Table 3.
Association between back pain (outcome) and exposure variables (exercise, behaviour, heredity and posture), depicted as relative risk – Teutônia, Rio Grande do Sul, Brazil (n = 525).
| Variables | Bivariate model Unadjusted RR (95% CI) |
p a | Multivariate model Adjusted RR (95% CI) |
p a |
|---|---|---|---|---|
| Control variables | ||||
| Age (baseline; years) | ||||
| 11–12 | 1 | 0.929 | ||
| 13–14 | 1.00 (0.96–1.05) | |||
| 15–16 | 0.98 (0.90–1.07) | |||
| Sex | ||||
| Male | 1 | <0.001 | 1 | <0.001 |
| Female | 1.08 (1.04–1.13) | 1.08 (1.04–1.13) | ||
| Exposure variables | ||||
| Exercise | ||||
| Physical exercise | ||||
| Yes | 1 | 0.946 | – | |
| No | 1.00 (0.94–1.07) | – | ||
| Physical exercise weekly frequencyb (days/week) | ||||
| 1–2 | 1 | 0.116 | – | |
| 3–4 | 0.96 (0.91–1.01) | – | ||
| ⩾5 | 0.95 (0.90–1.01) | – | ||
| Competitive exerciseb | ||||
| Yes | 1 | 0.156 | – | |
| No | 1.03 (0.99–1.08) | – | ||
| Behaviour | ||||
| Time spent watching television per day (hours) | ||||
| 0–1 | 1 | <0.001 | 1 | 0.002 |
| 2–5 | 0.95 (0.91–0.99) | 0.96 (0.92–1.01) | ||
| ⩾6 | 1.08 (1.01–1.14) | 1.07 (1.01–1.13) | ||
| Time spent using computer per day (hours) | ||||
| 0–1 | 1 | 0.094 | 1 | 0.115 |
| 2–5 | 0.98 (0.94–1.03) | 1.00 (0.96–1.05) | ||
| ⩾6 | 1.06 (0.97–1.13) | 1.06 (0.99–1.14) | ||
| Time sleeping per night (hours/day) | ||||
| 0–7 | 1 | 0.018 | 1 | 0.152 |
| 8–9 | 0.94 (0.90–0.98) | 0.96 (0.92–1.01) | ||
| ⩾10 | 0.97 (0.90–1.04) | 0.96 (0.89–1.04) | ||
| Read and/or study in bed | ||||
| No | 1 | 0.019 | 1 | 0.500 |
| Sometimes | 1.02 (0.97–1.08) | 1.01 (0.96–1.07) | ||
| Yes | 1.07 (1.02–1.13) | 1.03 (0.98–1.09) | ||
| Hereditary | ||||
| Parents with back pain | ||||
| No | 1 | <0.001 | 1 | <0.001 |
| Yes | 1.20 (1.14–1.26) | 1.16 (1.10–1.23) | ||
| Postural | ||||
| Sleeping | ||||
| Supine | 1 | 0.059 | 1 | 0.215 |
| Lateral decubitus | 1.01 (0.94–1.09) | 1.04 (0.96–1.12) | ||
| Prone | 1.06 (0.98–1.15) | 1.06 (0.98–1.14) | ||
| Sitting posture to write | ||||
| Adequate | 1 | 0.049 | 1 | 0.539 |
| Inadequate | 1.07 (1.01–1.14) | 1.02 (0.96–1.09) | ||
| Sitting posture on a bench | ||||
| Adequate | 1 | 0.274 | – | |
| Inadequate | 1.04 (0.97–1.11) | – | ||
| Sitting posture to use computer | ||||
| Adequate | 1 | 0.005 | 1 | 0.503 |
| Inadequate | 1.08 (1.02–1.13) | 1.02 (0.97–1.07) | ||
| Posture to lift object from floor | ||||
| Adequate | 1 | 0.808 | – | |
| Inadequate | 0.99 (0.94–1.05) | – | ||
| Way to carry backpack | ||||
| Adequate (symmetrical on both shoulders) | 1 | <0.001 | 1 | 0.037 |
| Inadequate (asymmetric) | 1.09 (1.05–1.13) | 1.04 (1.01–1.08) | ||
CI: confidence interval.
Generalized estimating equations were used to perform a Poisson regression model with robust variance errors. We used relative risk (RR) with their respective 95% CIs to measure effects (α = 0.05). The multivariate analysis was adjusted for sex and age and included the exposure variables (p < 0.10 in the bivariate analysis). Bold data reflect statistical significance (p < 0.05).
a
Significant association (p < 0.05).
b
Related only to students in whom the variable was applicable.