Table 1

Standardised mortality ratio (SMR) of studied patients compared with general population

SubgroupsPrimary hip replacementPrimary knee replacement
Number of patientsSMR (95% CI)Number of patientsSMR (95% CI)
Gender
 Female18 3360.90 (0.86 to 0.95)16 2050.76 (0.72 to 0.81)
 Male15 7970.93 (0.89 to 0.98)14 1360.82 (0.78 to 0.86)
Ethnicity
 European/others29 8530.88 (0.84 to 0.91)25 6920.77 (0.74 to 0.80)
 Māori36711.64 (1.43 to 1.89)23171.41 (1.20 to 1.66)
 Pacific4191.02 (0.62 to 1.68)13450.76 (0.58 to 1.00)
 Asian1900.95 (0.51 to 1.80)9870.58 (0.44 to 0.78)
Age (years)
 <405181.81 (0.48 to 6.89)524.72 (0.18 to 127.22)
 40–4921271.32 (0.84 to 2.06)7191.35 (0.63 to 2.92)
 50–5955151.37 (1.13 to 1.66)46811.11 (0.90 to 1.38)
 60–6999241.12 (1.02 to 1.23)10 1440.88 (0.80 to 0.97)
 70–7911 3000.84 (0.80 to 0.89)10 9280.74 (0.70 to 0.78)
 80+47490.88 (0.83 to 0.93)38170.79 (0.75 to 0.84)
Charlson Comorbidity Index
 029 6630.79 (0.76 to 0.82)25 5380.70 (0.67 to 0.73)
 122361.37 (1.24 to 1.52)22601.17 (1.05 to 1.30)
 215981.68 (1.45 to 1.95)18741.12 (0.96 to 1.30)
 3+6362.37 (1.97 to 2.85)6691.93 (1.59 to 2.35)
Year
 200531761.05 (0.97 to 1.13)29700.94 (0.87 to 1.01)
 200631491.04 (0.96 to 1.13)28350.86 (0.79 to 0.94)
 200735200.97 (0.90 to 1.06)31090.84 (0.76 to 0.92)
 200833120.98 (0.89 to 1.08)28280.79 (0.71 to 0.88)
 200934730.87 (0.78 to 0.97)30090.84 (0.75 to 0.95)
 201033560.79 (0.70 to 0.90)28490.66 (0.58 to 0.76)
 201133050.75 (0.65 to 0.87)29810.68 (0.58 to 0.80)
 201234260.72 (0.60 to 0.85)30970.49 (0.40 to 0.61)
 201335410.63 (0.50 to 0.78)30200.47 (0.36 to 0.60)
 201438750.62 (0.47 to 0.81)36430.46 (0.33 to 0.63)
Health network
 Northern89560.90 (0.83 to 0.96)99960.72 (0.67 to 0.77)
 Mid Central70400.96 (0.89 to 1.04)64480.82 (0.75 to 0.89)
 Midland83080.94 (0.88 to 1.01)68340.84 (0.78 to 0.91)
 Southern98070.88 (0.83 to 0.95)70460.83 (0.77 to 0.89)
 Unknown221.21 (0.25 to 5.84)170.47 (0.05 to 4.65)
Number of same type of surgeries in 2005–2017
 128 8040.98 (0.94 to 1.02)24 1280.87 (0.83 to 0.91)
 253290.57 (0.51 to 0.64)62130.52 (0.47 to 0.57)
Total34 1330.92 (0.89 to 0.95)33 8250.79 (0.76 to 0.82)