TABLE 1. Sample Characteristics and Estimated Nonresponse and Attrition Bias.
| Invited to the First Survey (N = 12,603) | Invited to the First and Second surveys (N = 9304) | |||||
|---|---|---|---|---|---|---|
| Respondents at Baselinea (n = 6774) | Nonresponders at Baseline (n = 5829) | Nonresponse Analysis | Respondents at the First and Second surveysb (n = 3779) | Dropouts (n = 1853) | Attrition Analysisc | |
| n (%) | n (%) | OR (95% CI) | n (%) | n (%) | OR (95% CI) | |
| Sex | ||||||
| Male | 2648 (39.1) | 2035 (34.9) | 1 (reference) | 1529 (40.5) | 675 (36.4) | 1 (reference) |
| Female | 4123 (60.9) | 3266 (56.0) | 0.97 (0.90–1.04) | 2250 (59.5) | 1178 (63.6) | 0.96 (0.82–1.13) |
| Missing data | 3 (0.0) | 528 (9.1) | ||||
| Age, yrs, mean (SD) | 44.3 (10.7) | 44.0 (11.8) | 45.1 (4.8) | 44.4 (10.6) | ||
| <30 | 612 (9.0) | 669 (11.5) | 1 (reference) | 239 (6.3) | 168 (9.1) | 1 (reference) |
| 30–39 | 1766 (26.1) | 1309 (22.5) | 1.47 (1.29–1.68)* | 939 (24.8) | 474 (25.6) | 1.33 (0.99–1.78) |
| 40–49 | 2070 (30.6) | 1433 (24.6) | 1.58 (1.39–1.80)* | 1242 (32.9) | 558 (30.1) | 1.54 (1.15–2.06)* |
| 50–59 | 1768 (26.1) | 1301 (22.3) | 1.49 (1.30–1.69)* | 1090 (28.8) | 515 (27.8) | 1.61 (1.20–2.18)* |
| >59 | 555 (8.2) | 594 (10.2) | 1.02 (0.87–1.20) | 269 (7.1) | 138 (7.4) | 1.56 (1.04–2.35)* |
| Missing data | 3 (0.0) | 523 (9.0) | ||||
| Classification of occupation | ||||||
| Legislators, senior officials, and managers | 640 (9.4) | – | – | 420 (11.1) | 123 (6.6) | 1 (reference) |
| Professionals | 1812 (26.7) | – | – | 1063 (28.1) | 411 (22.2) | 0.96 (0.70–1.30) |
| Technicians and associate professionals | 2345 (34.6) | – | – | 1278 (33.8) | 693 (37.4) | 0.68 (0.50–0.91)* |
| Clerks | 554 (8.2) | – | – | 292 (7.7) | 178 (9.6) | 0.59 (0.41–0.86)* |
| Service workers and shop and market sales workers | 1146 (16.9) | – | – | 592 (15.7) | 347 (18.7) | 0.66 (0.46–0.94)* |
| Skilled agricultural and fishery workers | 2 (0.0) | – | – | 1 (0.0) | 1 (0.1) | 0.37 (0.02–6.20) |
| Craft and related trades workers | 85 (1.3) | – | – | 43 (1.1) | 24 (1.3) | 0.54 (0.26–1.10) |
| Plant and machine operators and assemblers | 12 (0.2) | – | – | 1 (0.0) | 9 (0.5) | – |
| Elementary occupations | 94 (1.4) | – | – | 51 (1.3) | 30 (1.6) | 0.52 (0.26–1.06) |
| Armed forces and unspecified | 3 (0.0) | – | – | 2 (0.1) | 1 (0.1) | – |
| Missing data | 81 (1.2) | – | – | 36 (1.0) | 36 (1.9) | |
| Skill level | ||||||
| Competence equivalent to ≥4 yrs of higher education (>15 yrs) | 1812 (26.7) | – | – | 1063 (28.1) | 411 (22.2) | 1 (reference) |
| Competence equivalent to 1–3 yrs of higher education (13–15 yrs) | 2345 (34.6) | – | – | 1278 (33.8) | 693 (37.4) | 0.70 (0.57–0.86)* |
| Competence equivalent to high school (10–12 yrs) | 1799 (26.6) | – | – | 929 (24.6) | 559 (30.2) | 0.63 (0.50–0.81)* |
| Occupations that do not require high school (<10 yrs) | 94 (1.4) | – | – | 51 (1.3) | 30 (1.6) | 0.54 (0.27–1.06) |
| Occupations with unspecified requirements for competence | 643 (9.5) | – | – | 422 (11.2) | 124 (6.7) | 1.06 (0.78–1.44) |
| Missing data | 81 (1.2) | – | – | 36 (1.0) | 36 (1.9) | |
