Musculoskeletal pain is very common, may be acute or chronic, and is a major cause of morbidity and occupational sickness absence. Studies have found a prevalence of chronic musculoskeletal pain in approximately 13% of the adult Danish population,  16% of adults in the UK,  and 40% to 67% of women in New Zealand.  Over 20% of adults in Sweden report having back pain or shoulder pain.  Back pain is the second most common cause of loss of productive work time in US adults (after headache), accounting for a mean loss of over 5 hours' work time each week in those affected. Sickness absence and reduced productivity while at work caused by common pain conditions have been estimated to cost US businesses $61.2 billion per year.