Material and Methods

1. Early RTW, but low Work Participation Methods in measuring Return to work - definingReturn to work and measuring relapses K.Biering, T. Lund, N.H. Hjøllund. Department of Occupational Medicine, Herning Regional Hospital, Demark • Background • Return to Work (RTW) is a commonly used term, but with various definitions. It can be based on self report or register data, and measure either a cross sectional proportion or a time-to-event measure. If these measures are comparable is unknown. • Different lengths of RTW-spells in register based measures has been used to define RTW, but it is unknown what is appropriate. • Previous reviews have highlighted the need to combine various measures of RTW in order to capture relapses of new sick leave episodes. • Purposes: • To compare different RTW measures in a period of 12 months and define possible measures of safe RTW and of work participation using administrative data. • To examine possible predictors of recurrent sick leave after first RTW. Material and Methods 1003 patients who were in the workforce from a cohort of 1585 PCI (percutanous coronary intervention) treated were followed in a public register of social transfer incomes Return to work was defined in 3 different ways: 1: Dichotomous at 6 and 12 months 2: Time to first spell of 1 or 4 weeks self-support 12 months after the PCI 3: “Work Participation Score”, defined as a fraction with number of self supported weeks in the numerator and number of weeks receiving social transfer payments + number of self supported weeks in the denominator. The “Work Participation Score” was dichotomised at tree points (25%, 50% and 75%) for comparison with the other measures. Censoring in all measures: early retirement (health-related or voluntarily) and normal retirement due to age. Agreement between measures were compared to each other using Cohen’s kappa. Associations with gender were compared using the different outcome measures in logistic regression. Finally a time to event analysis within the 781 patients, who experienced RTW during the first year, using recurrences of sick-leave within the following 12 month as event. Comparison of traditional time to first RTW with Work Participation Score • Take home messages: • Different RTW definitions show similar results • Using 4 week spells of self support is more precise than just 1 week in register data. • Traditional measures tend to overlook relapses; we suggest a “Work Participation Score” or to measure events of relapse. Results Agreement between methods evaluated with Cohen’s kappa showed good to excellent agreement. Associations with the well-known predictor (gender) were stable within methods. Safe return to work: Defining RTW as 1 week of self support compared to 4 weeks, classified 56 (5.6%) patients differently, mainly due to administrative breaks in the payments. In the group of 781 patients who experienced RTW during the first year, 163 patients(20.8%) had one ore more relapses of sick leave the following 12 months. This group would not be identified in traditional Time to event analysis of RTW. Work Participation Score adds information on recurrent sick leaves, but is not normally distributed. Predictors of relapse of sick leave were female gender, acute indication of PCI and low initial score of General Health (SF-12) Contact: Karin Biering karbie@rm.dk Life-after-heartdisease.dk