| The work ability index, mean (SD) | 41.8 (4.9) | 41.9 (4.8) | 41.5 (5.0) | |||
| (continues) | ||||||
| Invited to the First Survey (N = 12,603) | Invited to the First and Second surveys (N = 9304) | |||||
|---|---|---|---|---|---|---|
| Respondents at Baselinea (n = 6774) | Nonresponders at Baseline (n = 5829) | Nonresponse Analysis | Respondents at the First and Second surveysb (n = 3779) | Dropouts (n = 1853) | Attrition Analysisc | |
| n (%) | n (%) | OR (95% CI) | n (%) | n (%) | OR (95% CI) | |
| Low (<37 points) | 645 (9.5) | 340 (9.0) | 204 (11.0) | 1 (reference) | ||
| Moderate/high (≥37 points) | 4262 (62.9) | 2444 (64.7) | 1101 (59.4) | 1.16 (0.97–1.45) | ||
| Missing data | 1867 (27.6) | 995 (26.3) | 548 (29.6) | |||
| Perceived work ability, mean (SD) | 8.5 (1.7) | 8.6 (1.6) | 8.5 (1.7) | |||
| Low (<8 points) | 1204 (17.8) | 626 (16.6) | 352 (19.0) | 1 (reference) | ||
| Moderate/high (≥8 points) | 5545 (81.9) | 3144 (83.2) | 1491 (80.5) | 1.15 (0.97–1.37) | ||
| Missing data | 25 (0.4) | 9 (0.2) | 10 (0.5) | |||
| Work ability prognosis, mean (SD) | 2.9 (0.3) | 2.9 (0.3) | 2.9 (0.3) | |||
| Low (categories 1 and 2) | 469 (6.9) | 213 (5.6) | 145 (7.8) | 1 (reference) | ||
| High (category 3) | 5593 (82.6) | 3174 (84.0) | 1504 (81.2) | 1.20 (0.92–1.58) | ||
| Missing data | 712 (10.5) | 392 (10.4) | 204 (11.0) | |||
| Exposures, mean (SD) | ||||||
| Decision demands, | 3.5 (0.7) | 3.5 (0.7) | 3.5 (0.7) | 0.96 (0.85–1.08) | ||
| Quantitative demands | 3.0 (0.8) | 3.0 (0.7) | 2.9 (0.8) | 0.96 (0.86–1.07) | ||
| Role clarity | 4.3 (0.7) | 4.2 (0.7) | 4.3 (0.7) | 0.85 (0.75–0.95)* | ||
| Role conflict | 2.5 (0.8) | 2.5 (0.8) | 2.4 (0.8) | 1.02 (0.91–1.14) | ||
| Positive challenge | 4.0 (0.8) | 4.1 (0.7) | 4.0 (0.8) | 1.03 (0.91–1.16) | ||
| Control over work intensity | 3.3 (1.1) | 3.4 (1.0) | 3.2 (1.0) | 1.09 (0.99–1.19) | ||
| Decision control | 3.0 (0.8) | 3.1 (0.8) | 3.0 (0.8) | 1.10 (0.98–1.25) | ||
| Predictability during the next month | 4.2 (0.7) | 4.3 (0.7) | 4.2 (0.8) | 1.04 (0.93–1.16) | ||
| Support from immediate superior | 3.9 (0.9) | 3.9 (0.9) | 3.9 (0.9) | 1.04 (0.91–1.19) | ||
| Empowering leadership | 3.1 (1.0) | 3.2 (1.0) | 3.1 (1.0) | 1.03 (0.93–1.14) | ||
| Fair leadership | 3.9 (0.9) | 4.0 (0.8) | 3.9 (0.9) | 1.10 (0.98–1.24) | ||
| Innovative climate | 3.6 (0.8) | 3.7 (0.7) | 3.6 (0.8) | 0.95 (0.82–1.10) | ||
| Social climate | 3.8 (0.7) | 3.8 (0.7) | 3.8 (0.8) | 1.17 (1.03–1.34)* | ||
| Human resource primacy | 3.1 (0.9) | 3.1 (0.9) | 3.1 (0.9) | 0.89 (0.80–1.00) | ||
| Physical workload | 1.6 (0.8) | 1.6 (0.8) | 1.7 (0.8) | 1.18 (1.05–1.33)* | ||
| Working with arms raised to or above shoulder level | 1.5 (0.8) | 1.5 (0.8) | 1.5 (0.9) | 0.98 (0.88–1.10) | ||
aCompleted minimum one exposure measure and minimum one of the three work ability outcome measures.
bCompleted minimum one exposure measure at baseline and minimum one of the three work ability outcome measures twice (at baseline and follow-up).
cAdjusted for variables found significant (P < 0.05) in univariate attrition analysis.
*P < 0.05.
CI, confidence interval; OR, odds ratio; SD, standard deviation.