as 4 weeks, although some data collected beyond this point, but duration of this post-4 week period not specified.


Participants39 participants.
Inclusion criteria: patients with diabetic foot ulcers that penetrated epidermis but did not significantly involve joint spaces, tendons or bone.
Exclusion criteria: patients previously enrolled in the study; those with evidence of systemic toxicity (high fever, hypotension or metabolic decompensation); patients who required inpatient management of ulcers at time of initial evaluation (severe infection, ischaemia, extensive cellulitis, lymphangitis, deep necrosis, gangrene, crepitus or gas in tissue, or osteomyelitis or presumed deep infection); those unable or unwilling to comply with either daily wound care regimen or to come to weekly clinic visits.


InterventionsGroup A (n = 20): 2 layers of calcium-alginate dressing (Sorbsan, Aspen Medical) changed daily.
Group B (n = 19): single layer of dry, fine mesh gauze (Owens Non-Adherent dressing) changed twice a day.
Co-intervention: all wounds were cleansed with a half-strength hydrogen peroxide solution and rinsed with normal saline.


OutcomesPrimary outcome: ulcer healing (number of ulcers healed at 4 weeks; number of ulcers healed at post 4 week follow-up; healing rate mm2/day; relative odds of non-healing).
Secondary outcomes: amputations; adverse events.

Health-related quality of life; costs and ulcer recurrence not reported.


NotesTrial data:  Analysis 4.1

Funding source: Dow B Hickam Inc and Veterans Affair Rehabilitation: research and development.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskQuote: "Subjects were randomly assigned to four weeks of daily dressing change with..."
Comment: method of generating the random schedule not reported.

Allocation concealment (selection bias)Unclear riskComment: no mention of allocation concealment in study report.

Blinding of participants and personnel (performance bias)
All outcomes
High riskQuote: "Because of differences in the appearance of the two dressings a blinded study was not feasible" 
Comment: blinding of participants and personnel not done. 

Blinding of outcome assessment (detection bias)
All outcomes
High riskQuote: "Because of differences in the appearance of the two dressings a blinded study was not feasible"  
Comment: blinding of outcome assessors not done. 

Incomplete outcome data (attrition bias)
All outcomes
Low riskComment: no indication of incomplete outcome data/attrition in paper.

Selective reporting (reporting bias)Low riskComment: based on paper only, protocol not obtained.

Other biasUnclear riskComment: some differences in baseline characteristics between groups. Mean duration of ulcer 132.9 days in Group A and 74.9 days in Group B. Adjusted for in one analysis (logistic regression).
Study was funded by commercial organisation.

Baker 1993

MethodsSingle-centred, 2-armed RCT comparing a calcium alginate dressing (Sorbsan, Aspen Medical) with a foam dressing (Allevyn, Smith and Nephew) undertaken in the UK.
Duration of follow-up: until the wound healed, or for a maximum period of 12 weeks.


Participants20 participants.
Inclusion criteria: patients > 18 years old with clean diabetic foot ulcers, neuropathic in origin, located on weight-bearing areas of foot; able to give informed consent; willingly compliant to requirements of study protocol; geographically able to comply with the study's demands.
Exclusion criteria: patients with necrotic, sloughy ulcers or peripheral vascular disease; presence of infection in ulcerative foot; history of poor compliance; unable to attend regularly, or unable to follow simple instructions; those who could not comprehend the nature of the trial.


InterventionsGroup A (n = 10): calcium alginate dressing (Sorbsan, Aspen Medical). A secondary low adherent absorbant dressing was used.

Group B (n = 10): foam dressing (Allevyn, Smith & Nephew). No secondary dressing was applied .
In both groups, dressings were cut to the required size, but they did not overlap the wound margins by more than 3 cm or by less than 0.5 cm. The dressings were secured by standard podiatric methods; e.g. padding and or strapping. Frequency of dressing change depended on the quantity of exudate produced by the ulcers. If, upon removal, either dressing should appear to be stuck, they were to be irrigated, as necessary, with sterile saline.
Co-intervention: ulcers were cleansed with warm sterile saline only, and debridement was undertaken where required.


OutcomesPrimary outcome: ulcer healing (number of ulcers healed; median healing time).
Secondary outcomes: not reported.


