Interval | Age Range (years) | # of Carriers | Not Yet of Agea | Deaths (CJD) | Deaths (non-CJD) |
Q
i
|
S
i
| 1 − Si |
|---|
1 | <30 | 79 | 4 | 0 | 0 | 1.00 | 1.00 | 0.00 |
2 | 31–40 | 75 | 6 | 1 | 0 | 0.99 | 0.99 | 0.01 |
3 | 41–50 | 68 | 10 | 9 | 0 | 0.86 | 0.85 | 0.15 |
4 | 51–60 | 49 | 10 | 16 | 0 | 0.64 | 0.55 | 0.45 |
5 | 61–70 | 23 | 4 | 12 | 0 | 0.43 | 0.23 | 0.77 |
6 | 71–80 | 7 | — | 3 | 2 | 0.50 | 0.11 | 0.89 |
7 | >80 | 2 | — | 1 | 1 | 0.33 | 0.04 | 0.96 |
- Qi is the probability that a CJD gene carrier has not become affected by the end of age interval (i), and the “life table” estimate of Qi is:
\({Q_i} = {{{n_i} - {d_i} - {c_i}{\rm{/}}2} \over {{n_i} - {c_i}{\rm{/}}2}}\)
where ni = # gene carriers alive at the beginning of the ith interval, ci = # of individuals “censored”, or removed from the study during the ith interval,a and di = # individuals affected with CJD during the ith interval. The cumulative probability (Si) of surviving from the beginning of the study to the end of the ith interval without developing CJD is calculated by:
\({S_i} = {Q_1} \times {Q_2} \ldots \times {Q_i}\).
- aBecause they have not yet reached the “end of interval” age, or they have died from another cause.
