Baseline characteristics
| Characteristics | All participants (n=117) | iSMI (n=59) | AC (n=58) |
| Sociodemographic characteristics | |||
| Age (years), M (SD) | 46.9 (8.3) | 46.9 (8.5) | 46.8 (8.2) |
| Gender, female, n (%) | 78 (67) | 42 (72) | 36 (63) |
| Married or cohabiting, n (%) | 105 (90) | 52 (89) | 53 (90) |
| University level education, n (%) | 106 (91) | 55 (94) | 51 (88) |
| Work characteristics | |||
| Working hours per week, M (SD) | 39.1 (2.5) | 38.8 (3.0) | 39.3 (2.0) |
| Hours of overtime per week, M (SD) | 7.1 (4.9) | 7.0 (4.2) | 7.2 (5.5) |
| Years working as a manager, M (SD) | 8.26 (7.6) | 8.41 (7.7) | 8.10 (7.6) |
| Number of subordinates, M (SD) | 20.4 (22.0) | 18.5 (4.8) | 22.4 (27.5) |
| On sick leave (part-time), n | 1 | 0 | 1 |
| Work sectors, n (%) | |||
| Health and social | 39 (33) | 21 (35) | 18 (31) |
| IT and communication | 16 (14) | 7 (12) | 9 (15) |
| Educational | 15 (13) | 9 (15) | 6 (10) |
| Wholesale and economy | 11 (10) | 5 (9) | 6 (11) |
| Manufacturing | 9 (8) | 3 (6) | 6 (10) |
| Public administration | 9 (7) | 5 (8) | 4 (7) |
| Others | 18 (15) | 9 (15) | 9 (16) |
| Disorder and comorbid characteristics, n (%) | |||
| F43.2 Adjustment disorder | 74 (63) | 34 (58) | 40 (69) |
| F43.8 Other reactions to severe stress | 25 (21) | 14 (24) | 11 (19) |
| F43.9 Reaction to severe stress, unspecified | 18 (15) | 11 (19) | 7 (12) |
| F51.0 Non-organic insomnia | 67 (57) | 40 (68) | 27 (47) |
| F41.1 Generalised anxiety disorder | 10 (9) | 2 (4) | 8 (14) |
| F33.x Recurrent depressive disorder | 10 (9) | 3 (5) | 7 (12) |
| F41.0 Panic disorder | 9 (8) | 6 (10) | 3 (5) |
| F32.x Depressive episode/depression | 8 (7) | 6 (10) | 2 (3) |
| F40.1 Social phobia | 4 (3) | 3 (5) | 1 (2) |
| Non-comorbid | 41 (35) | 16 (27) | 25 (43) |
| Previous experience, n (%) | |||
| Previous SMI or psychotherapy | 34 (29) | 20 (34) | 14 (24) |
| First-time help seeker | 83 (71) | 39 (66) | 44 (76) |
AC, attention control group; IT, information technology; M, mean; n, number; SMI, internet-based stress management intervention.