NotesTrial data:  Analysis 4.1

Funding source: not reported.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskQuote: "Each subject will be randomly allocated to one of the two treatment groups either to the Allevyn or the Sorbsan group. This will be determined by the randomisation code which is computer generated." 
Comment: method of generation of random schedule reported.

Allocation concealment (selection bias)Unclear riskComment: the process of randomising participants, including who did this was not reported.

Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: no mention of blinding in study report.

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: no mention of blinding in study report.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: one withdrawal (1/20 = 5%). Viewed as limited attrition.

Selective reporting (reporting bias)Low riskComment: based on paper only, protocol not obtained.

Other biasUnclear riskComment: funding source not reported.

Donaghue 1998

Methods2-armed RCT (not clear if single- or multi-centred) comparing a collagen-alginate dressing (Fibracol, Johnson & Johnson Medical) with saline-moistened gauze undertaken in the USA. Duration of follow-up: until the target ulcer healed, or for a maximum of 8 weeks.


Participants75 participants.
Inclusion criteria: diabetic patients ≥ 21 years old with foot ulceration of at least 1 cm2 in size after initial debridement; adequate nutritional intake (indicated by a serum albumin of > 2.5 g/dl) and adequate blood flow to the lower extremities (indicated by palpable pulse and/or normal noninvasive tests).
Exclusion criteria: patients with severe renal or liver impairment (indicated by creatinine levels and liver function tests 2 or more times higher than normal); presence of any serious medical disorders that could interfere with wound healing; evidence of osteomyelitis (diagnosed by the existence of a deep ulcer probing to bone, or by radiographic findings); clinical signs of infection; history of drug or alcohol abuse.


InterventionsGroup A (n = 50): collagen-alginate dressing (Fibracol, Johnson & Johnson Medical).
Group B (n = 25): saline-moistened gauze.
In both group, patients or caregivers also were given explicit instructions for dressing changes and were told to change the wound dressing as often as required.
Co-intervention: weight-bearing limitation in all participants was achieved by employing the standard procedure of applying a self-adhesive felted foam dressing to the foot with a window at the site of the ulcer and the use of healing sandals.


OutcomesPrimary outcome: ulcer healing (number of ulcers healed; mean time to healing; % ulcers with 75% or greater reduction in wound area; mean time to 75% healing in weeks).
Secondary outcomes: adverse events.

Health-related quality of life; amputations; costs and ulcer recurrence not reported.


NotesTrial data:  Analysis 4.1

Adverse events not reported for each arm. Also important to note that whilst an ITT analysis was undertaken, including the 14 people that were withdrawn, the treatment of this missing data was not discussed. We assumed that withdrawals were treated as not having healed.
Funding Source: Johnson & Johnson Medical Arlington, TX.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskQuote: "Patients were assigned randomly in a 2:1 ratio open-label design"
Comment: method of generation of random schedule not reported.

Allocation concealment (selection bias)Unclear riskComment: the process of randomising participants, including who did this, was not reported.

Blinding of participants and personnel (performance bias)
All outcomes
High riskQuote: "Patients were assigned randomly in a 2:1 ratio open-label design"
Comment: This was labelled an open trial.

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskQuote: "Patients were assigned randomly in a 2:1 ratio open-label design"
Comment: This was labelled an open trial not clear if blinded evaluation was conducted.

Incomplete outcome data (attrition bias)
All outcomes
Low riskQuote: "sixty-one of the original 75 (81%) enrolled patients completed the study."

Quote: "All 75 patients enrolled were included in this intention to treat analysis"
Comment: it was unclear what assumptions were made about the missing data.

Selective reporting (reporting bias)Unclear riskComment: based on paper only, protocol not obtained.

Other biasUnclear riskComment: funded by commercial organisation.

Foster 1994

Methods2-armed RCT (not clear whether single- or multi-centred) comparing a calcium-alginate dressing (Kaltostat, ConvaTec) with a foam dressing (Allevyn, Smith & Nephew) undertaken in the UK.
Duration of follow-up: until ulcer healed, or for a maximum of 8 weeks.


Participants30 participants.
Inclusion criteria: patients > 18 years old with clean diabetic foot ulcers, willing and able to comply with study protocol.  
Exclusion criteria: sloughy, necrotic or infected ulcers.


