*2.1. Study Design*

We obtained data from the 2013–2014 National Health and Nutrition Examination Survey (NHANES). NHNAES is a nationally representative cross-sectional survey conducted by the National Center for Health Statistics (NCHS) and Centers for Disease Control and Prevention. NHANES includes information about the non-institutionalised US population. This database is used worldwide and has produced satisfactory results [6,7].
