Risk of surgery for subacromial impingement syndrome in relation to neck-shoulder complaints and occupational biomechanical exposures: a longitudinal study

Objectives The aim of this longitudinal study was to evaluate the risk of surgery for subacromial impingement syndrome (SIS) in relation to neck-shoulder complaints and occupational biomechanical shoulder exposures. Methods The study was based on the Musculoskeletal Research Database at the Danish Ramazzini Centre. We linked baseline questionnaire information from 1993-2004 on neck-shoulder complaints, job titles, psychosocial work factors, body mass index, and smoking with register information on first-time surgery for SIS from 1996-2008. Biomechanical exposure measures were obtained from a job exposure matrix based on expert judgment. We applied multivariable Cox regression. Results During 280 125 person-years of follow-up among 37 402 persons, 557 first-time operations for SIS occurred. Crude surgery rates increased from 1.1 to 2.5 per 1000 person-years with increasing shoulder load. Using no neck-shoulder complaints and low shoulder load at baseline as a reference, no neck-shoulder complaints and high shoulder load showed an adjusted hazard ratio (HRadj) of 2.55 [95% confidence interval (95% CI) 1.59-4.09], while neck-shoulder complaints in combination with high shoulder load showed an HRadj of 4.52 (95% CI 2.87-7.13). Subanalyses based on 18 856 persons showed an HRadj of 5.40 (95% CI 2.88-10.11) for complaints located specifically in the shoulder in combination with high shoulder load. Conclusions Based on these findings, persons with neck-shoulder and especially shoulder complaints in combination with high shoulder load seem an obvious target group for interventions aimed at reducing exposures to prevent surgery for SIS.