Table 6.

Summary estimates for household SHS exposure comparisons grouped by type of asthma cases [ever (1 outlier excluded) versus incident asthma].^a

Covariable influence on reference estimate of RR	Combined RRsb	95% CI
Ever asthma modelc
Joint referenced (n = 22)	1.21	1.17–1.26
Not controlled for family atopy (n = 12)	1.02	0.90–1.16
Not adjusted for child’s own smoking (n = 12)	1.63	1.54–1.73
Includes subjects < 6 years of age (n = 5)	1.45	1.39–1.52
Incident asthma modele
Joint referencef (n = 8)	1.33	1.14–1.56
Not controlled for child atopy (n = 3)	1.09	0.93–1.28
All study subjects < 6 years of age (n = 2)	1.05	0.94–1.16

RR, corrected estimate of relative risk.

^aWe report fixed-effects estimates; the log rate ratio regressed on the set of covariates listed in the table for each meta-regression.

^bRatio of corrected relative risk estimates are comparing studies/strata in the designated index category with studies/strata in the reference category of that covariate.

^cResidual homogeneity, p = 0.85.

^dEver asthma model reference category = studies that included only older children, controlled for child’s own smoking, and controlled for family atopy.

^eResidual homogeneity, p = 0.82.

^fIncident asthma model reference category = only older children and controlled for child atopy.