Tabulate the dose assignment rule of the traditional 3+3 design used by
oc_3p3 and sim_3p3: for every number of DLTs
among the three or six patients treated at the current dose, the decision
taken during dose escalation and, for mtd_rule = "expand", during the
search for the MTD that follows it.
Usage
decision_table_3p3(mtd_rule = c("previous", "expand"))Arguments
- mtd_rule
Character scalar, either
"previous"or"expand". The definition of the MTD, as inoc_3p3. Defaults to"previous".
Value
An object of class decision_table_3p3, which is a data frame with one
row per state of the current dose and the columns
- stage
"escalation"for dose escalation, or"search"for the search for the MTD, which onlymtd_rule = "expand"has.- n
Number of patients treated at the current dose, 3 or 6.
- n_tox
Number of patients with a DLT, from 0 to
n.- decision
Decision code. During escalation,
"E"escalates to the next higher dose,"S"treats three more patients at the current dose and"STOP"stops escalation, this dose and all higher doses being too toxic. During the search,"S"treats three more patients at the current dose,"MTD"selects it as the MTD and"D"moves the search to the next lower dose.
The definition of the MTD is stored in the attribute mtd_rule. The
object has print and plot methods.
Details
During escalation three patients are treated at the current dose. No DLT escalates, one DLT adds three more patients at the same dose, and two or more stop escalation. With six patients, at most one DLT escalates and two or more stop escalation. Escalating from the highest dose also ends escalation.
With mtd_rule = "previous" the MTD is the dose below the one at which
escalation stopped, or the highest dose when it was escalated from, and no
MTD is selected when escalation stops at the starting dose. With
mtd_rule = "expand" the search starts at the dose below the one at
which escalation stopped, or at the highest dose when it was escalated from.
A dose with three patients receives three more; a dose with at most one DLT
out of six is selected as the MTD, and one with two or more passes the search
to the next lower dose. No MTD is selected when the search moves below the
starting dose.
Every number of DLTs from 0 to n is listed for six patients, although
in a trial the six patients at a dose during escalation always include one
DLT among the first three. The search examines only doses that were
escalated from, so a dose with three patients has no DLT there, and only that
state is listed.
The rules are those of oc_3p3: the tests follow this table
through every possible course of a trial and obtain the operating
characteristics of oc_3p3().
Examples
decision_table_3p3()
#> 3+3 decision table, MTD rule: previous (the dose below the one declared too toxic)
#>
#> Dose escalation
#> Patients DLTs Decision
#> 3 0 Escalate
#> 3 1 Treat 3 more patients at this dose
#> 3 >= 2 Stop escalation
#> 6 <= 1 Escalate
#> 6 >= 2 Stop escalation
#>
#> Stop escalation means that this dose and all higher doses are too
#> toxic. The MTD is the dose below the one at which escalation stopped,
#> and no MTD is selected when escalation stops at the starting dose. When
#> the highest dose is escalated from, it is the MTD.
# The other definition of the MTD adds the search for the MTD
decision_table_3p3(mtd_rule = "expand")
#> 3+3 decision table, MTD rule: expand (the highest dose with at most 1 DLT in 6)
#>
#> Dose escalation
#> Patients DLTs Decision
#> 3 0 Escalate
#> 3 1 Treat 3 more patients at this dose
#> 3 >= 2 Stop escalation
#> 6 <= 1 Escalate
#> 6 >= 2 Stop escalation
#>
#> Search for the MTD
#> Patients DLTs Decision
#> 3 0 Treat 3 more patients at this dose
#> 6 <= 1 Select this dose as the MTD
#> 6 >= 2 Move to the next lower dose
#>
#> Stop escalation means that this dose and all higher doses are too
#> toxic. The search for the MTD starts at the dose below the one at which
#> escalation stopped, or at the highest dose when it is escalated from.
#> No MTD is selected when the search moves below the starting dose.