Table 1.
HRs from survival analysis (Cox regression) for the association of individual factors with failure
| Variable/category | n | Number failing | Hazard ratio | 95% CI | P |
|---|---|---|---|---|---|
| Gender | |||||
| female | 50 | 10 | 1 | ||
| male | 62 | 10 | 0.7 | 0.30–1.73 | 0.47 |
| Age (years) | |||||
| <40 | 2 | 0 | — | ||
| 40–49 | 2 | 1 | — | ||
| 50–59 | 22 | 4 | 1 | ||
| 60–69 | 34 | 5 | 0.8 | 0.21–3 | 0.75 |
| 70–79 | 35 | 7 | 1.2 | 0.35–4.1 | 0.86 |
| 80–89 | 17 | 3 | 1.1 | 0.26–5.13 | 0.92 |
| Co-morbidity | |||||
| none | 45 | 4 | 1 | ||
| one or more | 66 | 15 | 2.7 | 0.91–8.3 | 0.07 |
| unknown | 1 | 1 | |||
| Time from implant to debridement (days) | |||||
| <90 | 77 | 9 | 1 | ||
| ≥90 | 35 | 11 | 3.0 | 1.2–7.2 | 0.016 |
| Time from presentation to debridement (days) | |||||
| <3 | 71 | 9 | 1 | ||
| 3–14 | 25 | 6 | 0.77 | 0.24–2.5 | 0.67 |
| >14 | 16 | 5 | 0.36 | 0.12–1.0 | 0.07 |
| Arthroplasty | |||||
| primary implant | 86 | 11 | 1 | ||
| revised implant | 26 | 9 | 2.6 | 1.1–6.3 | 0.031 |
| Surgical debridement | |||||
| open debridement | 97 | 12 | 1 | ||
| arthroscopy | 15 | 8 | 5.4 | 2.2–13 | <0.0005 |
| Joint | |||||
| hip | 52 | 7 | 1 | ||
| knee | 51 | 13 | 0.47 | 0.19–1.18 | 0.10 |
| ankle | 3 | 0 | — | ||
| shoulder | 2 | 0 | — | ||
| elbow | 4 | 0 | — | ||
| Surgical findings | |||||
| no pus at surgery | 54 | 8 | 1 | ||
| pus at surgery | 48 | 1 | 1.5 | 0.59–3.65 | 0.41 |
| unknown | 10 | 11 | — | ||
| Number of debridements | |||||
| single procedure | 88 | 14 | 1 | ||
| multiple procedures | 24 | 6 | 1.8 | 0.68–4.7 | 0.24 |
| Microbiologya | |||||
| MRSA | 9 | 3 | 2.0 | 0.59–7 | 0.26 |
| MSSA | 39 | 10 | 1.8 | 0.71–4.4 | 0.21 |
| CoNS | 26 | 5 | 1.0 | 0.36–2.8 | 0.99 |
| S. aureus | 47 | 13 | 2.6 | 0.97–6.9 | 0.052 |
| Intravenous antibiotics | |||||
| <28 days | 26 | 8 | 1 | ||
| ≥28 days | 86 | 12 | 0.41 | 0.16–0.99 | 0.050 |
MRSA, methicillin-resistant S. aureus; MSSA, methicillin-susceptible S. aureus; CoNS, coagulase-negative staphylococci.
aMultiple organisms can be isolated from one patient, hence the sum of n is >112.