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Table 3 Sensitivity analyses and stratified meta-regression for assessing heterogeneity among case–control studies looking at the exposures tonsillectomy in childhood and “surgery” premorbid 1

From: Surgery and risk for multiple sclerosis: a systematic review and meta-analysis of case–control studies

Exposure variables

Tonsillectomy - childhood

Surgery - premorbid

 

Studies

Sub-group

Meta-regression

Studies

Sub-group

Meta-regression

 

n

Total ( n)

OR (95% CI) 2

p

β (95% CI) 3

n

Total ( n)

OR (95% CI) 2

p

β (95% CI) 3

Population-level characteristics

Latitude

12

8,836

1.32 (1.08-1.61)*

0.79

1.00 (0.96-1.03)

15

2,470

1.19 (0.83-1.70)

0.89

1.00 (0.97-1.03)

(geographic)

Female: Male

10

8,218

1.39 (1.15-1.68)*

0.45

1.20 (0.71-2.04)

14

2,362

1.22 (0.84-1.79)

0.91

0.98 (0.64-1.48)

Mean age of MS onset

9

2,818

1.17 (0.85-1.61)

0.51

0.98 (0.90-1.06)

10

1,551

1.12 (0.77-1.63)

0.53

0.94 (0.77-1.16)

Study-level characteristics

NOS score

11

8,480

1.29 (1.03-1.60)*

0.77

0.98 (0.85-1.13)

15

2,470

1.19 (0.83-1.70)

0.58

0.89 (0.58-1.37)

NOS score (< 6 vs. ≥ 6)

12

8,836

1.32 (1.08-1.61)*

0.60

0.88 (0.51-1.50)

15

2,470

1.19 (0.83-1.70)

0.84

0.84 (0.13-5.57)

Language (English vs. non-English)

12

8,836

1.32 (1.08-1.61)*

0.10

0.62 (0.34-1.12)

15

2,470

1.19 (0.83-1.70)

0.73

0.78 (0.17-3.61)

Pub type (published vs. unpublished)

12

8,836

1.32 (1.08-1.61)*

0.09

0.50 (0.22-1.13)

15

2,470

1.19 (0.83-1.70)

N/A4

Number of covariates 5 (≤ 2 vs. > 2)

12

8,836

1.32 (1.08-1.61)*

0.04

1.64 (1.02-2.62)*

15

2,470

1.19 (0.83-1.70)

0.73

0.88 (0.39-1.96)

Sample size (≤ 100 vs. > 100)

12

8,836

1.32 (1.08-1.61)*

0.54

0.52 (0.05-5.27)

15

2,470

1.19 (0.83-1.70)

0.56

0.76 (0.29-2.01)

MS cases (≤ 100 vs. > 100)

12

8,836

1.32 (1.08-1.61)*

0.37

1.32 (0.68-2.60)

15

2,470

1.19 (0.83-1.70)

0.70

0.87 (0.40-1.90)

  1. 1 All analyses weighted by sample size.
  2. 2 OR (95% CI) were calculated using the random effects model in RevMan.
  3. 3 β (95% CI) were calculated using the study level log OR and the SE of the estimate (calculated in RevMan) by univariate random effects meta-regression in STATA 12 using the megareg command.
  4. 4 All studies were published – analysis not warranted.
  5. 5 Number of potentially confounding variables adjusted for in individual studies.
  6. CI = confidence interval, MS = multiple sclerosis, NOS = Newcastle-Ottawa Scale, OR = odds ratio, Pub = Publication, SE = Standard error.
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BMC Neurology

ISSN: 1471-2377

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