Table 1.
Algorithm for Predicting Lifetime Risk and Age-Conditional Risk within a Certain Time Interval with Family History Information
| Step | Procedure |
|---|---|
| 1 | Use the competing risk formula to calculate the lifetime RR for the genotypes in each variant (i.e., calculate the lifetime risk for each genotype by using POR, then divide the lifetime risk of each group by that of a baseline group to obtain the lifetime RR).a |
| 2 | Compute the Vg of all variants; Vg is calculated with overall lifetime risk and the allele frequency and lifetime RR of genotypes as inputs. This forms the measurable liability. |
| 3 | Use the PA formula to take into account covariance between total and measurable liability, and obtain the predicted lifetime risk. |
| 4 | Deduce the R for each year from the overall lifetime absolute risk by solving the competing risk equation (Equation 3). |
| 5 | Knowing R, we can estimate the risk by using any start age and specifying any time period. |
The following abbreviations are used: RR, relative risk; POR, prevalence odds ratio; Vg, variance explained; R, the hazard ratio; PA, Pearson-Aitken. Please refer to So and Sham8 for more details concerning the calculation of lifetime RR. Note that both the heritability and measurable liability refers to liability to a lifetime diagnosis of the disease.
a
Assumes the genetic loci to have constant effects on liability and hazard ratios regardless of age.