Shoulder impingement syndrome in relation to shoulder intensive work

Objectives-To analyse the risk of shoulder impingement syndrome relative to shoulder intensive work. Methods-A cross sectional study of a historical cohort of 1591 workers empl oyed between 1986 and 1993 at a slaughterhouse or a chemical factory. Worke rs not doing tasks in slaughtering or meat processing constituted the refer ence group. Intensity of shoulder work in meat processing tasks was assesse d by video based observations. Information on shoulder disorders was collec ted by questionnaire and by physical examinations. Impingement syndrome was diagnosed when shoulder symptoms had been present for at least 3 months du ring the past year and there were signs of subacromial impingement in the c orresponding shoulder at physical examination. Shoulder function was assess ed at the same occasion with the Constant scoring technique. Prevalence of shoulder impingement syndrome was analysed according to job title and cumul ative exposure. Results-Prevalence ratio for shoulder impingement syndrome was 5.27 (95% co nfidence interval (95% Cl), 2.09 to 12.26) among currently working and 7.90 (95% Cl, 2.94 to 21.18) among former slaughterhouse workers. Transformed m odel based prevalence ratios according to years in slaughterhouse work show ed an overall association between cumulative exposure and risk for shoulder impingement syndrome. Conclusions-This study supports the hypothesis that shoulder intensive work is a risk factor for impingement syndrome of the shoulder. Despite the his torical cohort design healthy worker selection may have influenced the expo sure-response relation found.