Table 3.
Cox regression model on the effect of age group at RRT start on mortality, adjusting age group by other variables
| Variable | Hazard ratio | 95% CI | P-value |
|---|---|---|---|
| Age group (years) | |||
| 11–<16 | 1.00 | ||
| 16–<21 | 1.87 | 0.95–3.67 | 0.07 |
| 21–<26 | 2.12 | 1.11–4.05 | 0.02 |
| 26–30 | 2.04 | 1.07–3.87 | 0.03 |
| Sex | |||
| Male | 1.00 | ||
| Female | 1.13 | 0.88–1.46 | 0.3 |
| Ethnicity | |||
| White | 1.00 | ||
| Asian | 0.59 | 0.36–0.98 | 0.04 |
| Black | 0.71 | 0.43–1.15 | 0.2 |
| Other | 0.64 | 0.30–1.38 | 0.3 |
| Year of start | |||
| 1999-2002 | 1.35 | 1.00–1.83 | 0.05 |
| 2003-2005 | 0.97 | 0.71–1.33 | 0.9 |
| 2006-2008 | 1.00 | ||
| Modality | |||
| Transplant | 1.00 | ||
| Dialysis, transplant listed | 4.20 | 2.61–6.75 | <0.0001 |
| Dialysis, not transplant listed | 16.6 | 10.8–25.4 | <0.0001 |
| Primary renal diagnosis | |||
| Glomerular Diseasea | 1.00 | ||
| Familial/hereditary nephropathies | |||
| Other familial/hereditary nephropathies | 0.59 | 0.21–1.66 | 0.3 |
| Polycystic kidney disease | 1.07 | 0.33–3.44 | 0.9 |
| Miscellaneous renal disorders | 1.88 | 1.28–2.76 | 0.001 |
| Systemic diseases affecting the kidney | |||
| Diabetesb | 4.03 | 2.71–6.01 | <0.0001 |
| Other systemic diseasesc | 1.93 | 1.08–3.48 | 0.03 |
| Tubulointerstitial disease | |||
| Obstructive | 1.37 | 0.78–2.40 | 0.3 |
| Renal dysplasia ± reflux | 0.43 | 0.20–0.97 | 0.04 |
| Other tubulointerstitial diseased | 6.49 | 4.07–10.4 | <0.0001 |
Data based on 3243 patients and 248 events and excludes those with a missing ethnicity or PRD.
Glomerular disease was chosen as a comparator, as it was the most frequent diagnosis.
There was a significant non-proportionality over time between those with and without diabetes, with the effect seen only after 230 days and no effect on other HRs when using a piecewise Cox regression analysis; this model presents the overall HR for the entire follow-up period.
PRD codes in the ‘other systemic diseases’ group include amyloid, haemolytic uraemic syndrome, renovascular diseases and hypertension. Of those with amyloid (n = 15), 33.3% died, while the proportion of death from other conditions was 6.6, 8.6 and 6.5%, respectively.
PRD codes in the ‘other tubulointerstitial disease’ group include drug-induced tubulopathies and interstitial nephritis; of those with drug-induced tubulopathies (n = 65), 32.3% died and of those with interstitial nephritis (n = 45), 15.6% died.