InterventionsGroup A (n = 15): calcium-alginate dressing (Kaltostat, ConvaTec). The dressing was moistened with saline. A perforated film absorbent dressing was used as a secondary dressing, this was secured with hypo-allergic tape or a conforming bandage, depending on the state of the skin.

Group B (n = 15): foam dressing (Allevyn, Smith & Nephew). Where surrounding skin was in good condition, the dressing was secured with hypo-allergic tape. If the skin was atrophic or fragile, then no tape was applied, but a conforming bandage was used to secure the dressing. To apply the dressing to patients' lesser toes, a strip of polyurethane foam dressing was doubled over and fastened at the sides to form a sleeve that fitted over the toe.  

Co-interventions: none reported.  


OutcomesPrimary outcome: ulcer healing (number of ulcers healed; ulcers improved; median time to healing).
Secondary outcomes: adverse events.

Health-related quality of life, amputations, costs and ulcer recurrence not reported.         


NotesTrial data:  Analysis 4.1

Dressing performance parameters such as patient comfort and ease of removal were assessed using 3-point graded categorical scores. For each parameter the mean category score for each patient over the repeated dressing assessment was calculated. These data were not extracted, as this approach has not been validated and does not facilitate comparison between studies.
Funding source: not reported.


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskQuote: "Thirty out patients entered the study and 15 were randomised to each dressing"
Comment: method of generation of random schedule not reported.

Allocation concealment (selection bias)Unclear riskComment: the process of randomising participants, including who did this was not reported.

Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: no mention of blinding in study report.

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: no mention of blinding in study report.

Incomplete outcome data (attrition bias)
All outcomes
Unclear riskComment: 4 participants were withdrawn from the alginate group (4/30 = 13%). There were no withdrawals from the foam group. It is not clear how data from the withdrawn participants were used.

Selective reporting (reporting bias)Low riskComment: based on paper only, protocol not obtained.

Other biasUnclear riskComment: some differences in baseline characteristics between groups, e.g. mean age 61 years in Group A and 70 years in group Group B. Small sample size meant trial was at high risk of chance imbalance.
Funding source: not reported

Jude 2007

MethodsMulti-centred, 2-armed RCT comparing a calcium-alginate dressing (Algosteril, Smith & Nephew) with a fibrous-hydrocolloid (hydrofibre) dressing with 1.2% ionic silver (Aquacel Ag, ConvaTec) undertaken in the UK, France, Germany, and Sweden. Duration of follow-up: 8 weeks.


Participants134 participants.
Inclusion criteria: patients with Type 1 or Type 2 diabetes mellitus (HbA1c ≤ 12%); serum creatinine ≤ 200 mol/l; neuropathic or neuro-Ischaemic diabetic foot ulcers classed as Wagner grade 1 or 2; all wounds > 1 cm2 in area.     
Exclusion criteria: patients with known allergies to dressings being investigated; known or suspected malignancy near ulcer; taking systemic antibiotics > 7 days prior to enrolment; inadequate arterial perfusion defined by ankle-to-brachial index < 0.8, or great toe systolic blood pressure < 40 mmHg or forefoot TcPO2 < 30 mmHg (subject supine) or < 40 mmHg (participant sitting).   


InterventionsGroup A (n = 67): calcium-alginate dressing (Algosteril, Smith & Nephew). Manufacturers' instructions were followed, and dressing was moistened before use on dry wounds, and changed on leakage or at evaluation or every 7 days as indicated (except for infected wounds on which the dressing was changed daily).                       

Group B (n = 67): fibrous-hydrocolloid (hydrofibre) dressing with 1.2% ionic silver (AQUACEL® Ag, ConvaTec). Left in place and changed on leakage or at evaluation or every 7 days as indicated.  

In both groups, ulcers were cleansed using sterile saline, each dressing was covered with a sterile, non-adherent foam dressing.

Co-intervention: accommodative footwear for non-plantar ulcers and off-loading for planter ulcers delivered as required.  


OutcomesPriamry outcome: ulcer healing (number of ulcers healed; velocity of healing; mean time in days to healing; reduction in ulcer area; reduction in ulcer depth).
Secondary outcomes: adverse events, costs (mean number of dressing changes during study).

Health-related quality of life, amputations, and ulcer recurrence not reported.


