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. 2019 Aug 9;11:70. doi: 10.1186/s13195-019-0527-7

Table 1.

Demographic information of the study participants at baseline (n = 13,462) and comparison between those with and without longitudinal follow-up data

Variable Overall sample (n = 13,462) Participants with follow-up data (n = 10,219) Participants without follow-up data (n = 3243) P valuea
Age, median (IQR) 71 (65–78) 72 (66–78) 70 (64–76) <0.001
Years of education, median (IQR) 16 (14–18) 16 (14–18) 16 (14–18) 0.353
Male sex, n (%) 4629 (34.4) 3541 (34.7) 1088 (33.6) 0.250
Ethnicity, n (%) <0.001
 White 10,633 (79.0) 8209 (80.3) 2424 (74.8)
 African American 1924 (14.3) 1397 (13.7) 527 (16.3)
 Others/unknown 905 (6.7) 613 (6.0) 292 (9.0)
Marital status, n (%) < 0.001
 Married 7988 (59.3) 6095 (59.6) 1893 (58.4)
 Widowed 2566 (19.1) 2047 (20.0) 519 (16.0)
 Divorced/separated 1964 (14.6) 1382 (13.5) 582 (18.0)
 Single 829 (6.2) 611 (6.0) 218 (6.7)
 Other/unknown 115 (0.9) 84 (0.8) 31 (1.0)
Living arrangement, n (%) < 0.001
 Lives alone 4445 (33.0) 3409 (33.4) 1036 (32.0)
 Lives with spouse 7817 (58.1) 5970 (58.4) 1847 (57.0)
 Lives with relative or friend 933 (6.9) 675 (6.6) 258 (8.0)
 Lives with group/other 267 (2.0) 165 (1.6) 102 (3.2)
Type of residence, n (%) < 0.001
 Private residence 12,207 (90.7) 9146 (89.5) 3061 (94.4)
 Retirement community 950 (7.1) 821 (8.0) 129 (4.0)
 Assisted living/nursing home/other 305 (2.3) 252 (2.5) 53 (1.6)
Primary reason of participation, n (%) < 0.001
 To participate in research 11,848 (88.0) 9088 (88.9) 2760 (85.1)
 For clinical evaluation 1240 (9.2) 927 (9.1) 313 (9.7)
 For clinical evaluation and participate in research 359 (2.7) 192 (1.9) 167 (5.2)
 Unknown 15 (0.1) 12 (0.1) 3 (0.1)
Primary source of referral, n (%) < 0.001
 Self/relative/friend 5685 (42.2) 4217 (41.3) 1468 (45.3)
 Healthcare providers 2441 (18.1) 1634 (16.0) 807 (24.9)
 Other 4924 (36.6) 4016 (39.3) 908 (28.0)
 Unknown 412 (3.1) 352 (3.4) 60 (1.9)
Family history of dementia, n (%) 7274 (54.0) 5700 (55.8) 1574 (48.5) < 0.001
Current smoker, n (%) < 0.001
 Yes 664 (4.9) 507 (5.0) 157 (4.8)
 No 12,774 (94.9) 9703 (95.0) 3071 (94.7)
 Missing data 24 (0.2) 9 (0.1) 15 (0.5)
Diabetes mellitus, n (%) 0.008
 Yes 1592 (11.8) 1160 (11.4) 432 (13.3)
 No 11,832 (87.9) 9028 (88.4) 2804 (86.5)
 Missing data 38 (0.3) 31 (0.3) 7 (0.2)
Hypertension, n (%) 0.225
 Yes 6628 (49.2) 5074 (49.7) 1554 (47.9)
 No 6795 (50.5) 5116 (50.1) 1679 (51.8)
 Missing data 39 (0.3) 29 (0.3) 10 (0.3)
Hyperlipidemia, n (%) 0.452
 Yes 6609 (49.1) 5038 (49.3) 1571 (48.4)
 No 6693 (49.7) 5065 (49.6) 1628 (50.2)
 Missing data 160 (1.2) 116 (1.1) 44 (1.4)
MMSE score, median (IQR) 29 (28–30) 29 (28–30) 29 (28–30) 0.607
GDS score, median (IQR) 1 (0–2) 1 (0–2) 1 (0–2) < 0.001
Presence of depression (GDS ≥ 4), n (%) 1471 (10.9) 993 (9.7) 478 (14.7) < 0.001
Presence of SCD, n (%) 3582 (26.6) 2605 (25.5) 977 (30.1) < 0.001

IQR interquartile range, MMSE Mini-Mental State Examination, GDS geriatric depression scale, SCD subjective cognitive decline

aTest of difference between participants with and without longitudinal follow-up data: chi-square test for categorical variables and Mann-Whitney U test for continuous variables. Italicized P values are ≤ 0.05