. 2018 Jun 11;146(12):1584–1592. doi: 10.1017/S0950268818001474

Table 2.

Mediation analysis of fever in the association between age at first vaccination or type of vaccine and antibody concentration

			CDE^a	95% CI	NDE^b	95% CI	NIE	95% CI	TE	95% CI	NIE/TE^c (%)
Effect of age on antibody concentration (with age × fever interaction)^d
Age (months) (ref = 12)	11	Log₁₀MC diff	−0.14	−0.20 to −0.09	−0.07	−0.12 to −0.02	−0.06	−0.08 to −0.03	−0.13	−0.18 to −0.07	44.5
	11	GMC ratio	0.72	0.63–0.81	0.85	0.76–0.95	0.88	0.83, 0.93	0.75	0.66–0.84
	13–14	Log₁₀MC diff	0.08	0.05–0.11	0.08	0.05–0.11	0.002	−0.01 to 0.01	0.09	0.05–0.12	2.0
	13–14	GMC ratio	1.21	1.13–1.30	1.21	1.13–1.30	1.00	0.99, 1.02	1.22	1.13–1.31
	15–22	Log₁₀MC diff	0.16	0.12–0.19	0.14	0.11–0.17	0.003	−0.003 to 0.01	0.14	0.11–0.18	2.3
	15–22	GMC ratio	1.44	1.32–1.57	1.38	1.28–1.48	1.01	0.99, 1.02	1.39	1.29–1.50
Effect of age on antibody concentration (without age × fever interaction)^d^,^e
Age (months) (ref = 12)	11	Log₁₀MC diff	−0.08	−0.13 to −0.03			−0.03	−0.04 to −0.02	−0.11	−0.16 to −0.06	26.5
	11	GMC ratio	0.83	0.74–0.93			0.93	0.91, 0.96	0.78	0.69–0.87
	13–14	Log₁₀MC diff	0.08	0.05–0.11			0.002	−0.01 to 0.01	0.09	0.05–0.12	2.0
	13–14	GMC ratio	1.21	1.13–1.30			1.00	0.99, 1.02	1.22	1.13–1.31
	15–22	Log₁₀MC diff	0.14	0.11–0.17			0.004	−0.004 to 0.01	0.14	0.11–0.17	2.9
	15–22	GMC ratio	1.37	1.27–1.48			1.01	0.99, 1.03	1.38	1.28–1.49
Effect of type of vaccine on antibody concentration^e^,^f
Type of vaccine (ref = MMR)	MMRV	Log₁₀MC diff	0.17	0.14–0.20			0.04	0.03–0.04	0.21	0.18–0.24	17.6
Type of vaccine (ref = MMR)	MMRV	GMC ratio	1.48	1.39–1.58			1.09	1.07–1.11	1.61	1.51–1.72

CDE, Controlled direct effect; CI, confidence intervals; GMC, geometric mean concentrations; Log₁₀MC diff, difference of log base 10 mean concentrations; MMR, Measles-Mumps-Rubella vaccine; MMRV, Measles-Mumps-Rubella-Varicella vaccine; NDE, natural direct effect; NIE, natural indirect effect; TE, total effect; Ref, reference category.

CDE for fever set at temperature <38 °C.

NDE for covariates set at their average level.

Percentage of the total effect mediated by fever = NIE/TE × 100.

Models adjusted for type of vaccine, study and country.

For models without interaction term CDE = NDE.

Models adjusted for age at first vaccination, study and country.