Table 2

Results of meta-regression childhood autism (18 studies)
Univariate analyses
Covariate Categories of covariate Number of studies Odds ratio 95%CI P value Variance explained (%)
No covariates 18
Year (continuous) 18 1.04 (0.93, 1.17) 0.43 −5.09
Year (categorical) 2000 to 2004 5 1.00 - - −10.92
2005 to 2009 6 1.13 (0.42, 3.08) 0.80
2010 to 2011 7 1.44 (0.55, 3.77) 0.43
Age group <4 5 1.00 - - 56.00
4 8 1.06 (0.56, 2.02) 0.84
>4 5 0.33 (0.16, 0.68) 0.005
Area Urban 9 1.00 - - −8.40
Mixed or rural 8 0.81 (0.38, 1.75) 0.57
Rural 1 0.64 (0.09, 4.37) 0.62
Sample group ≤5000 5 1.00 - - 7.43
5000 to 7500 5 1.43 (0.54, 3.80) 0.44
>7500 8 0.74 (0.30, 1.80) 0.48
Sample source Population-based 13 1.00 1.00 −0.19
Schools or kindergartens 4 1.44 (0.60, 3.48) 0.39
Screening method Interview 15 1.00 - - −0.89
Questionnaire 2 1.64 (0.54, 4.98) 0.36
Screening tool CABS 12 1.00 - 76.99
ABC 3 0.21 (0.11, 0.38) <0.001
CHAT 3 1.25 (0.71, 2.20) 0.42
Time Once 13 1.00 1.00 −2.10
Twice 4 1.40 (0.60, 3.27) 0.41
Screening informant Clinician 8 1.00 - - −13.86
Parent 3 0.93 (0.31, 2.75) 0.88
Research 6 0.90 (0.38, 2.10) 0.79
Diagnostic criteria CCMD-2-R 5 1.00 - - −5.34
DSM-III-R/DSM-IV/ICD-10 12 1.23 (0.52, 2.87) 0.62
Diagnostic tool None 6 1.00 - 2.54
CABS 11 1.51 (0.71, 3.21) 0.27
Diagnostic informant Clinician 13 1.00 - - 8.19
Researcher 4 0.47 (0.19, 1.17) 0.10
Multivariable analyses
Age group <4 5 1.00 - - 80.7
4 8 1.61 (0.68, 3.81) 0.26
>4 5 1.03 (0.34, 3.04) 0.96
Screening tool CABS 12 1.00 1.00 -
ABC 3 0.29 (0.12, 0.69) 0.009
CHAT 3 1.79 (0.70, 4.55) 0.20

ABC, Autism Behavior Checklist; CABS, Clancy Autism Behavior Scale; CCMD-2-R, Chinese Classification of Mental Disorders, 2nd edition, revised; CHAT, Checklist for Autism in Toddlers; CI, confidence interval; SM-III-R, Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised; DSM-IV, Diagnostic and Statistical Manual of Mental Disorders, 4th edition; ICD-10, International Classification of Diseases, 10th revision;-, data not available.

Sun et al.

Sun et al. Molecular Autism 2013 4:7   doi:10.1186/2040-2392-4-7

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