Changes in ADHD symptoms according to the change in mobile phone use for voice calls and playing game over 2 years.

<p>Numbers in parentheses are the number of subjects in the corresponding group.</p

Simultaneous Model of Mobile Phone Use Variables Associated with ADHD in Children Stratified by the Blood Lead Level, 2008–2010, Korea, the CHEER study.

<p>CHEER, Children’s Health and Environmental Health Research, ADHD, Attention Deficit Hyperactivity Disorder.</p><p>Odds ratios and 95% confidence intervals estimated using the generalized estimating equation model including three mobile phone use variables and simultaneously adjusted for age, gender, number of siblings, area, household income, maternal smoking during pregnancy, child’s history of neuropsychiatric illness, and parental marital status as time-independent covariates.</p><p>p-trend calculated using the ordinal scale of the variable in the corresponding model.</p><p>The cut-off point of the high and low groups was the upper 25 percentile of the distribution of the higher levels between two blood lead levels in 2008 and 2010.</p><p>p for multiplicative interaction between blood lead level (high vs. low) and time-varying variables of mobile phone use as a continuous scale.</p>*<p>Among children who owned a mobile phone.</p

Number of children participating in the CHEER study by survey years.

<p>Of 2,516 children at baseline in 2008 and 2010 shown as the dotted lined box, 2,422 were included after excluding children with incomplete questionnaire responses on mobile phone use or a lack of blood lead measurements in 2008 and 2010.</p

Association Between Mobile Phone Use and ADHD in Children Stratified by the Blood Lead Level in 2008 and 2010, Korea, the CHEER study.

<p>CHEER, Children’s Health and Environmental Health Research, ADHD, Attention Deficit Hyperactivity Disorder.</p><p>Odds ratios and 95% confidence intervals were estimated using the generalized estimating equation model adjusted for age, gender, number of siblings, area, household income, maternal smoking during pregnancy, child’s history of neuropsychiatric illness, parental marital status, and parental history of neuropsychiatric disease as time-independent covariates.</p><p>p-trend calculated using the ordinal scale of the variable in the corresponding model.</p><p>The cut-off point of the high and low groups was the upper 25 percentile of the distribution of the higher between two blood lead levels in 2008 and 2010.</p><p>p for multiplicative interaction between blood lead level (high vs. low) and time-varying variables of mobile phone use as a continuous scale.</p>*<p>Among children who owned a mobile phone.</p

Characteristics and Mobile Phone Use Patterns of Children in 2008 to 2010, Korea, the CHEER study.

<p>CHEER, Children’s Health and Environmental Health Research, ADHD, Attention Deficit Hyperactivity Disorder. 1 USD equals approximately 1,084.5 KRW as of 8/9/2011.</p>*<p>Among children who owned a mobile phone.</p