e., non-traumatic, phakic) RRD. Although in Italy the age ranges for the working population are wider (at the 2001 census about find more 62,000 workers were aged 75 years or older), for the calculation of rates among Tuscan manual and non-manual workers and housewives, we restricted the study population to subjects aged 25–59 years because of limited numbers of cases in the youngest age groups and large numbers of retired subjects in the oldest age groups. We also excluded

members of the armed forces (due to the difficulty in determining whether their work was manual or non-manual); students (due to possible misclassification in the case of students with concurrent occupational exposure); cases with undeclared/unknown

employment status (due to treatment outside Tuscany); unemployed or retired subjects (due to lack of information about previous occupational status); people yet to obtain a first job; and patients with “other” (unspecified) job titles. No house husbands were reported among surgically treated cases of RRD in Tuscany. To obtain population data for the age groups of interest in the study area, including numbers of manual workers, non-manual workers and full-time housewives, we referred to the closest national census, conducted in 2001 by the National Institute of Statistics (ISTAT). Statistical analysis We calculated age- and sex-specific incidence rates (per 100,000 person-years) for manual workers, non-manual workers and housewives, and also overall rates directly standardized according to the Standard European Population proposed by the World Health Organization (Waterhouse Opaganib et al. 1976). We calculated age-specific rate ratios (RRs) for male and female manual workers and housewives, taking non-manual workers as the reference category. The likelihood ratio statistic was used to test the null hypothesis that the two rates of

interest were equal (Kirkwood and Sterne 2003). To test trends in incidence rates across five-year age bands, we used the score test and derived RR estimates for a unit increase in age class (Clayton and Hills 1993). For both rates and RRs, we calculated 95 % CI. Since the hospital discharge records database selleck compound did not permit identification of patients in years before the observation period, we carried out a sensitivity analysis in which we excluded the first 2 years of the observation period (i.e., 1997 and 1998) to explore the possibility that the main analysis might have been distorted by the inclusion of some readmissions of prevalent cases. Stata 11.2 SE (Stata Corporation, Texas, TX, USA) was used for analysis with a significance level of 0.05. Results Data on employment were available for 2,444 (89 %) of 2,753 surgically treated cases of idiopathic RRD among Tuscan residents aged 25–59 years (age exclusions: ≥60 years, n = 4,120; <25 years, n = 178).