NotesTrial data:  Analysis 4.1

22 participants had clinically infected ulcers at baseline, 13 in Group A and 9 in Group B. On enrolment antibiotics were prescribed to 8 in Group A and 13 in Group B.
Funding source: ConvaTec (Bristol Myers Squibb).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Low riskQuote: " Individuals were randomly assigned to receive either...(dressing details)... according to instructions in a sealed envelope and stratified according to whether or not systemic antibiotics were being administered for treatment of the study ulcer"
Comment: method of generation of random schedule reported.

Allocation concealment (selection bias)Unclear riskComment: not clear if envelopes were sequentially numbered, opaque and sealed.

Blinding of participants and personnel (performance bias)
All outcomes
Unclear riskComment: no mention of blinding in study report.

 

Blinding of outcome assessment (detection bias)
All outcomes
Unclear riskComment: no mention of blinding in study report.

Incomplete outcome data (attrition bias)
All outcomes
Low riskComment: 21 participants recorded as discontinuing treatment, however, it does not seem that these were study withdrawals. All randomised participants included in the analysis.

Selective reporting (reporting bias)Low riskComment: based on study report, protocol not obtained.

Other biasUnclear riskComment: funded by commercial organisation.

Lalau 2002

MethodsA multi-centred, 2-armed  RCT comparing a calcium alginate dressing (Algosteril, Smith & Nephew) with Vaseline gauze (Vaselitulle, Solvay Pharma), undertaken in France.
Duration of follow-up:  6 weeks. The study report stated, however, that, due to premature cessation of treatment in 13 out of 77 patients, it was decided to shorten the period of the efficacy analysis to 4 weeks. The authors said that "this reduction was not accompanied by a revision of the criterion of efficacy and all patients remained included in the 6-week tolerance analysis study" (it was not clear to what the mention of "tolerance analysis" refers).     


Participants77 participants.
Inclusion criteria: patients < 75 years old, with Type 1 or 2 diabetes and a foot lesion in phase of cleansing (granulation tissue surface of less than 50% of wound area) with surface area between 1 cm2 and 50 cm2.  
Exclusion criteria: HBA1c level of more than 10%; presence of clinical infection with redness, swelling, warmth and peri-wound erythema; osteomyelitis on plain radiography or probing of bone; a tunnelled wound; any severe hypovascularisation. 


InterventionsGroup A (n = 39): calcium-alginate dressing (Algosteril, Smith & Nephew).
Group B (n = 38): Vaseline gauze (Vaselitulle, Solvay Pharma).
In both groups dressings were applied directly to the wound for up to 6 weeks. Dressing were changed every day until debridement, and then every 2 to 3 days.  No other treatment was permitted except the use of saline solution. In both groups sterile gauze was applied as secondary dressing.
Co-interventions: conservative management was carried out using appropriate pressure-relieving methods.


OutcomesPrimary outcome: ulcer healing (% of ulcers with granulated tissue over 75% of wound area and 40% decrease in wound surface area; mean change in wound area).
Secondary outcomes: adverse events (pain on dressing change and other events); costs (total number of dressing changes). Health-related quality of life, amputations and ulcer recurrence not reported.                          


NotesTrial data:  Analysis 4.1

Funding source: laboratories Brothier (Parris-Nanterre, France).


Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskQuote: "Patients were randomly assigned to receive treatment with either calcium alginate or Vaseline gauze".
Comment: method of generation of random schedule not reported.

Allocation concealment (selection bias)Unclear riskComment: the process of randomising participants, including who did this was not reported.

Blinding of participants and personnel (performance bias)
All outcomes
High riskQuote: "This was an opened controlled trial for 6 weeks with blinded evaluation."
Comment: the trial was stated as being open-label. No other details provided in the text.

Blinding of outcome assessment (detection bias)
All outcomes
Low riskQuote: "An independent investigator, blind to allocated treatment, was assigned to analyse wound area surfaces."
Comment: outcome assessors were blinded.

Incomplete outcome data (attrition bias)
All outcomes
High riskComment: In total 13 patients did not complete the full 6 weeks of the study. It was unclear how these were analysed — it seems that the author conducted the main analysis at four weeks to 'gain' more data.

Selective reporting (reporting bias)Low riskComment: based on study report, protocol not obtained.

