Descriptive characteristics of the study participants by visual status with multiple imputation (n=19 452)
| Variables | Visual status | ||||
| Excellent | Very good | Good | Fair/poor | Total | |
| (n=1770) | (n=5669) | (n=10 475) | (n=1539) | (n=19 452) | |
| Frequency of laughing, n (%) | |||||
| Almost every day | 990 (55.9) | 2649 (46.7) | 4079 (38.9) | 480 (31.2) | 8197 (42.1) |
| <1–5 days/week | 560 (31.6) | 2215 (39.1) | 4294 (41.0) | 597 (38.8) | 7666 (39.4) |
| 1–3 days/month | 148 (8.3) | 589 (10.4) | 1424 (13.6) | 254 (16.5) | 2415 (12.4) |
| <1 day/month | 73 (4.1) | 215 (3.8) | 678 (6.5) | 208 (13.5) | 1174 (6.0) |
| Number of opportunities to laugh, n (%) | |||||
| ≥4 Opportunities | 562 (31.7) | 1639 (28.9) | 2542 (24.3) | 278 (18.0) | 5020 (25.8) |
| 2–3 Opportunities | 895 (50.6) | 3106 (54.8) | 5736 (54.8) | 738 (48.0) | 10 475 (53.9) |
| <1 Opportunity | 314 (17.7) | 924 (16.3) | 2197 (21.0) | 523 (34.0) | 3957 (20.3) |
| Age, years, n (%) | |||||
| 65–69 | 674 (38.1) | 1854 (32.7) | 3232 (30.8) | 362 (23.5) | 6122 (31.5) |
| 70–74 | 468 (26.5) | 1622 (28.6) | 2892 (27.6) | 354 (23.0) | 5336 (27.4) |
| 75–79 | 342 (19.3) | 1289 (22.7) | 2386 (22.8) | 378 (24.6) | 4395 (22.6) |
| 80–84 | 198 (11.2) | 638 (11.2) | 1389 (13.3) | 290 (18.8) | 2515 (12.9) |
| ≥85 | 88 (5.0) | 266 (4.7) | 576 (5.5) | 154 (10.0) | 1084 (5.6) |
| Sex, n (%) | |||||
| Male | 790 (44.6) | 2665 (47.0) | 4814 (46.0) | 706 (45.9) | 8975 (46.1) |
| Female | 980 (55.4) | 3004 (53.0) | 5657 (54.0) | 833 (44.1) | 10 477 (53.9) |
| Marital status, n (%) | |||||
| Married | 1343 (75.9) | 4293 (75.7) | 7623 (72.8) | 1005 (65.3) | 14 264 (73.3) |
| Widowed | 291 (16.5) | 1011 (17.8) | 2062 (19.7) | 374 (24.3) | 3739 (19.2) |
| Separated | 80 (4.5) | 205 (3.6) | 467 (4.5) | 98 (6.3) | 850 (4.4) |
| Unmarried | 57 (3.2) | 159 (2.8) | 322 (3.1) | 61 (4.0) | 600 (3.1) |
| Years of education, n (%) | |||||
| <9 | 481 (27.2) | 1554 (27.4) | 3422 (32.7) | 687 (44.6) | 6144 (31.6) |
| 10–12 | 749 (42.3) | 2412 (42.5) | 4491 (42.9) | 551 (35.8) | 8202 (42.2) |
| ≥13 | 541 (30.5) | 1703 (30.0) | 2562 (24.5) | 301 (19.6) | 5107 (26.3) |
| Equivalized income, million Yen, n (%) | |||||
| Low | 757 (42.8) | 2520 (44.5) | 5449 (52.0) | 963 (62.6) | 9690 (49.8) |
| Middle | 739 (41.8) | 2436 (43.0) | 4000 (38.2) | 463 (30.1) | 7638 (39.3) |
| High | 274 (15.5) | 713 (12.6) | 1025 (9.8) | 112 (7.3) | 2124 (10.9) |
| Depression, n (%) | |||||
| Depression | 194 (11.0) | 762 (13.4) | 2546 (24.3) | 655 (42.6) | 4157 (21.4) |
| No depression | 1576 (89.1) | 4907 (86.5) | 7929 (75.7) | 883 (57.4) | 15 295 (78.6) |
| Frequency of meeting friends, n (%) | |||||
| ≥2–3 days/week | 771 (43.6) | 2290 (40.4) | 3645 (34.8) | 489 (31.8) | 7194 (37.0) |
| <2–3 days/week | 999 (56.5) | 3379 (59.6) | 6830 (65.2) | 1050 (68.2) | 12 258 (63.0) |
| Total participation score, n (%) | |||||
| No participation | 736 (41.6) | 2403 (42.4) | 4910 (46.9) | 868 (56.4) | 8918 (45.8) |
| 1 Organisation | 309 (17.5) | 958 (16.9) | 1837 (17.5) | 237 (15.4) | 3341 (17.2) |
| 2 Organisations | 308 (17.4) | 1003 (17.7) | 1675 (16.0) | 199 (12.9) | 3185 (16.4) |
| ≥3 Organisations | 417 (23.6) | 1304 (23.0) | 2053 (19.6) | 235 (15.2) | 4008 (20.6) |
| History of systemic comorbidities, n(%) | |||||
| No history | 819 (46.2) | 2487 (43.9) | 4089 (39.0) | 414 (26.9) | 7808 (40.1) |
| One disease | 750 (42.4) | 2430 (42.9) | 4527 (43.2) | 663 (43.1) | 8371 (43.0) |
| Two diseases | 190 (10.7) | 658 (11.6) | 1593 (15.2) | 368 (23.9) | 2809 (14.4) |
| Three or more diseases | 12 (0.7) | 93 (1.6) | 265 (2.5) | 94 (6.1) | 464 (2.4) |