TABLE 2—
Summary of Traditional Meta-Analyses of Studies of Mechanical Risk Factors in the Workplace and Low Back Pain for Unadjusted Odds Ratios for Each of the Selected Outcome–Exposure Combinations, Using the Algorithmic Translation of Exposure
| Outcome–Exposure Combinations | Studies, No. | Fixed Effects OR (95% CI) | Pfixed | Random Effects OR (95% CI) | Prandom | Qa | PQ | I2, %b |
| LBP in the past 6 mo to 2 y | ||||||||
| Posture 1A | 4 | 1.27 (1.16, 1.40) | <.001 | 1.27 (1.16, 1.40) | <.001 | 1.4 | .70 | 0.0 |
| Posture 1B | 3 | 1.14 (1.08, 1.21) | <.001 | 1.14 (1.08, 1.21) | <.001 | 1.7 | .43 | 0.0 |
| Posture 1C | 7 | 1.33 (1.19, 1.50) | <.001 | 1.36 (1.07, 1.73) | .01 | 16.2 | .01 | 62.9 |
| Posture 2A | 5 | 1.27 (1.16, 1.39) | <.001 | 1.27 (1.16, 1.39) | <.001 | 1.4 | .84 | 0.0 |
| Posture 2B | 5 | 1.18 (1.15, 1.21) | <.001 | 1.18 (1.15, 1.21) | <.001 | 3.8 | .43 | 0.0 |
| Posture 2C | 14 | 1.69 (1.56, 1.82) | <.001 | 1.68 (1.39, 2.04) | <.001 | 42.3 | <.001 | 69.3 |
| Force 1C | 14 | 1.61 (1.52, 1.71) | <.001 | 1.40 (1.20, 1.62) | <.001 | 58.3 | <.001 | 77.7 |
| Force 2C | 11 | 1.43 (1.32, 1.55) | <.001 | 1.42 (1.30, 1.55) | <.001 | 10.7 | .38 | 6.9 |
| Current LBP | ||||||||
| Posture 2A | 2 | 1.20 (0.96, 1.51) | .11 | 1.20 (0.96, 1.51) | .11 | 0.2 | .69 | 0.0 |
| Posture 2B | 4 | 1.20 (1.16, 1.24) | <.001 | 1.20 (1.16, 1.24) | <.001 | 2.3 | .51 | 0.0 |
| Posture 2C | 8 | 1.70 (1.52, 1.91) | <.001 | 1.84 (1.28, 2.63) | <.001 | 39.3 | <.001 | 82.2 |
| Sick leave attributable to LBP | ||||||||
| Posture 2A | 3 | 1.65 (1.23, 2.23) | <.001 | 1.47 (0.59, 3.66) | .4 | 12.1 | .002 | 83.5 |
| Posture 2B | 5 | 1.19 (1.09, 1.30) | <.001 | 1.19 (1.09, 1.30) | <.001 | 0.6 | .96 | 0.0 |
| Posture 2C | 8 | 2.26 (1.68, 3.03) | <.001 | 2.03 (1.26, 3.38) | .004 | 11.8 | .11 | 40.7 |
| Force 1C | 7 | 2.02 (1.66, 2.46) | <.001 | 1.95 (1.53, 2.49) | <.001 | 7.5 | .28 | 19.7 |
| Force 2C | 7 | 2.11 (1.73, 2.57) | <.001 | 2.11 (1.73, 2.57) | <.001 | 3.3 | .77 | 0.0 |
Note. CI = confidence interval; LBP = low back pain; OR = odds ratio. Posture 1 = trunk flexion; posture 2 = nonneutral posture; force 1 = lifting; force 2 = heavy lifting; “A” exposures represent the percentage of a workday spent in a nonneutral posture or exerting a force; “B” exposures represent the percentage of job tasks requiring a nonneutral posture or exerting a force; “C” exposures represent ever experiencing a nonneutral posture or exerting a force. ORs for “A” and “B” exposures represent the OR for a difference in exposure of 20% (approximately 1.6 hours in an 8-hour workday). ORs for “C” exposures represent the OR for any exposure compared with no exposure.
Q is the χ2 test for heterogeneity.
I2 is the percentage of the total variability in a set of effect sizes because of true heterogeneity.