This thesis used data from the large-scale population-based Tromsø Study. More than 45,000 inhabitants of the municipality of Tromsø participated in at least one of the seven surveys conducted between 1974 and 2016 (Tromsø 1-7). In the papers constituting this thesis, musculoskeletal complaints (MSCs) were defined as having pain and/or stiffness in muscles and joints lasting for at least 3 months ...