Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial

Chris Bojke; Henrietta Konwea; E.  Andrea Nelson; Sarah T. Brown; Colin C. Everett; Angela Oates; Michael Backhouse; Howard Collier; Joanna Dennett; Rachael Gilberts; Benjamin A. Lipsky; Michelle M. Lister; Jane E. Nixon; David Russell; Tim Sloan; Fran Game; CODIFI2 Investigators

doi:10.1111/dme.15492

Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial

Chris Bojke^*, Henrietta Konwea, E. Andrea Nelson^*, Sarah T. Brown, Colin C. Everett, Angela Oates, Michael Backhouse, Howard Collier, Joanna Dennett, Rachael Gilberts, Benjamin A. Lipsky, Michelle M. Lister, Jane E. Nixon, David Russell, Tim Sloan, Fran Game, CODIFI2 Investigators

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

AIMS: To compare the cost-effectiveness of wound swabbing versus tissue sampling for infected diabetic foot ulcers.

METHODS: This multi-centre, Phase III, prospective, unblinded, two-arm parallel group, randomised controlled trial compared clinical (reported elsewhere) and economic outcomes of swab versus tissue sampling over a 52-104 week period. Resource use was logged using case record forms and patient questionnaire at weeks 4, 12, 26, 39, 52 and 104, costed using laboratory and published sources from the UK NHS perspective, at 2021/2022 price-year. EQ-5D-3L questionnaires issued at these time points were used to derive quality-adjusted life-years (QALYs). To account for imbalances such as age, a regression-based approach was used to estimate survival, expected costs and QALYs between the sampling arms. Available case analysis (ACA) and multiple imputation methods were applied for self reported missing data, and ACA for researcher-collected data (survival, hospitalisations and antibiotic use). Probabilistic sensitivity analysis was used to assess the uncertainty of economic results.

RESULTS: We recruited 149 participants (75 swab, 74 tissue) from 21 UK sites, between 07 May 2019 and 28 April 2022 (last follow-up 28 April 2023). Planned sample size was 730 participants, for 90% power to detect 12.5% difference in healing at 52 weeks, but the trial stopped early due to low recruitment. Expected QALYs in the swab-sampling arm were greater than in the tissue-sampling arm at weeks 26, 52 and 104. The cost of tissue sampling was greater than of swabbing when including antibiotics and hospitalisation. Swab sampling participants had higher QALYs and lower costs across weeks 26-52, reducing slightly by week 104.

CONCLUSIONS: Because of higher costs, lower QALYs and lack of evidence of benefit, potentially due to the trial being underpowered, tissue sampling was dominated by wound swabbing in the cost-effectiveness analysis.

Original language	English
Pages (from-to)	e15492
Number of pages	12
Journal	Diabetic Medicine
Early online date	27 Feb 2025
DOIs	https://doi.org/10.1111/dme.15492
Publication status	E-pub ahead of print - 27 Feb 2025

Keywords

antibacterial agents
cost-effectiveness analysis
diabetic foot
quality-adjusted life-years
randomised controlled trial
wound sampling

ASJC Scopus subject areas

Health Professions(all)
Immunology and Microbiology(all)
Medicine(all)

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Documents and Links

10.1111/dme.15492

Final published versionFinal published version, 676 KBLicence: CC BY

Cite this

Bojke, C., Konwea, H., Nelson, E. A., Brown, S. T., Everett, C. C., Oates, A., Backhouse, M., Collier, H., Dennett, J., Gilberts, R., Lipsky, B. A., Lister, M. M., Nixon, J. E., Russell, D., Sloan, T., Game, F., & CODIFI2 Investigators (2025). Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial. Diabetic Medicine, e15492. Advance online publication. https://doi.org/10.1111/dme.15492

