PAR {pARccs} | R Documentation |
PAR
estimates the partial attributable risks (PAR) for multiple exposure factors.
The underlying data have to arise from a case-control-study.
PAR(D, E, C = NULL, model)
D |
a vector which holds the case-control state ("1" = case, "0"=control) |
E |
a matrix of the exposure factor/s (all of them have to be dichotomous!) |
C |
a matrix of the confounder/s (all of them have to be categorical!) |
model |
a model formula or an object of class "glm ". |
For the estimation of the PAR the partitioning technique through the interstep of the sequential attributable risks by Eide and Gefeller (1995) is used.
It is assumed that all exposure factors are equally ranking and that there are no equally or hierarchically structured classes of exposure factors.
The needed (adjusted) attributable risks are estimated within the function with access to
the function AdjAR
(look there for further information).
PAR
returns a named matrix which contains the partial attributable risk for
every given exposure factor.
Also if there are only a single exposure factor/confounder you have to enter a matrix, so this will be a matrix with only one column.
It is also important that the given variables in D
, E
and C
are not defined
as factors.
The names of the variables (outcome, exposure factors, confounders) in the argument model
have to be identically to the (column-)names of the entered data.
Furthermore all given exposure factors and confounders have to be part of the argument model
.
Validity of the estimation can only be taken for granted for data with simple random sampling, stratified random sampling or frequency-matching of controls.
To simplify the computation a compressed definition for the PAR is used (see Wille and Gefeller (1996) for detailed information).
Christiane Raemsch
Eide, G.; Gefeller, O. (1995) Sequential and average attributable fractions as aids in the selection of preventive strategies Journal of Clinical Epidemiology 48, 645-55
Wille, L.; Gefeller, O. (1996) Partitioning the disease risk among several exposure factors: a computational solution to an epidemiological problem Advances in Statistical Software 5, 249-56
Land, M.; Vogel, C.; Gefeller, O. (2001) Partitioning methods for multifactorial risk attribution Statistical Methods in Medical Research 10, 217-30
#### partial attributable risks of exposure1 ##### #### and exposure2 if there are no confounders ##### set.seed(2007) dicho <- c(0,1) cc_state <- sample(dicho, 100, replace=TRUE) exposure1 <- sample(dicho, 100, replace=TRUE, prob=c(0.7, 0.3)) exposure2 <- sample(dicho, 100, replace=TRUE, prob=c(0.4, 0.6)) relation <- as.formula(cc_state~exposure1+exposure2) data_exp <- cbind(exposure1, exposure2) PAR_exposures <- PAR(D=cc_state, E=data_exp, model=relation) #### partial attributable risks of exposure1 and ##### #### exposure2 with taking into account confounder1 ##### set.seed(2008) dicho <- c(0,1) cc_state <- sample(dicho, 100, replace=TRUE) exposure1 <- sample(dicho, 100, replace=TRUE, prob=c(0.7, 0.3)) exposure2 <- sample(dicho, 100, replace=TRUE, prob=c(0.4, 0.6)) cat_confounder <- c(0,1,2,3) confounder1 <- sample(cat_confounder, 100, replace=TRUE) data_exp <- cbind(exposure1, exposure2) conf <- matrix(confounder1, ncol=1) colnames(conf) <- c("confounder1") rel_mod <- glm(cc_state~exposure1+exposure2+confounder1, family=binomial) PAR_exposures <- PAR(cc_state, data_exp, conf, rel_mod)