Calculate age standardised rates by sub-group with confidence intervals in R

Question

I have a dataframe which looks like this:

df <- data.frame (
  time = rep(c("2010", "2011", "2012", "2013", "2014"),4),
  age = rep(c("40-44", "45-49", "50-54", "55-59", "60-64"),4),
 weight = rep(c(0.38, 0.23, 0.19, 0.12, 0.08),4),
 ethnic = rep(c(rep("M",5),rep("NM",5)),2),
 gender = c(rep("M",10), rep("F",10)),
 pop = round((runif(10, min = 10000, max = 99999)), digits = 0),
 count = round((runif(10, min = 100, max = 999)), digits = 0)
)
df$rate = df$count / df$pop

I want to calculate the direct age standardised incidence rates, where incidence rate = count/pop), and confidence intervals for these; for each subgrouping. So I would have a standardised rate for each combination of time, gender, ethnicity, age. Is there a way to do this in R?

I have tried using the function ageadjust.direct from the R package {epitools}, as so:

age_adjust_test <- ageadjust.direct(count = df$count, pop = df$pop, 
                                rate = df$rate, stdpop = df$weight)

The output from this is an overall adjusted rate, confidence intervals, and crude rate. Is there a way to get this output by each sub-group?

Answer 1

We can do a group by summarise into a list and then unnest the list components into separate columns

library(tidyverse)
df %>% 
   group_by(time,age, ethnic, gender) %>% 
   summarise(age_adjust = list(ageadjust.direct(count = count,
            pop = pop, rate = rate, stdpop = weight))) %>%
   mutate(age_adjust = map(age_adjust, as.data.frame.list))  %>% 
   unnest
# A tibble: 20 x 8
# Groups:   time, age, ethnic [10]
#   time  age   ethnic gender crude.rate adj.rate     lci     uci
#   <fct> <fct> <fct>  <fct>       <dbl>    <dbl>   <dbl>   <dbl>
# 1 2010  40-44 M      F         0.00763  0.00763 0.00709 0.00820
# 2 2010  40-44 M      M         0.00763  0.00763 0.00709 0.00820
# 3 2010  40-44 NM     F         0.0281   0.0281  0.0257  0.0306 
# 4 2010  40-44 NM     M         0.0281   0.0281  0.0257  0.0306 
# 5 2011  45-49 M      F         0.0145   0.0145  0.0136  0.0155 
# 6 2011  45-49 M      M         0.0145   0.0145  0.0136  0.0155 
# 7 2011  45-49 NM     F         0.0425   0.0425  0.0399  0.0453 
# 8 2011  45-49 NM     M         0.0425   0.0425  0.0399  0.0453 
# 9 2012  50-54 M      F         0.0116   0.0116  0.0109  0.0124 
#10 2012  50-54 M      M         0.0116   0.0116  0.0109  0.0124 
#11 2012  50-54 NM     F         0.00708  0.00708 0.00607 0.00821
#12 2012  50-54 NM     M         0.00708  0.00708 0.00607 0.00821
#13 2013  55-59 M      F         0.0251   0.0251  0.0232  0.0271 
#14 2013  55-59 M      M         0.0251   0.0251  0.0232  0.0271 
#15 2013  55-59 NM     F         0.00733  0.00733 0.00678 0.00792
#16 2013  55-59 NM     M         0.00733  0.00733 0.00678 0.00792
#17 2014  60-64 M      F         0.0101   0.0101  0.00944 0.0109 
#18 2014  60-64 M      M         0.0101   0.0101  0.00944 0.0109 
#19 2014  60-64 NM     F         0.00916  0.00916 0.00852 0.00984
#20 2014  60-64 NM     M         0.00916  0.00916 0.00852 0.00984