Frailty Index versus Age Plot. Frailty index versus age plot of baseline (light and dark red) and 18 month follow up (light and dark blue). Shown here are the average (dark blue/red) and the observed 99th percentile (light blue/red) lines. The slope of the best fit curves shows no accumulation of deficits in the most impaired (99th) of the sample. By contrast the follow up average curve has 2.6% deficit accumulation per year. The baseline average curve has a 2.0% deficit accumulation per year; the 99th percentile slope also shows no accumulation of deficits with age.