Table 4.

Odds Ratios for the Association Between Postnatal Cell Phone Exposure and Hearing Loss in Children at Age 7 Years (According to Mothers' Reports)

Year of Child’s Birth	Unadjusted	Adjusted, traditional outcome regression modela	Adjusted, marginal structural model with IPWa	Adjusted, doubly robust estimation modelb
1997 (n=24)	--c	--c	--c	--c
1998 (n=6,779)	1.12 [0.75–1.68]	1.18 [0.61–2.26]	1.34 [0.70–2.54]	1.32 [0.68–2.55]
1999 (n=11,298)	1.29 [0.96–1.74]	1.18 [0.78–1.77]	1.17 [0.78–1.77]	1.17 [0.78–1.77]
2000 (n=13,131)	1.33 [1.00–1.76]	1.46 [1.01–2.11]	1.48 [1.02–2.15]	1.48 [1.02–2.15]
2001 (n=11,319)	1.08 [0.79–1.48]	0.79 [0.49–1.28]	0.80 [0.49–1.30]	0.79 [0.48–1.29]
2002 (n=9,136)	1.39 [1.00–1.92]	1.32 [0.86–2.00]	1.34 [0.88–2.03]	1.33 [0.87–2.03]
2003 (n=993)	0.85 [0.27–2.70]	5.17 [0.52–51.41]	3.43 [0.37–32.20]	--c
Combined (n=52,680)	1.23 [1.07–1.41]	1.21 [0.99–1.46]	1.23 [1.01–1.49]	1.22 [1.00–1.49]

^aAdjustment model or IPW included mother's cell phone use during pregnancy, alcohol use during pregnancy, smoking during pregnancy, fever during pregnancy, mother's age, social-occupational status, breast feeding, ear infection by age 18 months, sex of child, and gestational age at birth, and reduced hearing at age 18 months.

^bDoubly robust estimation combining covariate adjustment in the traditional outcome regression with IPW application in a marginal structural model using adjustment scheme.

^cInsufficient sample size