Development and evaluation of a brief calcium assessment tool for adolescents

Abstract

Adolescence is a critical time to achieve peak bone mass. However, results of national surveys suggest that young people are not consuming adequate amounts of calcium. A simple calcium self-assessment tool with low respondent burden could provide immediate feedback that may encourage calcium consumption. This study used data reduction methods to shorten a previously evaluated calcium-specific food frequency questionnaire to the 15-item Brief Calcium Assessment Tool (BCAT). Sample 1 was a cross-sectional sample of 1,426 students in sixth and 11th grades (April 2002 to February 2003) who completed the calcium food frequency questionnaire. Sample 1 was divided into two matching samples (Group 1 and Group 2). Sample 2 was a cross-sectional sample of 745 girls in sixth grade that completed the calcium food frequency questionnaire (July 2002 to February 2005). The development of the BCAT and its calcium score used two unique samples (Group 1 of Sample 1 and Sample 2) followed by confirmation of the score in a second sample (Group 2 of Sample 1). Bone mineral content was measured among the girls in Sample 2. The BCAT calcium score was associated with total hip bone mineral content (beta=.014, P=0.003) and femoral neck bone mineral content (beta=.002, P=0.006) while adjusting for covariates. Sample 3 (n=265), a subsample of Sample 2, completed bone measures 12 months later. The BCAT calcium score at the baseline was a predictor of total body bone mineral content (beta=.279, P=0.041) at 12 months. The correlation of BCAT scores 1 week apart was .76 (P<0.001) among a convenience sample of 41 boys and girls aged 9 to 17 years (October 2005 to December 2005). The BCAT took about 5 minutes to complete. The significant relationship between bone mass and the BCAT calcium score supports the use of BCAT as a tool to assess food calcium intake among adolescents, especially Asian, Hispanic, and non-Hispanic white girls. The reliability and low respondent burden of the BCAT make the tool useful for large-scale studies and community-based programs.