Characteristics of participants by intervention group
| Ergonomic training only | Ergonomic training and trackball | Ergonomic training + armboard | Ergonomic training + trackball + armboard | p Value* | |
|---|---|---|---|---|---|
| n = 46 | n = 45 | n = 46 | n = 45 | ||
| Mean (SD) or % | Mean (SD) or % | Mean (SD) or % | Mean (SD) or % | ||
| *χ2 for categorical measures, ANOVA for continuous measures, and Bartlett’s test for equal variances for psychosocial variables. | |||||
| †Pain score scale from 0 = no pain to 10 = unbearable pain. | |||||
| Demographics | |||||
| Gender: female | 94% | 98% | 100% | 89% | 0.08 |
| Age (years) | 40.0 (11.6) | 40.5 (12.4) | 38.9 (12.1) | 40.7 (12.2) | 0.89 |
| Body mass index | 27.6 (6.20) | 28.2 (6.62) | 29.9 (7.69) | 30.1 (8.95) | 0.30 |
| Right handed | 89% | 96% | 89% | 96% | 0.45 |
| Right handed mouse use | 100% | 96% | 96% | 100% | 0.25 |
| Single | 35% | 29% | 43% | 38% | 0.54 |
| Educational level | 0.07 | ||||
| High school | 20% | 27% | 20% | 36% | |
| Some college | 33% | 40% | 57% | 40% | |
| Completed college | 48% | 33% | 24% | 24% | |
| Ethnicity | 0.25 | ||||
| African American | 13% | 18% | 30% | 22% | |
| Asian or Pacific Islander | 26% | 16% | 13% | 16% | |
| Hispanic | 9% | 16% | 15% | 11% | |
| White | 52% | 51% | 37% | 51% | |
| Native American | 0% | 0% | 4% | 0% | |
| Medical history | |||||
| Systemic comorbidity | 24% | 31% | 20% | 20% | 0.54 |
| Regional disorders | 65% | 76% | 57% | 62% | 0.28 |
| Low pack pain | 43% | 47% | 46% | 36% | 0.71 |
| Lost work days in past year | 0.36 (0.96) | 2.99 (13.7) | 4.22 (16.5) | 0.58 (1.25) | 0.25 |
| Previous surgery in upper body | 11% | 18% | 9% | 9% | 0.49 |
| Pregnant | 0% | 5% | 0% | 3% | 0.29 |
| Oopherectomy | 9% | 9% | 2% | 8% | 0.51 |
| Menopausal | 21% | 27% | 17% | 13% | 0.38 |
| Pain medication | 59% | 36% | 46% | 58% | 0.09 |
| Antidepressant medication | 9% | 9% | 17% | 4% | 0.21 |
| Current smoker | 11% | 16% | 9% | 22% | 0.26 |
| Weekly exercise | 63% | 58% | 46% | 64% | 0.25 |
| Hand intensive recreational activity (hours/week) | 12.8 (8.94) | 16.7 (11.2) | 15.2 (16.4) | 16.1 (13.5) | 0.47 |
| Aerobic activity (hours/week) | 0.25 (0.92) | 0.22 (1.06) | 0.37 (1.34) | 0.43 (1.70) | 0.85 |
| Pre-intervention upper body pain scores† | |||||
| Neck/shoulder pain | 2.1 (2.2) | 2.9 (2.8) | 2.6 (2.8) | 2.0 (2.4) | 0.28 |
| Right upper extremity pain | 2.0 (2.4) | 2.1 (2.6) | 2.7 (3.1) | 2.4 (2.8) | 0.52 |
| Left upper extremity pain | 1.4 (2.2) | 1.6 (2.3) | 1.9 (2.8) | 1.0 (1.9) | 0.28 |
| Neck/shoulder pain >5 | 7% | 22% | 13% | 11% | 0.16 |
| Right upper extremity pain >5 | 13% | 16% | 24% | 16% | 0.53 |
| Left upper extremity pain >5 | 11% | 11% | 11% | 4% | 0.64 |
| Mean post-intervention upper body pain scores | |||||
| Neck/shoulder pain | 1.8 (1.9) | 2.2 (2.2) | 1.8 (2.1) | 1.1 (1.3) | |
| Right upper extremity pain | 1.9 (2.1) | 1.9 (1.8) | 1.7 (2.2) | 1.3 (1.8) | |
| Left upper extremity pain | 1.4 (1.8) | 1.0 (1.3) | 1.3 (2.1) | 0.8 (1.6) | |
| Workplace factors | |||||
| Worksite A | 83% | 82% | 83% | 84% | 0.99 |
| Job title: registered nurse | 54% | 42% | 41% | 42% | 0.54 |
| Seniority (months) | 20.6 (13.6) | 23.2 (13.3) | 21.9 (14.0) | 23.9 (12.9) | 0.65 |
| Typing speed (words/minute) | 45.7 (11.6) | 47.0 (15.7) | 44.9 (11.1) | 46.3 (14.8) | 0.90 |
| Work hours per week | 33.0 (5.51) | 32.6 (6.86) | 33.7 (6.34) | 33.9 (5.74) | 0.76 |
| Computer use (hours/week) | 31.5 (5.48) | 31.7 (6.81) | 32.2 (7.13) | 31.9 (5.71) | 0.96 |
| Total break (minutes/day) | 53.7 (16.3) | 41.7 (23.2) | 47.7 (23.3) | 48.7 (21.0) | 0.06 |
| Iso-strain | 0.40 (0.10) | 0.41 (0.09) | 0.41 (0.09) | 0.41 (0.10) | 0.82 |
| Composite Psychological Strain | −0.06 (0.96) | −0.04 (0.88) | 0.19 (1.18) | 0.10 (0.96) | 0.51 |