Other biasUnclear riskComment: there was some baseline imbalance in wound duration with 4.9 ± 7.8 months in alginate group vs 9.1 ± 13.1 months in Vaseline gauze group.
Funded by a commercial company.

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Agas 2006Study did not randomise participants.

Altman 1993No single, identifiable dressing type evaluated

Alvarez 2003The dressing groups evaluated in this study were not alginate dressings.

Apelqvist 1990Relevant outcome data are not reported: study outcome was limited to change in size of necrotic material on the wound. Study authors were unable to provide the original healing outcome data.

Apelqvist 1996No single, identifiable dressing type evaluated.

Apelqvist 2004No single, identifiable dressing type evaluated.

Armstrong 2004No single, identifiable dressing type evaluated.

Belcaro 2010The dressing groups evaluated in this study were not alginate dressings.

Blackman 1994The dressing groups evaluated in this study were not alginate dressings.

Bogaert 2004Study did not randomise participants.

Bradshaw 1989Trial stopped after recruiting six participants. No data presented. Authors not contacted for healing data.

Caravaggi 2003Other intervention, not dressings, differed between trial arms.

Chang 2000Study did not include diabetic foot ulcers.

Chauhan 2003Other intervention, not dressings, differ between trial arms

Chirwa 2010Study did not randomise participants.

Clever 1996The dressing groups evaluated in this study were not alginate dressings.

Cuevas 2007No single, identifiable dressing type evaluated.

D'Hemecourt 1998The dressing groups evaluated in this study were not alginate dressings.

Dash 2009Other intervention, not dressings, differ between trial arms

Diehm 2005Study did not randomise participants.

Driver 2006Other intervention, not dressings, differs between trial arms.

Edmonds 2009Other intervention, not dressings, differed between trial arms.

Eginton 2003No single, identifiable dressing type evaluated.

Etoz 2003Study did not randomise participants.

Farac 1999Author contacted: study not suitable for inclusion due to data quality issues.

Foo 2004The dressing groups evaluated in this study were not alginate dressings.

Foster 1999Other intervention, not dressings, differed between trial arms.

Gao 2007Other intervention, not dressings, differed between trial arms.

Gentzkow 1996Other intervention, not dressings, differed between trial arms.

Gottrup 2011The dressing groups evaluated in this study were not alginate dressings.

Hanft 2002Other intervention, not dressings, differed between trial arms.

Jeffcoate 2009The dressing groups evaluated in this study were not alginate dressings.

Jeffery 2008Study did not randomise participants.

Jensen 1998The dressing groups evaluated in this study were not alginate dressings.

Kordestani 2008The dressing groups evaluated in this study were not alginate dressings.

Landsman 2010Other intervention, not dressings, differed between trial arms.

Lazaro-Martinez 2007No single, identifiable dressing type evaluated.

Lipkin 2003Other intervention, not dressings, differed between trial arms.

Markevich 2000The dressing groups evaluated in this study were not alginate dressings.

Marston 2001Other intervention, not dressings, differed between trial arms.

Mazzone 1993The dressing groups evaluated in this study were not alginate dressings.

McCallon 2000Study did not randomise participants.

Mody 2008Study did not include diabetic foot ulcers.

Moretti 2009Other intervention, not dressings, differed between trial arms.

Mueller 1989Other intervention, not dressings, differed between trial arms.

Mulder 1994The dressing groups evaluated in this study were not alginate dressings.

Munter 2006The dressing groups evaluated in this study were not alginate dressings.

Novinscak 2010No single, identifiable dressing type evaluated.

Ogce 2007The dressing groups evaluated in this study were not alginate dressings.

Palao i Domenech 2008The dressing groups evaluated in this study were not alginate dressings.

Parish 2009Other intervention, not dressings, differed between trial arms.

Pham 1999Other intervention, not dressings, differed between trial arms.

Piaggesi 1997Study did not randomise participants.

Piaggesi 2001The dressing groups evaluated in this study were not alginate dressings.

Reyzelman 2009No single, identifiable dressing type evaluated.

Roberts 2001The dressing groups evaluated in this study were not alginate dressings.

Robson 2005Other intervention, not dressings, differed between trial arms.

Robson 2009Study did not include diabetic foot ulcers.

