Table 4

Multinomial and ordinal regression models for individually fitted baseline factors

OR (95%  CI)AIC§Reduction in
−2 Log L
dfP value
Multinomial summary of isolatesBoth swab and tissue report the same pathogens.
Null model941.29
Ulcer type*945.721.57030.666
 Any ischaemic versus neuropathic onlySwab>pathogens compared with the tissue1.03 (0.48 to 2.20)
 Any ischaemic versus neuropathic onlyTissue>pathogens compared with the swab0.86 (0.53 to 1.40)
 Any ischaemic versus neuropathic onlySwab and tissue report totally different pathogens.0.68 (0.35 to 1.31)
Ulcer grade949.164.12560.660
 Grade 2 versus grade 1Swab>pathogens compared with the tissue0.68 (0.26 to 1.78)
 Grade 2 versus grade 1Tissue>pathogens compared with the swab1.08 (0.60 to 1.93)
 Grade 2 versus grade 1Swab and tissue report totally different pathogens.1.14 (0.51 to 2.54)
 Grade 3/4/5 versus grade 1Swab>pathogens compared with the tissue1.28 (0.52 to 3.11)
 Grade 3/4/5 versus grade 1Tissue>pathogens compared with the swab1.60 (0.87 to 2.95)
 Grade 3/4/5 versus grade 1Swab and tissue report totally different pathogens.1.55 (0.69 to 3.45)
Previous antibiotic therapy*946.281.00530.800
 Yes versus noSwab>pathogens compared with the tissue0.80 (0.36 to 1.80)
 Yes versus noTissue>pathogens compared with the swab1.14 (0.69 to 1.89)
 Yes versus noSwab and tissue report totally different pathogens.1.10 (0.56 to 2.16)
Antimicrobial dressing*943.443.85030.278
 Yes versus noSwab>pathogens compared with the tissue1.13 (0.51 to 2.51)
 Yes versus noTissue>pathogens compared with the swab0.69 (0.40 to 1.19)
 Yes versus noSwab and tissue report totally different pathogens.1.38 (0.66 to 2.89)
Wound duration (median split)*941.485.80230.121
 <56 days vs ≥56 daysSwab>pathogens compared with the tissue0.94 (0.43 to 2.04)
 <56 days vs ≥56 daysTissue>pathogens compared with the swab1.75 (1.08 to 2.86)†
 <56 days vs ≥56 daysSwab and tissue report totally different pathogens.1.14 (0.59 to 2.17)
Log wound duration (continuous)*944.972.31830.509
Swab>pathogens compared with the tissue0.95 (0.72 to 1.25)
Tissue>pathogens compared with the swab0.88 (0.74 to 1.04)
Swab and tissue report totally different pathogens.0.93 (0.74 to 1.18)
Ordinal summary of isolates
Null model917.72
Ulcer type*: any ischaemic versus neuropathic only0.90 (0.61 to 1.33)919.450.27110.603
Ulcer grade920.161.55920.459
 Grade 2 versus grade 11.33 (0.82 to 2.15)
 Grade 3/4/5 versus grade 11.27 (0.78 to 2.07)
Previous antibiotic therapy*: yes versus no1.25 (0.81 to 1.91)918.561.15410.283
Antimicrobial dressing*: yes versus no0.76 (0.49 to 1.18)918.161.55310.213
Wound duration (median split)*: <56 days vs ≥56 days1.56 (1.05 to 2.33)914.625.09710.024‡
Log wound duration (continuous)*0.92 (0.80 to 1.05)918.151.57110.210
  • Based on the evaluable population n=395.

  • *Factors with missing data from the 28 (7.1%) patients with at least one missing data item.

  • ‡Significant at the 5% level.

  • §Smaller is better.

  • AIC, Akaike information criterion.