Frailty model of time to all-cause mortality following hip or knee arthroplasty with NDVI quartiles (hip and knee: number of participants=14 010, number of observations=149 523; hip: number of participants=7449, number of observations=78 501; knee: number of participants=6558, number of observations=71 022)†. The ethnicity reference group is a composite of all ethnicities other than European NZ or Māori
| Variables | Hip and knee | Hip | Knee | |||
| HR | 95% CI | OR | 95% CI | OR | 95% CI | |
| Age (years) | 1.090*** | 1.086 to 1.094 | 1.083*** | 1.078 to 1.089 | 1.098*** | 1.091 to 1.105 |
| Female | 0.714*** | 0.670 to 0.761 | 0.735*** | 0.674 to 0.801 | 0.666*** | 0.605 to 0.734 |
| Ethnicity: European NZ | 1.305*** | 1.147 to 1.484 | 1.272** | 1.058 to 1.529 | 1.277*** | 1.066 to 1.53 |
| Ethnicity: Māori | 2.124*** | 1.796 to 2.513 | 1.895*** | 1.504 to 2.386 | 2.276*** | 1.771 to 2.926 |
| NZDep | 1.012* | 1.000 to 1.024 | 1.021** | 1.005 to 1.038 | 0.998 | 0.98 to 1.016 |
| Chronic condition: COPD | 1.448*** | 1.325 to 1.583 | 1.41*** | 1.249 to 1.591 | 1.476*** | 1.292 to 1.686 |
| Chronic condition: acute MI | 1.443*** | 1.295 to 1.608 | 1.383*** | 1.199 to 1.596 | 1.476*** | 1.249 to 1.744 |
| Chronic condition: cancer | 1.489*** | 1.361 to 1.629 | 1.602*** | 1.425 to 1.8 | 1.33*** | 1.154 to 1.532 |
| Chronic condition: stroke | 1.568*** | 1.347 to 1.826 | 1.702*** | 1.394 to 2.079 | 1.384*** | 1.092 to 1.753 |
| Chronic condition: diabetes | 1.307*** | 1.204 to 1.418 | 1.275*** | 1.139 to 1.427 | 1.348*** | 1.196 to 1.519 |
| Chronic condition: traumatic brain injury | 1.300* | 0.995 to 1.699 | 1.194 | 0.836 to 1.705 | 1.464* | 0.976 to 2.195 |
| Opioid scripts 12 months presurgery | 1.005*** | 1.004 to 1.006 | 1.018*** | 1.014 to 1.023 | 1.004*** | 1.002 to 1.006 |
| NDVI (standardised) quartile 2 | 0.933 | 0.856 to 1.017 | 0.988 | 0.881 to 1.107 | 0.852* | 0.747 to 0.971 |
| NDVI (standardised) quartile 3 | 0.953 | 0.873 to 1.041 | 0.926 | 0.823 to 1.042 | 0.974 | 0.854 to 1.111 |
| NDVI (standardised) quartile 4 | 0.884** | 0.804 to 0.971 | 0.863** | 0.762 to 0.978 | 0.902 | 0.784 to 1.038 |
| Length of hospital stay | 1.034*** | 1.029 to 1.039 | 1.03 | 1.024 to 1.035 | 1.052*** | 1.041 to 1.064 |
***p<0.01, **p<0.05, *p<0.1.
†Following IDI protocols, all sample sizes (including the number of hospitals) have been rounded to the nearest multiple of three.
COPD, chronic obstructive pulmonary disease; IDI, Integrated Data Infrastructure; MI, myocardial infarction; NDVI, Normalised Difference Vegetation Index; NZ, New Zealand; NZDep, New Zealand Deprivation Index.