Sabolinski 2000Other intervention, not dressings, differed between trial arms.

Sabolinski 2001Other intervention, not dressings, differed between trial arms.

Shaw 2010Other intervention, not dressings, differed between trial arms.

Shukrimi 2008Other intervention, not dressings, differed between trial arms.

Sibbald 2011The dressing groups evaluated in this study were not alginate dressings.

Solway 2011Study did not randomise participants.

Steed 1992Other intervention, not dressings, differed between trial arms.

Steed 1995Other intervention, not dressings, differed between trial arms.

Steed 1996Other intervention, not dressings, differed between trial arms.

Subrahmanyam 1993The dressing groups evaluated in this study were not alginate dressings

Teot 2008The dressing groups evaluated in this study were not alginate dressings.

Trial 2010The dressing groups evaluated in this study were not alginate dressings.

Turns 2012Study did not randomise participants

Urbaneie 1999No single, identifiable dressing type evaluated.

Vandeputte 1997The dressing groups evaluated in this study were not alginate dressings.

Varma 2006No single, identifiable dressing type evaluated.

Veves 2001Other intervention, not dressings, differed between trial arms.

Veves 2002The dressing groups evaluated in this study were not alginate dressings.

Whalley 2001The dressings groups evaluated in this study were not alginate dressings.

Woo 2010The dressing groups evaluated in this study were not alginate dressings.

Yao 2007Other intervention, not dressings, differed between trial arms.

Zimny 2003Other intervention, not dressings, differed between trial arms.

 
Comparison 1. Alginate dressing compared with basic wound contact dressing

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Number of ulcers healed2114Risk Ratio (M-H, Fixed, 95% CI)1.09 [0.66, 1.80]

 
Comparison 2. Alginate dressings compared with foam dressings

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Number of ulcers healed250Risk Ratio (M-H, Fixed, 95% CI)0.67 [0.41, 1.08]

 
Comparison 3. Silver hydrocolloid dressing compared with alginate dressing

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Number of ulcers healed1Risk Ratio (M-H, Fixed, 95% CI)Subtotals only

 
Comparison 4. Trial data

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Trial dataOther dataNo numeric data

 
Analysis 4.1 Comparison 4 Trial data, Outcome 1 Trial data.
Trial data

StudyGroupsPrimary outcome: ulcer healing (SD = standard deviation)Secondary: health-related quality of lifeNumber and level of amputationsAdverse events, including painCost (SD = standard deviation)Ulcer recurrence

Ahroni 1993Group A (n = 20): two layers of calcium-alginate dressing;
Group B (n = 19): single layer of dry, fine mesh gauze.
Number of ulcers healed at 4 weeks:
Group A: 5
Group B: 7
Number of ulcers healed post 4-week follow-up:
Group A: 12
Group B: 14
Healing rate mm2/day (SD)(duration of measurements unclear):
Group A: (data from 5 participants missing): area, -2.19 (4.0); linear: 0.094 (0.147);
Group B: (data from 3 participants missing): area, -2.04 (2.61); linear: 0.084 (0.100).
Relative odds of non-healing (Group A vs Group B, adjusted for ulcer duration):
1.2 (CI not presented).
not reported(All post 4-week follow-up period):
Group A: 2
Group B: 2.
Within 4-week follow-up
Group A: hospitalised due to foot infection for parenteral antibiotics = 1, hospitalised for septicaemia = 1, treated with oral antibiotics = 3.
Group B: hospitalised due to foot infection for parenteral antibiotics = 1, treated with oral antibiotics = 2.
Post 4-week follow-up
Group A: 1 death;
Group B: 1 death.
not reportednot reported

Baker 1993Group A (n = 10): calcium alginate dressing;

Group B (n = 10): foam dressing.
Ulcer healing:
Number of ulcers healed at 12 weeks
Group A: 4

Group B: 9
Median healing time (days)
Group A: median time to healing not reached by 84 days

Group B: 28
Cox's proportional hazards model adjusted for initial ulcer size and duration of ulcer at baseline and treatment effect gave a hazard ratio of 4.04 in favour of foam dressing (95% CI 1.18 to 13.84).
not reportednot reported.
not reported.
not reportednot reported

