Heterogeneity and event dependence in the analysis of sickness absence
- Equal contributors
1 Department of Experimental and Health Sciences, Center for Research in Occupational Health (CiSAL), Universitat Pompeu Fabra (UPF), C/Doctor Aiguader 88, Barcelona 08003, Spain
2 CIBER in Epidemiology and Public Health, Barcelona, Spain
3 Southwest Center for Occupational and Environmental Health, Division of Epidemiology, Human Genetics and Environmental Sciences, The University of Texas School of Public Health, San Antonio Campus, San Antonio, TX, USA
4 Southwest Center for Occupational and Environmental Health, Division of Epidemiology, Human Genetics and Environmental Sciences, The University of Texas School of Public Health, Houston Campus, Houston, TX, USA
5 Institut Català d’Avaluacions Mèdiques i Sanitàries (ICAMS), Departament de Salut, Generalitat de Catalunya, Barcelona, Spain
6 Department of Public Health Sciences, School of Public Health, University of Alberta, Edmonton, AB, Canada
BMC Medical Research Methodology 2013, 13:114 doi:10.1186/1471-2288-13-114Published: 16 September 2013
Sickness absence (SA) is an important social, economic and public health issue. Identifying and understanding the determinants, whether biological, regulatory or, health services-related, of variability in SA duration is essential for better management of SA. The conditional frailty model (CFM) is useful when repeated SA events occur within the same individual, as it allows simultaneous analysis of event dependence and heterogeneity due to unknown, unmeasured, or unmeasurable factors. However, its use may encounter computational limitations when applied to very large data sets, as may frequently occur in the analysis of SA duration.
To overcome the computational issue, we propose a Poisson-based conditional frailty model (CFPM) for repeated SA events that accounts for both event dependence and heterogeneity. To demonstrate the usefulness of the model proposed in the SA duration context, we used data from all non-work-related SA episodes that occurred in Catalonia (Spain) in 2007, initiated by either a diagnosis of neoplasm or mental and behavioral disorders.
As expected, the CFPM results were very similar to those of the CFM for both diagnosis groups. The CPU time for the CFPM was substantially shorter than the CFM.
The CFPM is an suitable alternative to the CFM in survival analysis with recurrent events, especially with large databases.