The illness flexibility model and sickness absence

Sammanfattning: Research on sickness absence has repeatedly been described as theoretically undeveloped. In this thesis the model of illness flexibility is introduced. In this model, sickness absence is assumed to be caused by people’s ability and motivation to work. Ability and motivation will in turn be affected by conditions met in and outside work. In the model, five basic components are discerned describing such conditions. Adjustment latitude describes opportunities to adjust work to health by e.g. choosing among work tasks. Attendance requirements describe negative consequences of being absent that may make a person attend work despite illness. Absence requirements are negative consequences by attending work as signals of not being wanted at work. Attendance incentives are positive consequences of attending work as stimulating work. Absence incentives are positive consequences of being absent as caring for relatives. The overall aim in the thesis is to test predictions from the illness flexibility model on sickness absence and sickness attendance. In Paper I adjustment latitude and attendance requirements were studied in relation to sickness absence and sickness attendance. In a cross-sectional design data based on self-reports from a questionnaire from inhabitants in the county of Stockholm were analysed. Low adjustment latitude, as predicted, increased women’s sickness absence. However it did not show any relation to men’s sickness absence and men’s and women’s sickness attendance. Attendance requirements were strongly associated to both men’s and women’s sickness absence and sickness attendance in the predicted way. In paper II the aim was to study whether return to work (RTW) after long-term sickness absence is affected by adjustment latitude, and whether this effect differed between those returning full-time and those returning part-time. A questionnaire was sent to salaried employees who had been on sick-leave for at least 90 days in 2000. The year after they received a questionnaire. For both men and women the likelihood to RTW increased, both among those returning part-time and full-time, with increasing number of opportunities to adjust. In paper III some components from the illness flexibility model was studied in relation to sickness absence on longitudinal data. In spring 2004 and in spring 2005 a random sample aged between 25 an 50 years from the Swedish population received questionnaires. The results showed that an intermediate level of adjustment latitude, compared to a high, was associated with an increased likelihood of being absent sick for between 1-6 days and 7 days or more. Work with little stimulation was associated with an increased likelihood of being absent sick for 7 days or more. Low or intermediate scores on attendance requirements on work were associated with an increased likelihood of being absent 7 days or more. Financial attendance requirements and demanding home tasks were not associated with the likelihood of being absent sick. In paper IV the social gradient in sickness absence was studied in relation to some components from the illness flexibility model. The sample is part of a panel originating from 1994 of inhabitants of Stockholm County which received a questionnaire 1994, 1998 and 2002. Only 2002 data was analysed. The social difference found in sickness absence 31 days or more a year decreased by 78% for women and 67% for men by adding characteristics from the illness flexibility model and health. In conclusion, the model of illness flexibility appears promising in increasing our understanding of sickness absence. Future studies should be directed to theoretical and methodological development of the components as well as future testing of predictions from the model. Such testing should be done with improved design and data as longitudinal design, register-based data of sickness absence, and tested measurements of the components of the illness flexibility model. Testing of the model should also be directed to different actions taken when ill as the inception of sickness absence, length of absence, RTW, and exclusion from the labour market.