Study population

National Health and Nutrition Examination Surveys (NHANES) from the 2011-2012, 2013-2014, and 2015 to 2016 (Total n = 29,902) cycles were used for this analysis. More than half of the participants were children and adolescents (n=9,956). NHANES is a cross-sectional, publicly accessible and continuous survey conducted in a 2-year cycle by the National Center for Health Statistics (NCHS) of the Centers for Disease Control and Prevention (CDC) to monitor health and nutrition status of the US population.¹⁵ For each survey cycle, a complex 3-step weighting method is created to represent the US noninstitutional, civilian population.

The dietary data from the NHANES is obtained through 24-hour food recalls which asks detailed information about all food and beverage intake of respondents in the past 24 hours using USDA's dietary data collection instrument (http://www.ars.usda.gov/nea/bhnrc/fsrg). Children aged 12 years and above completed the survey on their own. Proxy respondents reported for children <5 years. Proxy-assisted interview are conducted among children 5-to-11 years old. In the 2011-2016 cycle, two nonconsecutive 24-hour recall questionnaires were administered on two separate days to the same respondent in order to establish the dietary pattern of each individual.¹⁶ The reliability of two non-consecutive 24-hour dietary recalls was assessed using dietary recall status variables provided by NHANES: DR1DRSTZ variable for the Day 1 interview and DR2DRSTZ variable for the Day 2 interview. Non-reliable responses that did not complete the first 4 steps of the 5-step data collection instrument or did not identify eating occasion were excluded in the final analysis (n = 18).

Hence, the final analytical sample included children aged 2- to 17- year old who completed two 24-hour recalls with reliable responses (n = 9,938). We included 3,888 (37.5%, 95% confidence interval [CI] 35.5-39.6%) participants who had no sugar-sweetened beverage (SSB) consumption (0 kcal/day) in two 24-hour recalls; and 4,968 (51.0%, 95% CI 48.9-52.8%) moderate drinkers (defined as 1-499 kcal/day in SSB consumption). Heavy SSB drinkers, defined as consumption of ≥ 500 kcal/day in SSB in any two 24-hour recalls were the primary independent variable of interest and comprised 1082 (11.5%, 95% CI 10.6-12.5%) children in this sample. The primary dependent variable was self-reported current asthma diagnosis (yes or no).