According to the Milken Institute (using 2003 NCS-R data), Americans took roughly 3.6 billion days off within a two-year span due to health-related reasons, leading to an estimated $127 billion loss. Vuong, Wei, and Beverly (2015) focus on how functional limitations due to chronic diseases relate to the loss of workdays and economic income. Notably, many people with chronic illnesses do not experience impediments to their daily activities; such functional limitations vary based on the type and severity of the condition, along with other personal factors.