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Pathophysiology/complications
Recurrence rates suggest delayed identification of plantar ulceration for patients in diabetic foot remission
  1. Brian J Petersen1,
  2. Sicco A Bus2,
  3. Gary M Rothenberg3,
  4. David R Linders1,
  5. Lawrence A Lavery4,
  6. David G Armstrong5
  1. 1Podimetrics Inc, Somerville, Massachusetts, USA
  2. 2Department of Rehabilitation Medicine, University of Amsterdam, Amsterdam, Noord-Holland, Netherlands
  3. 3Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
  4. 4Department of Plastic Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
  5. 5Department of Surgery, USC Keck School of Medicine, Los Angeles, California, USA
  1. Correspondence to Mr Brian J Petersen; authors{at}podiography.org

Abstract

Introduction Foot ulcers are a common and costly complication of diabetes, and delays in treatment can result in impaired healing, infection, hospitalization, and lower extremity amputation.

Research design and methods We aimed to determine whether patterns in plantar diabetic foot ulcer (DFU) recurrence coincided with typical intervals between routine preventive care appointments, which would suggest that delays exist between ulcer development and identification. We completed an analysis of existing data from two multicenter studies in 300 total participants. We analyzed unadjusted counts of DFU binned in weekly intervals and defined ‘exam periods’ as intervals from 2 to 4 weeks, from 6 to 8 weeks, within 1 week of 3 months and within 1 week of 6 months. We tested whether recurrence rates during exam periods were equivalent to rates outside exam periods. We estimated the delay between DFU development and DFU identification such that the rate of development would have been constant.

Results During exam periods, a total of 43 DFUs were identified (43/86=50%) despite the fact that these periods represent only 23.5% of follow-up in aggregate. Accounting for censoring, the annualized incidence during exam periods was 0.68 DFU/year (CI 0.48 to 0.89) in contrast to 0.25 DFU/year (CI 0.18 to 0.32) outside exam periods (incidence ratio=2.8, CI 1.8 to 4.3). We estimated delays between DFU occurrence and identification to average 15.3 days (IQR 7.4–23.7 days).

Conclusions These findings have potential implications for practice, particularly related to the value of telehealth and in-home monitoring of patients in diabetic foot remission. Additionally, there are implications for study design, which should consider the impact of interval censoring and attempt to control for confounders related to frequency and timing of exams.

  • diabetic foot
  • diabetic foot ulcer
  • recurrence
  • epidemiology
  • diabetic foot remission
http://creativecommons.org/licenses/by-nc/4.0/

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.

https://doi.org/10.1136/bmjdrc-2020-001697

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    Footnotes

    • Contributors BJP and DRL: concept and design, analysis of data, interpretation of data and preparation of the manuscript. SAB: concept and design, collection of data, interpretation of data and preparation of the manuscript. GMR: interpretation of data, collection of data, preparation of the manuscript. LAL and DGA: concept and design, interpretation of data and preparation of the manuscript. All authors contributed to critically revise the manuscript and have given final approval of the version to be published.

    • Funding There is no funding to report for the secondary analysis of existing data. Funding details for the two studies on which this research is based are cited in the original publications.

    • Competing interests BJP and DRL are employees and shareholders of Podimetrics, Inc. GMR is a consulting medical director for Podimetrics Inc. LAL and DGA are on the scientific advisory board of Podimetrics Inc. SAB reports no competing interests.

    • Patient consent for publication Not required.

    • Ethics approval This study is a secondary analysis of existing deidentified data from two trials which received ethics approval. Informed consent for these trials allowed use of data collected for research purposes, including secondary analyses. Ethics approval details are cited in the original publications for these two studies. The first study, Bus et al, was approved by the medical ethics committees of all 10 participating centers. All participants gave informed consent. The second study, Frykberg et al, was approved by the New England Institutional Review Board and local review boards as required by each site. All participants gave informed consent.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data availability statement Data and code are available for research purposes upon reasonable request to the corresponding author.