As we learned in part 5, Table 1 describes your analytical population at baseline by your exposure. For those using a continuous variable as an exposure, it’s by quantile (e.g., tertile, quartile) of the exposure. I propose a table known as “Table 2” that describes the outcome of interest by the exposure used in Table 1. You might have seen something along the lines of this in papers before, and we are going to call it “Table 2”. It’s not a universal table in observational epidemiology, so calling it “Table 2” is a bit much. But we’ll call it “Table 2” for our purposes.
Columns
The columns should be identical to that in your Table 1. (I suggest having an “All” column if you don’t have one in your Table 1 though.)
Rows
In Table 1, I suggested having an N and range for continuous variables of your quantiles. I suggest not including those in your Table 2 if they are already in your Table 1, since it’s duplicative. I suppose it might be helpful for error checking to have them in table 2, and confirming that they are identical to your Table 1. But, I suggest not including a row for Ns and ranges in your Table 2 that is included in the manuscript.
In a very simple Table 2, there might be a single row: the outcome in the analytical population. It might look like this:
| All | Tertile 1 | Tertile 2 | Tertile 3 | |
| All |
BUT! There might be a stratification of interest in your table. in the REGARDS study, we often stratify by Black vs. White race or by sex. So, you might also include rows for each subsequent group, like this:
| All | Tertile 1 | Tertile 2 | Tertile 3 | |
| All | ||||
| Black participants | ||||
| White participants |
Finally, for subgroups, you might opt to include a minimally-adjusted regression comparing your strata. in this example, we could use a modified Poisson regression (i.e., Poisson regression with sandwich or robust variance estimators, Zou’s method) to compare risk of the outcome overall an in each tertile. I’d just adjust for age and sex in this example. So:
| All | Tertile 1 | Tertile 2 | Tertile 3 | |
| All | ||||
| Black participants | ||||
| White participants | ||||
| RR, Black vs. White (ref) |
Cell
Here, I suggest presenting # with event/# at risk (percentage with event) in each cell, except in the RR row, which would present RR and the 95% confidence interval. Example (totally made up numbers here and some placeholder ##’s, as FYI):
| All | Tertile 1 | Tertile 2 | Tertile 3 | |
| All | 1200/3000 (40%) | 300/1000 (30%) | 400/1000 (40%) | 500/1000 (50%) |
| Black participants | 500/1000 (50%) | ##/## (##%) | ##/## (##%) | ##/## (##%) |
| White participants | 700/2000 (35%) | ##/## (##%) | ##/## (##%) | ##/## (##%) |
| RR, Black vs. White (ref) | 1.42 (1.30-1.55) | 1.20 (1.15-1.25) | 1.22 (1.18-1.30) | 1.21 (1.19-1.28) |
That’s it! Even if you don’t include this table, it’s super handy to have to describe the outcome in the text.
Time to event analyses
For time to event analyses, this should be modified a bit. Instead, this should focus on events, follow-up (in person-years), and incident rate (e.g., events in 1000 person-years).