In 1996, the Washington State Department of Health (DOH) conducted its first statewide survey to help monitor the trends of dental disease in children. In 2000, as part of the second statewide survey, Public Health –Seattle & King County (Public Health) conducted its first random sample survey of 2nd and 3rd grade students throughout King County. In 2005, Public Health participated in the third Smile Survey, conducting a county wide random survey of 2nd and 3rd grade students, along with a random survey specific to Seattle students. In addition to the elementary school surveys in 2005, DOH also surveyed children in Head Start and Early Childhood and Education Assistance Program (ECEAP). Public Health conducted a random sample of preschool sites throughout the county.
Sites for the King County and Seattle samples were selected using methods used for the statewide Smile Survey. The following excerpt is taken from the Methods section in the state Smile Survey report:
An electronic data file of all elementary schools in Washington was obtained from the Office of Superintendent of Public Instruction (OSPI). The data file, which was for the 2003-2004 school year, contained the following information for each school – district, county, total enrollment, 2nd and 3rd grade enrollment, and percent of children participating in the free or reduced lunch program. All schools with at least 25 children in second and/or third grade were included in the sampling frame (1,059 schools and 142,504 students) Implicit stratification by percent of children eligible for the free or reduced price lunch (FRL) program was used to select a probability sample of 67 schools. Selecting a sample using implicit stratification assures that the sample is representative of the state’s schools in terms of free/reduced lunch participation. If a school refused to participate, a replacement school within the same sampling strata was randomly selected. If the sample school plus two replacement schools refused to participate, no data were collected in that sampling stratum. Of the 67 stratums, data is available for 66.
Data entry and analysis was completed using EPI INFO Version 3.2.2. EPI INFO is a public access software program developed and supported by the Centers for Disease Control and Prevention. The data were adjusted for non-response within each school. For the non-responsive sampling weight, the number of children enrolled in each school was divided by the number of children screened. Unless otherwise noted, all of the data presented in this report have been adjusted for non-response (EPI INFO Complex Sampling, weight variable = weight, primary sampling unit = school name.)
The elementary school sample of the King County survey included 19 schools with 1758 children participating, for a response rate of 80%. A random sample specific to Seattle was also selected which included 13 schools with 1022 children participating for a response rate of 77%. The Seattle sample included some schools also drawn for the King County sample.
Sites had the option of participating with positive consent, or passive consent. Positive consent is where parents sign their children up to participate, whereas passive consent is when children are screened unless parents indicate otherwise. Sites that were also participating in a dental sealant program by Public Health used positive consent for 2nd grade students and passive consent for 3rd grade students. The same survey information and criteria were used regardless of the type of consent. Calibrated dental professionals using gloves, a penlight and a dental mirror conducted screenings on site. This type of dental screening underreports dental disease.
Demographic variables included gender, race/ethnicity, language spoken at home, and for elementary students, eligibility for free and/or reduced price lunch program (FRL) as a proxy for overall socioeconomic status. Oral health indicators included untreated caries (decay), treated caries, rampant caries (decay on seven or more teeth), dental sealants and treatment urgency. Data was entered and analyzed using the EPI-INFO program from the Centers for Disease Control and Prevention (CDC). Detailed information on methodology is available in the state report, Smile Survey 2005: The Oral Health of Washington’s Children, on the web at www.doh.wa.gov/cfh/Oral_Health.
