Introduction
Materials and methods
Setting
Study population
Data collection
Variables of interest
Statistical analyses
Results
Study sample
Age, August 2012 | Boys, n (%) | Girls, n (%) | Total n (%) |
---|---|---|---|
490 (48.0) | 530 (52.0) | 1020 (100.0) | |
9 | 29 (41.4) | 41 (58.6) | 70 (6.9) |
10 | 90 (41.5) | 127 (58.5) | 217 (21.3) |
11 | 114 (49.1) | 118 (50.9) | 232 (22.8) |
12 | 120 (55.0) | 98 (45.0) | 218 (21.4) |
13 | 86 (46.2) | 100 (53.8) | 186 (18.2) |
14–15 | 51 (52.6) | 46 (47.4) | 97 (9.5) |
Mean age (SD) | 11.6 (SD 1.4) | 11.4 (SD 1.4) | 11.5 (SD 1.4) |
Is LE pain within the preceding weeks associated with an incident event of spinal pain?
Primary analyses: outcome spinal pain1 | Reversed analyses: outcome lower extremity pain2 | p value for the difference between primary and reversed analyses | ||
---|---|---|---|---|
Lower extremity pain within the preceding | Odds ratio (95% CI) | Spinal pain within the preceding: | Odds ratio (95% CI) | |
1 week | 0.87 (0.58 to 1.31) | 1 week | 1.26 (0.84 to 1.87) | 0.19 |
2 weeks | 0.93 (0.65 to 1.33) | 2 weeks | 1.14 (0.79 to 1.65) | 0.41 |
4 weeks | 1.11 (0.82 to 1.49) | 4 weeks | 1.18 (0.86 to 1.62) | 0.75 |
8 weeks | 1.23 (0.94 to 1.59) | 8 weeks | 1.09 (0.82 to 1.44) | 0.50 |
12 weeks | 1.34 (1.05 to 1.70) | 12 weeks | 1.15 (0.89 to 1.47) | 0.34 |
20 weeks | 1.39 (1.11 to 1.75) | 20 weeks | 1.12 (0.89 to 1.40) | 0.14 |
Primary analyses: outcome spinal pain1 | Reversed analyses: outcome lower extremity pain2 | p value for the difference between primary and reversed analyses | ||
---|---|---|---|---|
Proportion of weeks with lower extremity pain | Odds ratio (95% CI) | Proportion of weeks with spinal pain | Odds ratio (95% CI) | |
0% | 1.00 | 0% | 1.00 | |
1–50% | 1.35 (1.06 to 1.72) | 1–50% | 1.15 (0.90 to 1.45) | 0.29 |
51–100% | 1.59 (1.04 to 2.43) | 51–100% | 0.94 (0.51 to 1.72) | 0.11 |
Trend | 1.30 (1.10 to 1.54) | 1.07 (0.91–1.26) | 0.09 |
Primary analysis: outcome spinal pain 1 | Reversed analysis: outcome lower extremity pain2 | p value for the difference between primary and reversed analyses | ||||
---|---|---|---|---|---|---|
Proportion of weeks with lower extremity pain1 |
n
| Hazard ratio (95% CI) | Proportion of weeks with lower extremity pain2 |
n
| Hazard ratio (95% CI) | |
0% | 1008 | 1.00 | 0% | 1006 | 1.00 | |
1–50% | 515 | 1.62 (1.24 to 2.11) | 1–50% | 168 | 1.42 (1.06 to 1.92) | 0.51 |
51–100% | 122 | 2.07 (1.34 to 3.20) | 51–100% | 34 | 1.51 (0.82 to 1.78) | 0.40 |
Trend | 1645 | 1.48 (1.24 to 1.89) | 1208 | 1.32 (1.06 to 1.65) | 0.38 |
Is spinal pain within the preceding weeks associated with an incident event of LE pain?
Sex differences
Primary analyses: outcome spinal pain1 | Reversed analyses: outcome lower extremity pain2 | ||||||||
Lower extremity pain within the preceding: | Girls | Boys | Spinal pain within the preceding: | Girls | Boys | ||||
n
| Odds ratio (95% CI) |
n
| Odds ratio (95% CI) |
n
| Odds ratio (95% CI) |
n
| Odds ratio | ||
1 week | 291 | 0.80 (0.45 to 1.41) | 276 | 0.96 (0.53 to 1.73) | 1 week | 198 | 1.11 (0.66 to 1.88) | 166 | 1.50 (0.81 to 2.76) |
2 weeks | 299 | 0.89 (0.54 to 1.46) | 281 | 0.97 (0.58 to 1.62) | 2 weeks | 201 | 0.98 (0.59 to 1.61) | 169 | 1.41 (0.82 to 2.44) |
4 weeks | 310 | 1.13 (0.75 to 1.72) | 293 | 1.07 (0.69 to 1.66) | 4 weeks | 209 | 1.01 (0.66 to 1.57) | 178 | 1.43 (0.90 to 2.27) |
8 weeks | 325 | 1.32 (0.92 to 1.89) | 314 | 1.14 (0.78 to 1.65) | 8 weeks | 229 | 1.02 (0.70 to 1.49) | 189 | 1.18 (0.78 to 1.79) |
12 weeks | 336 | 1.46 (1.04 to 2.04) | 325 | 1.23 (0.87 to 1.73) | 12 weeks | 242 | 0.98 (0.69 to 1.40) | 199 | 1.37 (0.95 to 1.95) |
20 weeks | 360 | 1.58 (1.14 to 2.18) | 353 | 1.23 (0.90 to 1.70) | 20 weeks | 262 | 0.92 (0.67 to 1.27) | 218 | 1.38 (1.00 to 1.90) |
Proportion of weeks with lower extremity pain | Proportion of weeks with spinal pain | ||||||||
0% | 486 | 1.00 | 457 | 1.00 | 0% | 507 | 1.00 | 482 | 1.00 |
1–50% | 347 | 1.57 (1.11 to 2.22) | 347 | 1.18 (0.84 to 1.66) | 1–50% | 257 | 0.91 (0.64 to 1.29) | 214 | 1.45 (1.05 to 2.00) |
> 50% | 104 | 1.61 (0.92 to 2.81) | 71 | 1.61 (0.84 to 1.65) | > 50% | 58 | 0.98 (0.50 to 1.92) | 21 | 0.67 (0.17 to 2.72) |
Hazard ratio (95% CI) | Hazard ratio (95% CI) | ||||||||
0% | 551 | 1.00 | 328 | 1.00 | 0% | 349 | 1.00 | 328 | 1.00 |
1–50% | 195 | 1.88 (1.27 to 2.80) | 221 | 1.42 (0.99 to 2.04) | 1–50% | 84 | 1.33 (0.85 to 2.05) | 70 | 1.53 (1.02 to 2.31) |
> 50% | 63 | 2.54 (1.27 to 2.80) | 39 | 1.54 (0.77 to 3.09) | > 50% | 21 | 2.10 (1.08 to 4.09) | 8 | 0.38 (0.05 to 2.73) |