Table 2.
Odds ratios for pooled surgery exposures using a random effects model
|
Exposure |
Included studies (n) |
MS case group (n) |
Control group (n) |
Total (n) |
Level of heterogeneity I2 (χ2 p) |
Pooled OR (95% CI) |
Test for overall effect |
|---|---|---|---|---|---|---|---|
| Z ( p ) | |||||||
| Tonsillectomy ≤ 20 years |
12 |
4,414 |
4,422 |
8,836 |
44% (0.05) |
1.32 (1.08-1.61)* |
2.76 (0.006) * |
| Tonsillectomy > 20 years |
9 |
1,801 |
1,618 |
3,419 |
32% (0.16) |
1.20 (0.94-1.53) |
1.45 (0.15) |
| Appendectomy ≤ 20 years |
7 |
21,218 |
205,124 |
226,342 |
0% (0.54) |
1.16 (1.01-1.34)* |
2.06 (0.04) * |
| Appendectomy > 20 years |
5 |
21,360 |
205,021 |
226,381 |
46% (0.11) |
1.26 (0.92-1.72) |
1.43 (0.15) |
| Adenoidectomy ≤ 20 years |
3 |
458 |
636 |
1,094 |
35% (0.21) |
1.06 (0.68-1.68) |
0.27 (0.79) |
| Surgery ≤ 20 years |
4 |
485 |
1,202 |
1,687 |
19% (0.30) |
0.95 (0.70-1.31) |
0.29 (0.77) |
| Surgery > 20 years | 15 | 1,099 | 1,371 | 2,470 | 71% (0.0001) | 1.19 (0.83-1.70) | 0.94 (0.35) |
* Indicates statistically significant results at p < 0.05.
CI = confidence interval, MS = multiple sclerosis, OR = odds ratio.