Objective Multi-site musculoskeletal pain at multiple sites is more common than single-site pain. We investigated the developmental paths of multi-site musculoskeletal pain and the effect of work-related physical and psychosocial working conditions among blue- and white-collar workers.

Methods The study was conducted among food industry workers (N = 873) and collected in two years intervals starting from 2003 until 2009. The information on self-perceived musculoskeletal pain during preceding week, work related physical and psychosocial working conditions and various individual factors was obtained through a structured questionnaire distributed to workers. Latent class growth modelling and multinomial logistic regression were used.

Results A five-group multi-site musculoskeletal pain trajectory model (no pain stable 35.6%, stable multi-site pain 28.8%, no pain to increasing pain sites 8.8%, L-shaped 11.5% and slow increasing multi-site pain 15.3%) was identified. In a multivariate model physical strain (OR 3.34, 95% CI: 2.12–6.27), environmental factors (3.37, 1.94–5.86), repetitive movements (2.13, 1.09–4.16) awkward posture (2.26, 1.13–4.52) and mental strain (3.85, 2.25–6.57) significantly predicted stable multi-site pain trajectory. These factors also predicted slow increasing multi-site pain trajectory in a more or less in a same fashion. The associations were more prominent among blue-collar workers than their white-collar counterparts.

Conclusions A substantial proportion of individual seems to have multi-site pain persistently. Most of the physical working conditions predict the development of multi-site musculoskeletal pain.