@article{c1c9cc6110c8442b87e644a30936a77d,

title = "Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial",

abstract = "AIMS: To compare the cost-effectiveness of wound swabbing versus tissue sampling for infected diabetic foot ulcers.METHODS: This multi-centre, Phase III, prospective, unblinded, two-arm parallel group, randomised controlled trial compared clinical (reported elsewhere) and economic outcomes of swab versus tissue sampling over a 52-104 week period. Resource use was logged using case record forms and patient questionnaire at weeks 4, 12, 26, 39, 52 and 104, costed using laboratory and published sources from the UK NHS perspective, at 2021/2022 price-year. EQ-5D-3L questionnaires issued at these time points were used to derive quality-adjusted life-years (QALYs). To account for imbalances such as age, a regression-based approach was used to estimate survival, expected costs and QALYs between the sampling arms. Available case analysis (ACA) and multiple imputation methods were applied for self reported missing data, and ACA for researcher-collected data (survival, hospitalisations and antibiotic use). Probabilistic sensitivity analysis was used to assess the uncertainty of economic results.RESULTS: We recruited 149 participants (75 swab, 74 tissue) from 21 UK sites, between 07 May 2019 and 28 April 2022 (last follow-up 28 April 2023). Planned sample size was 730 participants, for 90% power to detect 12.5% difference in healing at 52 weeks, but the trial stopped early due to low recruitment. Expected QALYs in the swab-sampling arm were greater than in the tissue-sampling arm at weeks 26, 52 and 104. The cost of tissue sampling was greater than of swabbing when including antibiotics and hospitalisation. Swab sampling participants had higher QALYs and lower costs across weeks 26-52, reducing slightly by week 104.CONCLUSIONS: Because of higher costs, lower QALYs and lack of evidence of benefit, potentially due to the trial being underpowered, tissue sampling was dominated by wound swabbing in the cost-effectiveness analysis.",

keywords = "antibacterial agents, cost-effectiveness analysis, diabetic foot, quality-adjusted life-years, randomised controlled trial, wound sampling",

author = "Chris Bojke and Henrietta Konwea and Nelson, {E. Andrea} and Brown, {Sarah T.} and Everett, {Colin C.} and Angela Oates and Michael Backhouse and Howard Collier and Joanna Dennett and Rachael Gilberts and Lipsky, {Benjamin A.} and Lister, {Michelle M.} and Nixon, {Jane E.} and David Russell and Tim Sloan and Fran Game and {CODIFI2 Investigators}",

note = "{\textcopyright} 2025 The Author(s). Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.",

year = "2025",

month = feb,

day = "27",

doi = "10.1111/dme.15492",

language = "English",

pages = "e15492",

journal = "Diabetic Medicine",

issn = "0742-3071",

publisher = "Wiley-Blackwell Publishing Ltd",

}

Bojke, C, Konwea, H, Nelson, EA, Brown, ST, Everett, CC, Oates, A, Backhouse, M, Collier, H, Dennett, J, Gilberts, R, Lipsky, BA, Lister, MM, Nixon, JE, Russell, D, Sloan, T, Game, F & CODIFI2 Investigators 2025, 'Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial', Diabetic Medicine, pp. e15492. https://doi.org/10.1111/dme.15492

TY - JOUR

T1 - Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial

AU - Bojke, Chris

AU - Konwea, Henrietta

AU - Nelson, E. Andrea

AU - Brown, Sarah T.

AU - Everett, Colin C.

AU - Oates, Angela

AU - Backhouse, Michael

AU - Collier, Howard

AU - Dennett, Joanna

AU - Gilberts, Rachael

AU - Lipsky, Benjamin A.

AU - Lister, Michelle M.

AU - Nixon, Jane E.