Donaghue 1998Group A (n = 50): collagen-alginate dressing (Fibracol, Johnson & Johnson Medical);
Group B (n = 25): saline-moistened gauze.
Number of ulcers healed:
Group A: 24
Group B: 9
Mean time to healing in weeks (SD):
Group A: 6.2 (0.4)
Group B: 5.8 (0.4)
Reduction in wound area
75% or greater reduction in wound area:
Group A: 39
Group B: 15
Mean time to 75% healing in weeks (SD):
Group A: 3.46 (0.4)
Group B: 3.72 (0.5)
not reportednot reportedNumber of adverse events:
6 patients in total from both groups were not listed and reported for both groups separately.
not reportednot reported

Foster 1994Group A (n = 15): Calcium-alginate dressing;

Group B (n = 15): Foam dressing.
Number of ulcers healed:
Group A: 8

Group B: 9
Ulcers improved (not defined):
Group A: 3

Group B: 6
Median time to healing (days) (K-M plot presented but no median time to healing or HR from a Cox's Proportional Hazards analysis presented. The median time to healing was estimated by the reviewer author from the graph).
Group A: 42

Group B: 40
not reportednot reportedGroup A: severe pain = 1; dressings plugged a plantar lesion, preventing free drainage of exudate = 3  (1 developed cellulitis);

Group B: 0 .
not reportednot reported

Jude 2007Group A (n = 67): calcium-alginate dressing;    

Group B (n = 67): fibrous-hydrocolloid (hydrofibre) dressing with 1.2% ionic silver.
Number of ulcers healed in 8 weeks:
Group A:15

Group B: 21
Velocity of healing cm2/week (SD):
Group A: 0.26 (0.90) (n = 61)

Group B: 0.29 (0.33) (n = 61).
Velocity of healing as % per week (SD):
Group A: 10.0 (15.5)  (n = 61)  

Group B: 11.6 (17.7) (n = 61)   
Mean time in days to healing (SD):
Group A: 57.7 (1.7) 

Group B: 52.6 (1.8)                                                       
Reduction in ulcer area in 8 weeks:
Group A: 60.5 (42.7)

Group B: 58.1 (53.1)
Reduction in ulcer depth (cm) at 8 weeks (SD):
Group A:  0.13 (0.37)   

Group B:  0.25 (0.49)   
not reportednot reported     
Group A: 26 participants experienced adverse event: death = 1; infection = 8. 13 participants discontinued treatment due to adverse events.        

Group B: 25 participants experienced one or more events: death = 1; infection = 14. 8 participants discontinued treatment due to AE.                                         
Mean number of dressing changes during study:
Group A: 20.8     

Group B: 21.9  
not reported

Lalau 2002Group A (n = 39): calcium-alginate dressing;
Group B (n = 38): Vaseline gauze.
% of ulcers with granulated tissue over 75% of wound area and 40% decrease in wound surface area (not clear whether this was at 4 or 6 weeks):
Group A: 42.8
Group B: 28.5
Mean change in wound area at 4 weeks (SD) :
Group A: -35.7 (30.7)        
Group B: -34.9 (41.1)            
not reportednot reportedPain on dressing change removal (self-reported using a 10 cm visual analogue scale not reported whether 0 equalled no pain and 10 highest pain, or not) (SD):
Group A: 0.3 (0.1)       
Group B: 1.8 (0.6)   
Other events:
Group A: 4 participants experienced adverse events: osteitis = 1, osteoarthritis = 1, cardiac arrhyhtmia = 1, fatal myocardial infraction = 1).
Group B: 6 participants experienced adverse events: osteitis = 1, wound infection = 2, aggravation of arteriopathy = 1, occurrence of renal failure = 1, fatal pulmonary embolism = 1.                  
Total number of dressing changes (SD):
Group A: 20 (1)
Group B: 23 (1)      
not reported

 
Summary of findings for the main comparison. Alginate dressing compared to basic wound contact dressing for healing diabetic foot ulcers

Alginate dressing compared to basic wound contact dressing for healing diabetic foot ulcers

Patient or population: patients with
Settings: Any
Intervention: Alginate dressing
Comparison: basic wound contact dressing

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments

Assumed riskCorresponding risk

Basic wound contact dressingAlginate dressing

Number of ulcers healedLow1 RR 1.09
(0.66 to 1.8)
114
(2 studies)
⊕⊕⊝⊝
low2,3

340 per 1000371 per 1000
(224 to 612)

Moderate1

530 per 1000578 per 1000
(350 to 954)

High1

650 per 1000708 per 1000
(429 to 1000)

HRQoL - not measuredSee commentSee commentNot estimable-See commentFoot ulcers in people with diabetes adversely affect quality of life however no study measured (or reported) this.

