Differentiating diabetic foot ulcers that are unlikely to heal by 12 weeks following achieving 50% percent area reduction at 4 weeks

Abstract

This retrospective analysis included intent-to-treat control patient data from two published, randomised, diabetic foot ulcer (DFU) trials in an effort to differentiate ulcers that are unlikely to heal by 12 weeks despite early healing progress [≥50% percent area reduction (PAR) at 4 weeks]. Predicted and actual wound area trajectories in DFUs that achieved early healing progress were analysed from weeks 5 to 12 and compared for ulcers that did and did not heal at 12 weeks. In 120 patients who achieved ≥50% PAR by week 4, 62 (52%) failed to heal by 12 weeks. Deviations from the predicted healing course were evident by 6 weeks for non healing ulcers. A 2-week delay in healing significantly lowered healing rates (P = 0·001). For DFUs with ≥50% PAR at 4 weeks, those achieving ≥90% versus <90% PAR at 8 weeks had a 2·7-fold higher healing rate at 12 weeks (P = 0·001). A PAR of <90% at 8 weeks provided a negative predictive value for DFU healing at 12 weeks of 82%. For ulcers that fail to progress or worsen from weeks 4 to 6, and those that fail to achieve 90% PAR at 8 weeks, reevaluation of the wound and its treatment is recommended.

© 2011 The Authors. © 2011 Blackwell Publishing Ltd and Medicalhelplines.com Inc.

Figures

Figure 1

Scatter plots of median ulcer area versus time from diabetic foot ulcers that healed and did not heal by 12 weeks. Healed at 12 weeks (n = 58) (A). Non healed at 12 weeks (n = 62) (B). Fitted curves are exponential functions with negative constants (at = a0 *e−b*t). Fitting and analysis conducted via non linear least squares regression.

Figure 2

Percent area reduction (PAR) for diabetic foot ulcers (DFUs) that achieved ≥50% PAR at week 4 stratified by healed and non healed DFUs by week 12 (n = 120). Median PAR from week 5 presented as line plots of PAR (1st and 3rd quartile indicated in shaded areas) stratified by healed and non healed DFUs at week 12.

Figure 3

Healing rate at week 12 stratified by patients who achieved ≥90% (n = 19) and <90% (n = 10) percent area reduction (PAR) at week 8. After achieving ≥50% closure at week 4, a total of 51% of patients had diabetic foot ulcers (DFUs) that healed by week 12 after achieving ≥90% PAR at week 8 compared with 19% of patients with DFUs that achieved <90% PAR at week 8 (P = 0·001). Error bars represent 95% confidence intervals for the proportions.

Figure 4

Number of patients and percent of healed wounds reported for patients who qualified for the various prognostic groups. PAR, percent area reduction.
*Total does not add to 250 patients because data for 3 patients are not reported after week 4.