Characteristics of recruitment networks and research registry pre-notification groups
| Recruitment networks | Research registry pre-notification cohorts§ | ||||
| Social media | Research registry | Control | |||
| Subjects n | 292 | 283 | 120 | 100 | 63 |
| Mean±sd age years | 47.05±8.66 | 63.50±10.44*** | 63.03±10.42 | 64.02±10.14 | 63.56±3.14 |
| Mean±sd rural identity# | 2.77±0.97 | 3.27±1.40*** | 3.47±1.35 | 3.11±1.43 | 3.14±1.40 |
| Mean±sd rural residence# | 2.63±1.07 | 3.36±1.39*** | 3.49±1.33 | 3.20±1.45 | 3.34±1.41 |
| Mean±sd respiratory symptoms¶ | 3.16±0.77*** | 2.44±0.99 | 2.44±1.02 | 2.46±0.98 | 2.43±1.01 |
| Gender | |||||
| Male | 178 (61) | 120 (42.4) | 56 (46.7) | 41 (41) | 23 (36.5) |
| Female | 96 (32.9) | 160 (56.5)*** | 64 (53.3) | 59 (59) | 37 (58.7) |
| Prefer to not answer | 18 (6.2) | 3 (1.1) | 0 (0) | 0 (0) | 3 (4.8) |
| Race | |||||
| White | 219 (75) | 255 (90.1) | 109 (90.8) | 89 (89) | 57 (90.5) |
| Black/African American | 45 (15.4)*** | 9 (3.2) | 4 (3.3) | 3 (3) | 2 (3.2) |
| Asian American | 6 (2.1) | 6 (2.1) | 2 (1.7) | 4 (4) | 0 (0) |
| Native American | 10 (3.4) | 3 (1.1) | 2 (1.7) | 1 (1) | 0 (0) |
| Other | 10 (3.4) | 9 (3.2) | 3 (2.5) | 3 (3) | 3 (4.8) |
| Prefer to not answer | 2 (0.7) | 1 (0.4) | 0 (0) | 0 (0) | 1 (1.6) |
| Ethnicity | |||||
| Hispanic | 100 (34.2)*** | 8 (2.8) | 2 (1.7) | 6 (6)*** | 0 (0) |
| Non-Hispanic | 191 (65.4) | 242 (85.5) | 118 (98.3) | 74 (74) | 50 (79.4) |
| Prefer to not answer | 1 (0.3) | 33 (11.7) | 0 (0) | 20 (20) | 13 (20.6) |
| Education | |||||
| Less than high school | 25 (8.5) | 12 (4.3) | 2 (1.6) | 8 (8) | 2 (3.2) |
| High school or equivalent | 30 (10.3) | 36 (12.7) | 16 (13.3) | 9 (9) | 11 (17.5) |
| College experience | 235 (80.5) | 233 (82.3) | 101 (84.1) | 83 (83) | 49 (78.1) |
| Prefer to not answer | 2 (0.7) | 2 (0.7) | 1 (0.8) | 0 (0) | 1 (1.6) |
| Income USD | |||||
| <24 999 | 10 (3.4) | 60 (21.2)*** | 20 (16.7) | 24 (24) | 16 (25.4) |
| 25 000–34 999 | 30 (10.3) | 30 (10.6) | 13 (10.8) | 12 (12) | 5 (7.9) |
| 35 000–49 999 | 95 (32.5) | 29 (10.2) | 14 (11.7) | 9 (9) | 6 (9.5) |
| 50 000–74 999 | 91 (31.2) | 56 (19.8) | 26 (21.7) | 20 (20) | 10 (15.9) |
| ≥75 000 | 66 (22.6) | 90 (31.8) | 35 (29.2) | 33 (33) | 22 (34.9) |
| Prefer to not answer | 0 (0) | 18 (6.4) | 12 (10) | 2 (2) | 4 (6.3) |
| Employment status | |||||
| Full-time | 221 (75.7) | 55 (19.4) | 24 (20) | 18 (18) | 13 (20.6) |
| Part-time | 29 (9.9) | 12 (4.2) | 6 (5) | 3 (3) | 3 (4.8) |
| Unemployed | 7 (2.4) | 8 (2.8) | 5 (4.2) | 1 (1) | 2 (3.2) |
| Retired | 20 (6.8) | 126 (44.5)*** | 59 (49.2) | 39 (39) | 28 (44.4) |
| Disabled | 9 (3.1) | 70 (24.7) | 23 (19.2) | 34 (34) | 13 (20.6) |
| Other | 3 (1.0) | 8 (2.8) | 3 (2.5) | 3 (3) | 2 (3.2) |
| Prefer to not answer | 3 (1.0) | 4 (1.4) | 0 (0) | 2 (2) | 2 (3.2) |
| Marital status | |||||
| Married | 234 (80.1)*** | 161 (57.3) | 75 (62.5) | 56 (56) | 30 (47.6) |
| Divorced | 24 (8.2) | 64 (22.8) | 27 (22.5) | 21 (21) | 16 (25.4) |
| Widowed | 11 (3.8) | 32 (11.4) | 11 (9.2) | 13 (13) | 8 (12.7) |
| Separated | 11 (3.8) | 6 (2.1) | 1 (0.8) | 2 (2) | 3 (4.8) |
| Single, never married | 11 (3.8) | 18 (6.4) | 5 (4.2) | 8 (8) | 5 (7.9) |
| Prefer to not answer | 1 (0.3) | 2 (0.7) | 1 (0.8) | 0 (0) | 1 (1.6) |
| Health insurance status | |||||
| Insured | 246 (84.2) | 266 (94.7)** | 115 (96.7) | 91 (91) | 59 (93.7) |
| Uninsured | 32 (11) | 13 (4.6) | 4 (3.3) | 6 (6) | 3 (4.8) |
| Not sure | 10 (3.4) | 2 (0.7) | 0 (0) | 2 (2) | 0 (0) |
| Prefer to not answer | 4 (1.4) | 2 (0.7) | 0 (0) | 1 (1) | 1 (1.6) |
| Chronic disease+ | |||||
| COPD | 264 (90.4)*** | 143 (50.5) | 59 (49.2) | 57 (57) | 27 (57.1) |
| Heart disease | 22 (7.5) | 70 (24.7)*** | 23 (19.2) | 30 (30) | 17 (27) |
| Cancer | 15 (5.1) | 49 (17.3)*** | 17 (14.2) | 22 (22) | 10 (15.9) |
| Type 2 diabetes | 29 (9.9) | 54 (19.1)** | 22 (18.3) | 22 (22) | 10 (15.9) |
| Arthritis | 14 (4.8) | 104 (40.6)*** | 33 (35.5) | 46 (46) | 25 (39.7) |
| Chronic pain | 20 (6.8) | 101 (35.7)*** | 41 (34.2) | 37 (37) | 23 (36.5) |
| Other | 8 (2.7) | 27 (9.5)** | 13 (10.8) | 7 (7) | 7 (11.1) |
Data are presented as n (%), unless otherwise stated. COPD: chronic obstructive pulmonary disease. #: rural identity and region were measured on a five-point scale, 1=urban (city) and 5=rural (small town); ¶: respiratory symptoms were measured on a five-point scale, 1=low and 5=high; +: chronic disease percentages exceed 100%, given that participants could report multiple chronic conditions; §: mailer pre-notification 17.14% response rate, e-mail pre-notification 14.29% response rate, control 9% response rate. **: p<0.01; ***: p<0.001.