Participants’ characteristics at baseline
| Characteristic | Baseline | |||
| All participants (n=1634) | Complete follow-up (n=1211) | Incomplete follow-up (n=423) | P value* | |
| Sex, no. (%) | ||||
| Male | 798 (48.8) | 592 (48.9) | 206 (48.7) | 0.948 |
| Female | 836 (51.2) | 619 (51.1) | 217 (51.3) | |
| Data missing | 0 | 0 | 0 | |
| Age (years), no. (%) | ||||
| 50–59 | 520 (31.6) | 366 (30.2) | 154 (36.4) | <0.001 |
| 60–69 | 579 (35.4) | 395 (32.5) | 184 (43.7) | |
| 70–79 | 423 (25.9) | 365 (30.2) | 58 (13.7) | |
| ≧80 | 112 (6.7) | 85 (6.9) | 27 (6.3) | |
| Data missing | 0 | 0 | 0 | |
| Education level, no. (%) | ||||
| Less than high school | 73 (4.8) | 57 (5.2) | 16 (4.0) | 0.817 |
| High school | 545 (36.2) | 399 (36.1) | 146 (36.4) | |
| Junior college | 286 (19.0) | 207 (18.7) | 79 (19.7) | |
| More than or equal to college | 593 (39.4) | 437 (39.6) | 156 (38.9) | |
| Data missing | 137 | 111 | 26 | |
| Annual household income (million JPY), no. (%) | ||||
| <3.00 (≒US$30 000) | 430 (27.0) | 321 (27.2) | 109 (26.3) | 0.452 |
| 3.00–4.99 | 482 (30.3) | 361 (30.6) | 121 (29.2) | |
| 5.00–6.99 | 267 (16.8) | 199 (16.9) | 68 (16.4) | |
| 7.00–9.99 | 224 (14.1) | 153 (13.0) | 71 (17.1) | |
| ≧10.00 | 189 (11.9) | 144 (11.9) | 45 (10.9) | |
| Data missing | 42 | 33 | 9 | |
| Marital status, no. (%) | ||||
| Married | 1237 (76.2) | 927 (77.0) | 310 (74.0) | 0.692 |
| Widowed | 112 (6.9) | 79 (6.6) | 33 (7.9) | |
| Annulled, divorced, separated | 113 (6.9) | 79 (6.5) | 34 (8.1) | |
| Never married | 161 (9.9) | 119 (9.9) | 42 (10.0) | |
| Data missing | 11 | 7 | 4 | |
| Number of chronic health conditions, no. (%) | ||||
| 0 | 408 (25.0) | 291 (24.0) | 117 (27.7) | 0.307 |
| 1 | 457 (28.0) | 329 (27.2) | 128 (30.3) | |
| 2 | 315 (19.3) | 248 (20.5) | 67 (15.8) | |
| 3 | 220 (13.5) | 161 (13.3) | 59 (13.9) | |
| 4 | 110 (6.7) | 82 (6.8) | 28 (6.6) | |
| ≧5 | 124 (7.6) | 100 (8.3) | 24 (5.7) | |
| SF-36 | ||||
| PCS Score, mean (SD) | 47.6 (11.8) | 47.5 (11.4) | 47.9 (12.8) | 0.595 |
| MCS Score, mean (SD) | 49.4 (10.4) | 49.7 (10.2) | 48.4 (11.0) | 0.032 |
| RCS Score, mean (SD) | 50.3 (11.0) | 50.5 (10.9) | 49.8 (11.2) | 0.294 |
*P value by t-test for continuous data and χ2 test for categorical data.
MCS, mental component summary; PCS, physical component summary; RCS, role/social component summary; SF-36, 36-Item Short Form Health Survey.