Data were obtained from the North West Adelaide Health Study (NWAHS). In stage one (2000-2003), participants over the age of 18 years were randomly selected using the electronic white pages telephone directory, interviewed and invited to attend a clinic for physical assessment. In stage two (2004-2006), participants were re-contacted, invited to complete telephone interview, complete a self-administered questionnaire and have a clinical assessment. Overall, 3 206 (81% of those recruited) participants returned to the clinic during the second stage (2004-2006) which specifically focused on the collection of information relating to musculoskeletal conditions [19].