Table 1. LINKAGE Trial Participant Characteristics by Study Group.
| Characteristic | Participants, No. (%) | P value | |
|---|---|---|---|
| LINKAGE (n = 252) | Usual care (n = 251) | ||
| At study enrollment | |||
| Sex | |||
| Male | 175 (69.4) | 171 (68.1) | .77 |
| Female | 77 (30.6) | 80 (31.9) | |
| Age, mean (SD), y | 41.4 (11.6) | 43.5 (12.0) | .07 |
| Race and ethnicity | |||
| African American | 17 (6.7) | 20 (8.0) | .96 |
| Asian | 16 (6.3) | 18 (7.2) | |
| Hispanic | 49 (19.4) | 52 (20.7) | |
| American Indian or Alaska Native | 6 (2.4) | 4 (1.6) | |
| White | 156 (61.9) | 150 (59.8) | |
| Othera | 8 (3.2) | 7 (2.8) | |
| Education | |||
| ≤High school graduate or equivalent | 96 (38.1) | 107 (42.6) | .54 |
| Associate in arts, associate in science, or technical school | 49 (19.4) | 52 (20.7) | |
| College or higher | 107 (42.5) | 92 (36.7) | |
| Annual household income <$50 000 | 112 (44.4) | 113 (45.0) | .93 |
| Substance dependence | |||
| Alcohol | 170 (67.5) | 159 (63.3) | .35 |
| Drug | 124 (49.2) | 108 (43.0) | .18 |
| Opioid | 44 (17.5) | 37 (14.7) | .47 |
| Cocaine | 46 (18.3) | 33 (13.1) | .14 |
| Marijuana | 31 (12.3) | 30 (12.0) | >.99 |
| Amphetamine | 27 (10.7) | 32 (12.7) | .49 |
| Sedative | 18 (7.1) | 13 (5.2) | .46 |
| Charlson Comorbidity Index, mean (SD) | 0.46 (1.3) | 0.59 (1.3) | .07 |
| During 1 y prior to study enrollmentb | |||
| Electronic patient portal use, any | |||
| Logins | 139 (66.8) | 143 (64.1) | .61 |
| Online medication refills | 84 (40.4) | 82 (36.8) | .49 |
| Secure messages sent to health providers | 102 (49.0) | 110 (49.3) | >.99 |
| Health care service visits, any | |||
| Primary care | 171 (82.2) | 196 (87.9) | .11 |
| Emergency department | |||
| Any | 101 (48.6) | 113 (50.7) | .70 |
| Emergent type | 10 (4.8) | 28 (12.6) | .01 |
| Nonemergent type | 32 (15.4) | 42 (18.8) | .37 |
| Substance-related type | 33 (15.9) | 42 (18.8) | .45 |
a
Other race and ethnicity included non-Hispanic participants who indicated having “more than one racial/ethnic background” in the baseline interview.
b
Data for 208 participants in LINKAGE and 223 participants in usual care; data were missing due to insufficient health system enrollment during the 1 year prior to study start, resulting in no health care utilization data.