Objectives In the current context of increasing population ageing and after trends of labour market flexibilisation, this study analyses the impact of labour trajectories on the potential years of working life lost (PYWLL) due to non-work related permanent disability (PD).

Methods Retrospective cohort of 14,999 workers affiliated with the Social Security System in Spain that began a non-work related PD between 2004 and 2010. The PYWLL is defined as the time in years between the age at which a worker initiates a PD and the official retirement age (65 years) or the age of reinstatement to a job. Two indexes of labour trajectory were obtained by Principal Components Analysis: Index 1 (number of contracts, number of unemployment periods and number of periods without affiliation) and Index 2 (percentage of inactive time). Median differences in PYWLL (MD) and 95% confidence intervals (CI95%) were computed using a median regression. The main independent variable was obtained combining tertiles (low, medium, high) of index 1 and 2 ((Index 1, Index 2): (high, high), (high, low), [3DOTS], (low, low)) with category (low, low) as reference. Analysis were stratified by gender and adjusted by the total time elapsed by each worker in the labour trajectory.

Results The median PYWLL was 8.7 for men and 11.0 for women. The greatest crude MD was for category (high, high) for men (MD:4.70, CI95%:3.88, 5.52) and (medium, high) for women (MD:4.09, CI95%:2.93, 5.25). The greatest adjusted difference in medians was for category (high, high) in men (MD:3.05, CI95%:2.64, 3.47) and in women (MD:3.68, CI95%:2.57, 4.68).

Conclusion Workers with a labour trajectory corresponding to the highest indexes have the greatest loss of PYWLL due to non-work related PD. Greater labour market flexibilisation could mean a major loss of working years and therefore an advancement of age of disability in the coming years.