Table 2 Baseline characteristics of the subcohort, by area residence urban/rural

Age—mean ± SD (years)

49.48 ± 9.32

49.04 ± 9.20

51.25 ± 9.58

 35–44 years

2772 (34.7%)

2326 (36.4%)

446 (28.1%)

 45–54 years

2708 (33.9%)

2185 (34.2%)

523 (32.9%)

 55–64 years

1914 (24%)

1460 (22.9%)

454 (28.6%)

 ≥ 65

584 (7.3%)

416 (6.5%)

167 (10.5%)

Sex

 Men

3824 (47.9%)

3198 (50.1%)

625 (39.3%)

 Female

4154 (52.1%)

3189 (49.9%)

965 (60.7%)

Ethnicity

 Fars

3874 (48.6%)

3721 (58.3%)

152 (9.6%)

 Lur Bakhtiari

3122 (39.1%)

1775 (27.8%)

1347 (84.7%)

 Turk Qashqai

649 (8.1%)

619 (9.7%)

30 (1.9%)

 Other

333 (4.2%)

272 (4.3%)

61 (3.8%)

Number of family members—mean ± SD

4.00 ± 1.29

3.89 ± 1.14

4.45 ± 1.69

Number of family members—n (%)

 1

84 (1.1%)

59 (0.9%)

25 (1.6%)

 2

782 (10%)

617 (9.9%)

165 (10.5%)

 3

1745 (22.3%)

1477 (23.6%)

267 (17%)

 4 or more

5205 (66.6%)

4096 (65.5%)

1109 (70.8%)

Marital status

 Single

137 (1.7%)

112 (1.8%)

25 (1.6%)

 Married

7520 (94.3%)

6074 (95.1%)

1445 (90.9%)

 Widow and divorced

321 (4%)

201 (3.1%)

120 (7.5%)

Education (N years)—mean ± SD

8.95 ± 6.01

10.16 ± 5.69

4.13 ± 2.08

 Illiterate

1142 (14.3%)

593 (9.3%)

549 (34.5%)

 ≤ 5 years

1689 (21.2%)

1120 (17.5%)

569 (35.8%)

 6–8 years

891 (11.2%)

702 (11%)

189 (11.9%)

 9–12 years

2059 (25.8%)

1855 (29%)

203 (12.8%)

 > 12 years

2197 (27.5%)

2117 (33.1%)

80 (5%)

Occupational status

 Employee

1450 (18.2)

1389 (21.7%)

60 (3.8%)

 Farmer/rancher/herder

293 (3.7)

122 (1.9%)

171 (10.8%)

 Carpet weaver/tailor/weaver

311 (3.9)

239 (3.7%)

72 (4.5%)

 Heavy car driver/mechanic and oil change worker

507 (6.4%)

448 (7%)

59 (3.7%)

 Building contractor/worker and builder

470 (5.9%)

311 (4.9%)

159 (10%)

 Housewife/unemployed/retired

4120 (51.6%)

3142 (49.2%)

978 (61.5%)

 Others

827 (10.4%)

736 (11.5%)

91 (5.7%)