Adverse eventsSee commentSee commentNot estimable0
(0)
See commentReporting of adverse events appeared to be ad hoc and the number of events were extremely small.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 1 Baseline risk of healing obtained from external source in which data from 27,630 patients with a diabetic neuropathic foot ulcer was used to develop a simple prognostic model to predict likelihood of ulcer healing (Margolis DJ, Allen-Taylor L, Hoffstad O, Berlin JA. Diabetic neuropathic foot ulcers: predicting which ones will not heal. Am J Med. 2003;115:627-31). It is important to note that given an outcome of ulcer healing, low risk refers to a low risk of healing and thus reflects the most severe patient populations. Conversely high risk refers to a high risk of healing.
2 Both studies at unclear or high risk of bias
3 Studies were small, total number of participants 114 with only 40% achieving healing; this is an underpowered comparison.
 
Summary of findings 2. Alginate dressings compared to foam dressings for healing diabetic foot ulcers

Alginate dressings compared to foam dressings for healing diabetic foot ulcers

Patient or population: patients with healing diabetic foot ulcers
Settings: Any
Intervention: Alginate dressings
Comparison: foam dressings

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No of Participants
(studies)
Quality of the evidence
(GRADE)
Comments

Assumed riskCorresponding risk

Foam dressingsAlginate dressings

Number of ulcers healedLow1 RR 0.67
(0.41 to 1.08)
50
(2 studies)
⊕⊕⊝⊝
low2,3

340 per 1000228 per 1000
(139 to 367)

Moderate1

530 per 1000355 per 1000
(217 to 572)

High1

650 per 1000435 per 1000
(266 to 702)

HRQoL - not measuredSee commentSee commentNot estimable-See commentFoot ulcers in people with diabetes adversely affect quality of life however no study measured (or reported) this.

Adverse events See commentSee commentNot estimable0
(0)
See commentReporting of adverse events appeared to be ad hoc and the number of events were extremely small and only reported in one trial.

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio;

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 1 Baseline risk of healing obtained from external source in which data from 27,630 patients with a diabetic neuropathic foot ulcer was used to develop a simple prognostic model to predict likelihood of ulcer healing (Margolis DJ, Allen-Taylor L, Hoffstad O, Berlin JA. Diabetic neuropathic foot ulcers: predicting which ones will not heal. Am J Med. 2003;115:627-31). It is important to note that given an outcome of ulcer healing, low risk refers to a low risk of healing and thus reflects the most severe patient populations. Conversely high risk refers to a high risk of healing.
2 Both studies overall at unclear risk of bias, however one study was at low risk of bias for one domain (random sequence generation).
3 Only 50 participants were included in this comparison.
 
Table 1. Summary of studies

First AuthorGroup A Group B Duration of follow-up% healed data

Ahroni 1993Calcium-alginate dressing (Sorbsan, Aspen Medical)Dry, fine mesh gauze (Owens Non-Adherent dressing)4 weeksYes

Baker 1993Calcium-alginate dressing (Sorbsan, Aspen Medical)Foam dressing (Allevyn, Smith and Nephew )12 weeksYes

Donaghue 1998Collagen-alginate dressing (Fibracol, Johnson & Johnson Medical)Saline moistened gauze8 weeksYes

Foster 1994Calcium-alginate dressing (Kaltostat, ConvaTec)Foam dressing (Allevyn, Smith and Nephew )8 weeksYes

Jude 2007Calcium-alginate dressing (Alosteril, Smith and Nephew)Fibrous-hydrocolloid (hydrofibre) dressing with 1.2% ionic silver (Aquacel Ag, ConvaTec)8 weeksYes

Lalau 2002Calcium-alginate dressing (Algosteril, Smith and Nephew)Vaseline gauze (Vaselitulle, Solvay Pharma)4 weeksNo