Design and sample
The WORKss Cohort Platform 7, a retrospective cohort, includes affiliates registered with Social Security who are part of the CWLS and who have been employed or unemployed receiving a benefit or subsidy at least one day between 2004 and 2015 in the General Social Security Regime. Members of Special Regime and pensioners who have not been active at any time in the General Regime between 2004 and 2015 have been excluded.
Likewise, in order to control the possible cohort or generation effect, only people born between 1950 and 1979 have been included and were grouped into three birth cohorts: 1950-1959 (between 45 and 54 years in 2004), 1960-1969 (between 35 and 44 years in 2004) and 1970-1979 (between 25 and 34 years in 2004).
Figure 2. Scheme summarizing the monitoring of the study population between 2004 and 2015 organized in three cohorts of members of the general social security regime in Spain according to their age in 2004 (25-34 years (early), 35-44 years (middle) and 45-54 years (late).
The total number of people on which the information presented on the platform is based is 753,341 members.
Health indicators and descriptive variables
In this project, the two health indicators included in the CWLS are permanent disability and premature mortality.
Permanent disability, according to the General Law of Social Security, includes those affiliates to whom, after having suffered a health problem, and before the age of their retirement, are verified by a medical commission (Disability Assessment Teams in each province and Institut Català d’Avaluacions Mèdiques in Catalonia) that due to their health problem their ability to work is reduced or completely suspended. This study includes those permanent disabilities for common and work-related medical conditions leading to a total, absolute, and high degree of disability between 2004 and 2015, which represents a total of 18,288 cases, excluding partial permanent disability.
On the other hand, premature mortality includes all people who died before age 65 while they were affiliated with the Social Security system between 2004 and 2015. The total number of deaths between 2004 and 2015 was 5661, with a median of 50 years.
For each person included in the study there is information about occupation, classified as non-manual qualified and non-qualified, and manual qualified and non-qualified (Figure 3); and economic activity, coded according to the Spanish National Classification of Economic Activities (CNAE) 2009, and grouped into ten categories: Agriculture, livestock, fishing and extractive industries; Manufacturing industry; Energy production and distribution; Building; Commerce; Hospitality, transportation and telecommunications; Financial intermediation; Real estate activities; Public administration; Education, health activities, community services, and household activities.
Since individuals could change their occupation and/or the economic activity of their company throughout the follow-up period, we annually assign each individual to the category they spent most of the time in that year.
Figure 3. Professional category correspondence according to the Social Security contribution group 9.
Analysis and global results
First, the annual incidence rates of permanent disability and premature mortality are calculated as a ratio between the number of permanent disability and premature mortality cases in a specific year and the exact time accumulated by each member in that year. That is, we add the exact time in which each person was registered in the general Social Security regime that year. In cases of permanent disability or premature mortality, time has been subtracted from the date on which death or disability occurred.
The rate, of both permanent disability and premature mortality, has been expressed per 10,000 affiliates-year and calculated specifically according to the possible combinations of occupation (4 categories), economic activity (10 categories), and birth cohort (3 categories), for men and women separately.
As a summary of the graphs that can be seen in the WORKss Cohort Platform, Table 1 shows the incidence rates per 10,000 person-year of permanent disability and premature mortality per birth cohort according to sex, occupation, and economic activity.
Table 1a. Permanent disability (incidence rate per 10,000 person-year) in the 2004-2015 period by birth cohort according to sex, occupation and economic activity.
Table 1b. Premature mortality (incidence rate per 10,000 person-year) in the 2004-2015 period by birth cohort according to sex, occupation and economic activity.