Table 1. Baseline Characteristics of the Study Participants.
| Characteristic | Participants, No. (%) | |
|---|---|---|
| Exposed group: spouses of patients with cancer (n = 546 321) | Unexposed group: spouses of individuals without cancer (n = 2 731 574)a | |
| Sex | ||
| Male | 251 462 (46.0) | 1 257 287 (46.0) |
| Female | 294 859 (54.0) | 1 474 287 (54.0) |
| Age at cohort entry, y | ||
| Median (IQR) | 60 (51-68) | 60 (51-68) |
| 18-39 | 40 536 (7.4) | 202 815 (7.4) |
| 40-59 | 219 315 (40.1) | 1 096 933 (40.2) |
| 60-79 | 265 352 (48.6) | 1 326 215 (48.6) |
| 80-104 | 21 118 (3.9) | 105 611 (3.9) |
| Calendar year of cohort entry | ||
| 1973-1989 | 43 048 (7.9) | 215 237 (6.4) |
| 1990-1999 | 126 383 (23.1) | 631 914 (23.1) |
| 2000-2009 | 213 427 (39.1) | 1 067 113 (39.1) |
| 2010-2016 | 163 463 (29.9) | 817 310 (29.9) |
| Country of residence | ||
| Denmark | 384 553 (70.4) | 1 922 757 (70.4) |
| Sweden | 161 768 (29.6) | 808 817 (29.6) |
| Household incomeb | ||
| Below the lowest tertile | 219 660 (40.2) | 1 177 648 (43.1) |
| Between the lowest and middle tertile | 110 204 (20.2) | 528 201 (19.3) |
| Above the highest tertile | 214 779 (39.3) | 1 014 446 (37.1) |
| Unknown | 1678 (0.3) | 11 279 (0.4) |
| History of cancer | ||
| Yes | 47 664 (8.7) | 208 333 (7.6) |
| No | 498 657 (91.3) | 2 523 241 (92.4) |
| Years of education | ||
| 0-9 | 172 481 (31.6) | 877 236 (32.1) |
| 10-14 | 244 312 (44.7) | 1 203 844 (44.1) |
| ≥15 | 89 775 (16.4) | 440 254 (16.1) |
| Unknown | 39 753 (7.3) | 210 240 (7.7) |
a
Individually matched by sex, year of birth, and country of residence. Date of cohort entry was the date of cancer diagnosis for the exposed spouses.
b
Household income was classified into 3 groups according to the tertile distribution of each 10-year intervals in each country.