On the other hand, employment appears to improve life outcomes, including by reducing the need for medical treatment, as well as by raising household income. While causality is complicated, the importance of drawing workers into the labour force and employment is highlighted by the relationships between non-participation and disability and drug use. Prescription rates appear to be higher where labour force participation is lower. There is also a possible relationship between drug use and disability. This may arise after the definition of disability was extended to include chronic conditions. Krueger (2017(47)) found that around one-fifth of the non-participating prime age males were also regularly taking opioid painkillers.