Comparison 9. Safety: autism spectrum disorders.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
9.1 Cohort studies	3		Rate Ratio (IV, Random, 95% CI)	Subtotals only
9.1.1 All children MMR	2		Rate Ratio (IV, Random, 95% CI)	0.93 [0.85, 1.01]
9.1.2 Autism risk (low) MMR	1		Rate Ratio (IV, Random, 95% CI)	1.00 [0.89, 1.14]
9.1.3 Autism risk (moderate/high) MMR	1		Rate Ratio (IV, Random, 95% CI)	0.80 [0.64, 0.98]
9.2 Case‐control	4		Odds Ratio (IV, Random, 95% CI)	Subtotals only
9.2.1 Any age MMR	3		Odds Ratio (IV, Random, 95% CI)	0.62 [0.36, 1.09]
9.2.2 Before age 18 months MMR	2		Odds Ratio (IV, Random, 95% CI)	0.91 [0.75, 1.11]
9.2.3 After age 18 months MMR	1		Odds Ratio (IV, Random, 95% CI)	0.80 [0.61, 1.05]
9.2.4 Before age 36 months MMR	2		Odds Ratio (IV, Random, 95% CI)	0.94 [0.74, 1.18]
9.2.5 After age 36 months MMR	1		Odds Ratio (IV, Random, 95% CI)	0.77 [0.55, 1.08]
9.3 Self‐controlled case series/person‐time cohort	1		Rate Ratio (IV, Random, 95% CI)	Subtotals only
9.3.1 ASD diagnosis < 12 months MMR	1		Rate Ratio (IV, Random, 95% CI)	0.94 [0.60, 1.47]
9.3.2 ASD diagnosis < 24 months MMR	1		Rate Ratio (IV, Random, 95% CI)	1.09 [0.79, 1.51]
9.3.3 Regression < 2 months MMR	1		Rate Ratio (IV, Random, 95% CI)	0.92 [0.38, 2.22]
9.3.4 Regression < 4 months MMR	1		Rate Ratio (IV, Random, 95% CI)	1.00 [0.52, 1.94]
9.3.5 Regression < 6 months MMR	1		Rate Ratio (IV, Random, 95% CI)	0.85 [0.45, 1.60]
9.4 Case only ecological method	1		Rate Ratio (IV, Random, 95% CI)	Subtotals only
9.4.1 Childhood autism MMR	1		Rate Ratio (IV, Random, 95% CI)	0.45 [0.33, 0.62]
9.4.2 Other ASD. MMR	1		Rate Ratio (IV, Random, 95% CI)	0.55 [0.39, 0.80]
9.4.3 Definite regression. MMR	1		Rate Ratio (IV, Random, 95% CI)	0.73 [0.44, 1.20]
9.4.4 Definite + probable regression. MMR	1		Rate Ratio (IV, Random, 95% CI)	0.73 [0.46, 1.16]
9.4.5 All ASD. MMR	1		Rate Ratio (IV, Random, 95% CI)	0.49 [0.39, 0.63]