AU - Russell, David

AU - Sloan, Tim

AU - Game, Fran

AU - CODIFI2 Investigators

PY - 2025/2/27

Y1 - 2025/2/27

N2 - AIMS: To compare the cost-effectiveness of wound swabbing versus tissue sampling for infected diabetic foot ulcers.METHODS: This multi-centre, Phase III, prospective, unblinded, two-arm parallel group, randomised controlled trial compared clinical (reported elsewhere) and economic outcomes of swab versus tissue sampling over a 52-104 week period. Resource use was logged using case record forms and patient questionnaire at weeks 4, 12, 26, 39, 52 and 104, costed using laboratory and published sources from the UK NHS perspective, at 2021/2022 price-year. EQ-5D-3L questionnaires issued at these time points were used to derive quality-adjusted life-years (QALYs). To account for imbalances such as age, a regression-based approach was used to estimate survival, expected costs and QALYs between the sampling arms. Available case analysis (ACA) and multiple imputation methods were applied for self reported missing data, and ACA for researcher-collected data (survival, hospitalisations and antibiotic use). Probabilistic sensitivity analysis was used to assess the uncertainty of economic results.RESULTS: We recruited 149 participants (75 swab, 74 tissue) from 21 UK sites, between 07 May 2019 and 28 April 2022 (last follow-up 28 April 2023). Planned sample size was 730 participants, for 90% power to detect 12.5% difference in healing at 52 weeks, but the trial stopped early due to low recruitment. Expected QALYs in the swab-sampling arm were greater than in the tissue-sampling arm at weeks 26, 52 and 104. The cost of tissue sampling was greater than of swabbing when including antibiotics and hospitalisation. Swab sampling participants had higher QALYs and lower costs across weeks 26-52, reducing slightly by week 104.CONCLUSIONS: Because of higher costs, lower QALYs and lack of evidence of benefit, potentially due to the trial being underpowered, tissue sampling was dominated by wound swabbing in the cost-effectiveness analysis.

AB - AIMS: To compare the cost-effectiveness of wound swabbing versus tissue sampling for infected diabetic foot ulcers.METHODS: This multi-centre, Phase III, prospective, unblinded, two-arm parallel group, randomised controlled trial compared clinical (reported elsewhere) and economic outcomes of swab versus tissue sampling over a 52-104 week period. Resource use was logged using case record forms and patient questionnaire at weeks 4, 12, 26, 39, 52 and 104, costed using laboratory and published sources from the UK NHS perspective, at 2021/2022 price-year. EQ-5D-3L questionnaires issued at these time points were used to derive quality-adjusted life-years (QALYs). To account for imbalances such as age, a regression-based approach was used to estimate survival, expected costs and QALYs between the sampling arms. Available case analysis (ACA) and multiple imputation methods were applied for self reported missing data, and ACA for researcher-collected data (survival, hospitalisations and antibiotic use). Probabilistic sensitivity analysis was used to assess the uncertainty of economic results.RESULTS: We recruited 149 participants (75 swab, 74 tissue) from 21 UK sites, between 07 May 2019 and 28 April 2022 (last follow-up 28 April 2023). Planned sample size was 730 participants, for 90% power to detect 12.5% difference in healing at 52 weeks, but the trial stopped early due to low recruitment. Expected QALYs in the swab-sampling arm were greater than in the tissue-sampling arm at weeks 26, 52 and 104. The cost of tissue sampling was greater than of swabbing when including antibiotics and hospitalisation. Swab sampling participants had higher QALYs and lower costs across weeks 26-52, reducing slightly by week 104.CONCLUSIONS: Because of higher costs, lower QALYs and lack of evidence of benefit, potentially due to the trial being underpowered, tissue sampling was dominated by wound swabbing in the cost-effectiveness analysis.

KW - antibacterial agents

KW - cost-effectiveness analysis

KW - diabetic foot

KW - quality-adjusted life-years

KW - randomised controlled trial

KW - wound sampling

U2 - 10.1111/dme.15492

DO - 10.1111/dme.15492

M3 - Article

C2 - 40013389

SN - 0742-3071

SP - e15492

JO - Diabetic Medicine

JF - Diabetic Medicine

ER -

Cost-effectiveness of swab versus tissue sampling for infected diabetic foot ulcers from the CODIFI2 randomised controlled trial

Abstract

Keywords

ASJC Scopus subject areas

UN SDGs

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