|  | Baseline | 7-month |  | 20-month |  | ||
---|---|---|---|---|---|---|---|---|
 |  |  | interviewed | no | p | interviewed | no | p |
Sample | Â | 4079 | 2220 | 1859 | Â | 1888 | 2191 | Â |
City, No. (%) | lanzhou | 2961 (72.6) | 1603 (72.2) | 1358 (73.1) | .55 | 1572 (71.7) | 1389 (73.6) | .19 |
 | baiyin | 1118 (27.4) | 617 (27.8) | 501 (26.9) |  | 619 (28.3) | 499 (26.4) |  |
sex, No. (%) | Male | 1919 (47.0) | 1076 (48.5) | 843 (45.3) | .05 | 1027 (54.4) | 892 (40.7) | <.001 |
 | Female | 2160 (53.0) | 1144 (51.5) | 1016 (54.7) |  | 861 (45.6) | 1299 (59.3) |  |
age, No. (%) | 16-35 | 777 (19.0) | 326 (14.7) | 451 (24.3) | <.001 | 517 (23.6) | 260 (13.8) | <.001 |
 | 36-45 | 1220 (29.9) | 655 (29.5) | 565 (30.4) |  | 664 (30.3) | 556 (29.4) |  |
 | 46-55 | 1048 (25.7) | 617 (27.8) | 431 (23.2) |  | 525 (24.0) | 523 (27.7) |  |
 | 56-65 | 674 (16.5) | 388 (17.5) | 286 (15.4) |  | 324 (14.8) | 350 (18.5) |  |
 | > = 66 | 360 (8.8) | 234 (10.5) | 126 (6.8) |  | 161 (7.3) | 199 (10.5) |  |
Ethnicity, No. (%) | Han | 3848 (94.3) | 2107 (94.9) | 1741 (93.7) | .08 | 1774 (94.0) | 2074 (94.7) | 0.34 |
 | Minority | 231 (5.7) | 113 (5.1) | 118 (6.3) |  | 114 (6.0) | 117 (5.3) |  |
education, No. (%) | primary or less | 759 (18.6) | 444 (20.0) | 315 (16.9) | .001 | 362 (19.2) | 397 (18.1) | 0.25 |
 | Junior high school | 1482 (36.3) | 825 (37.2) | 657 (35.3) |  | 705 (37.3) | 777 (35.5) |  |
 | High school | 1384 (33.9) | 735 (33.1) | 649 (34.9) |  | 625 (33.1) | 759 (34.6) |  |
 | College or above | 454 (11.1) | 216 (9.7) | 238 (12.8) |  | 196 (10.4) | 258 (11.8) |  |
Dibao, No. (%) | yes | 3283 (80.5) | 821 (37.0) | 559 (30.1) | <.001 | 691 (36.6) | 689 (31.4) | <.001 |
 | no | 537 (13.2) | 1399 (63.0) | 1300 (69.9) |  | 1197 (63.4) | 1502 (68.6) |  |
marriage, No. (%) | Married | 257 (6.3) | 1741 (78.5) | 1542 (83.0) | Â | 1460 (77.4) | 1823 (83.2) | <.001 |
 | Divorced | 1286 (31.5) | 407 (18.3) | 130 (7.0) | .001 | 374 (19.8) | 163 (7.4) |  |
 | Never-married | 1458 (35.7) | 71 (3.2) | 186 (10.0) |  | 53 (2.8) | 204 (9.3) |  |
employment, No. (%) | retired | 1335 (32.7) | 750 (33.8) | 536 (28.8) | <.001 | 645 (29.4) | 641 (34.0) | <0.01 |
 | unemployed | 1380 (33.8) | 789 (35.5) | 669 (36.0) |  | 802 (36.6) | 656 (34.7) |  |
 | employed | 2699 (66.2) | 681 (30.7) | 654 (35.2) |  | 744 (34.0) | 591 (31.3) |  |
health insurance, No. (%) | no | 2445 (59.9) | 1331 (60.0) | 1114 (59.9) | .98 | 1081 (57.3) | 1364 (62.3) | .001 |
 | yes | 1634 (40.1) | 889 (40.0) | 745 (40.1) |  | 807 (42.7) | 827 (37.7) |  |
CES-D Baseline, No. (%) | <16 | 1742 (42.7) | 917 (41.3) | 825 (44.4) | .08 | 974 (44.5) | 768 (40.7) | .06 |
 | 16-20 | 766 (18.8) | 416 (18.7) | 350 (18.8) |  | 405 (18.5) | 361 (19.1) |  |
 | 21-25 | 684 (16.8) | 373 (16.8) | 311 (16.7) |  | 364 (16.6) | 320 (16.9) |  |
 | ≥26 | 887 (21.7) | 514 (23.2) | 373 (20.1) |  | 448 (20.4) | 439 (23.3) |  |