Table 3

Adjusted HRs for 30-day mortality by amputation type and further stratified by covariates

Major amputation 30-day mortality adjusted HR (95% CI)1Minor amputation 30-day mortality adjusted HR (95% CI)1
Sex
 FemaleReferenceReference
 Male0.87 (0.68–1.11)1.02 (0.68–1.52)
Age (years)
 0–2422
 25–490.92 (0.58–1.48)0.58 (0.22–1.54)
 50–64ReferenceReference
 65–740.96 (0.68–1.34)1.94 (1.09–3.46)
 ≥751.59 (1.15–2.18)4.15 (2.45–7.03)
Ethnicity
 European/otherReferenceReference
 Māori1.46 (1.08–1.98)1.73 (1.02–2.94)
 Pacific1.11 (0.68–1.83)1.74 (0.89–3.42)
 Asian1.75 (0.88–3.49)1.49 (0.46–4.81)
Deprivation (NZDep)
 1–2ReferenceReference
 3–40.73 (0.42–1.28)0.72 (0.26–1.98)
 5–60.89 (0.54–1.48)1.32 (0.58–3.04)
 7–80.97 (0.6–1.56)1.75 (0.81–3.81)
 9–100.9 (0.56–1.46)1.79 (0.81–3.92)
Rurality (URPC)
 UrbanReferenceReference
 Independent urban0.88 (0.63–1.23)1.2 (0.75–1.93)
 Rural1.24 (0.82–1.87)1.54 (0.84–2.83)
Hospital volume (amputations/year)
 ≥500ReferenceReference
 100–4990.99 (0.77–1.29)1.14 (0.75–1.72)
 <1000.86 (0.52–1.4)0.78 (0.38–1.58)
Admission type
 Acute1.44 (1.07–1.93)1.43 (0.92–2.22)
 ElectiveReferenceReference
Comorbidity (M3 index)3
 0ReferenceReference
 11.03 (0.78–1.35)0.99 (0.64–1.52)
 21.1 (0.78–1.55)0.91 (0.54–1.55)
 31.21 (0.85–1.73)0.8 (0.45–1.43)
  • 1Adjusted for all other covariates.

  • 2Insufficient data to calculate HRs.

  • 3HR at the given splined M3 index score value (e.g., score of 1 vs. score of 0).