The study was renewed in 1993 and again in 1997 to continue the follow-up of the cohort and collect further outcome data. This was achieved by 1) continued collection of sickness absence data; 2) obtaining information from GP's regarding long spells of absence; 3) obtaining death certificates and cancer registrations; and 4) a repeat questionnaire to all 10,314 participants to ensure completeness of outcome data. With additional outcome data the investigators used their extensive exposure database to explain the socio-economic gradient in health, encompassing both external influences and biomedical mechanisms. The main focus of the analysis was the role of work stress and social supports and networks both in explaining differences in health between socio-economic groups and individual differences in health. The analysis of these individual differences in health paid particular attention to women and ethnic minorities.