Health Insurance Moderates the Waist Circumference and Cardiorespiratory Fitness Relationship in U.S. Adolescents

Background: Abdominal obesity is a cardiometabolic risk factor and shown to be related to cardiorespiratory fitness (CRF). The purpose of this study was to examine the moderating effects of health insurance (HI) on the waist circumference (WC) and CRF relationship in U.S. adolescents. Methods: Data from youths 12 to 15 years of age participating in the 2012 NHANES National Youth Fitness Survey (NNYFS) were used. Both WC (cm) and CRF (ml/kg/min) were measured by trained medical personnel with HI status assessed via questionnaire by proxy. Binary variables were created at the median for WC and CRF. Multivariate logistic regression was used to examine the relationship between WC, HI and CRF while controlling for confounding variables. Results: The overall prevalence of no HI was 6.5% (95% CI: 2.78 - 10.20). Findings from the fully adjusted model predicting low CRF showed a significant (p = .020) WC-by-HI interaction. Slicing the model by HI status showed a significant decreased risk of low CRF for adolescents with HI and low WC (OR = 0.25, 95% CI: 0.19 - 0.33). Additionally, a significant decreased risk of low CRF was seen among those with no HI and low WC (OR = 0.50, 95% CI: 0.28 - 0.88). Slicing the model by WC status showed a significant increased risk of low CRF for adolescents with low WC and no HI (OR = 2.44, 95% CI: 1.22 - 5.32). However, no significant HI and CRF relationship was observed among adolescents with high WC. Conclusion: This study showed that HI moderates the WC and CRF relationship in U.S. adolescents. Specifically, having low WC appears to protect adolescents against low CRF. Whereas having HI looks as if to protect against low CRF only for those with low WC.