Table 4.

Median times (ranges) to complication by access type and individual frailty category

VariableTime to Noninfectious Events (Range) (mo)Time to Infectious Events (Range) (mo)
Median (Range)25th Percentile Median 25th Percentile
Fistula (n=4733)8.7 (4.7–23.6)1.51 (0.82–4.1)586.0 (184.1–7047.9)110 (35–1329)
Graft (n=2756)3.8 (2.5–12.6)0.67 (0.44–2.2)136.9 (90.4–3459.9)26 (17–652)
Catheter (n=4207)1.8 (1.2–5.9)0.31 (0.21–1.03)82.4 (54.4–2083.5)16 (10–393)
  • Median times are based on predictions from model 3 (Table 3; frailty models). A median time to complication was calculated for each patient on the basis of his or her covariate values. The median values and ranges reported above are the median values and ranges of those median times; thus, the range reflects covariate variability. Frailty models are used in situations when some individuals are more or less prone to experience the event of interest due to some shared (but unmeasured) characteristics. We used frailty models to study repeated outcomes occurring in the same individuals over time, and individuals are more or less prone to fail. Frailty models are survival models that take into account the correlation in the data (risks are more similar within patients than between patients) using random effects. The above predictions are calculated for an average frailty of 1.26