Understanding population trends and process (UPTAP): Inaugural Conference

30 March 2006

Claudia Thomas

Centre for Paediatric Epidemiology & Biostatistics

Institute of Child Health

University College London

Mid-Career fellowship

•Start date: May 2007

•Duration: 2 years

•Supervisor:

Professor Chris Power (ICH)

•Collaborators:

Professor Heather Joshi, Centre for Longitudinal Studies, Institute of Education, London

Professor Stephen Stansfeld, Queen Mary’s School of Medicine and Dentistry, London

How does employment affect cardiovascular risk? A life-course approach in the 1958 cohort

AIM

To understand the role of labour market participation as a process that leads to social inequalities in cardiovascular disease.

Background: employment and health

Structure and organisation of paid employment has adverse consequences for various health outcomes:

•Lack of job security associated with poor self-reported health, chronic disease and psychological distress (Whitehall II).

(Virtanen et al. JECH, 2002, 56:569; Ferrie et al. BMJ, 2001, 322:647; Ferrie et al. BMJ, 1995, 311:1264)

•Unemployment related to mortality and psychological distress

(Thomas et al. JECH 2005, 59:243; Pensola et al. Soc Sci Med, 2004, 58:2149; Murphy & Athanasou, J Occ Org Psych, 1999, 72:83)

•Combination of work and motherhood (“role overload”) has adverse consequences for health.

(Weatherall et al. Soc Sci Med, 1994, 38:285)

Background: employment and CVD

Most studies have looked at psycho-social affects of work on

cardiovascular disease:

•Job strain, job demands, decision latitude

(Agardh et al. Diabetes Care, 2003, 26:719; Kuper et al. JECH, 2003, 57:147)

Less is known about aspects of employment on cardiovascular

disease:

•Evidence for relationship with lower socio-economic position

(Lawlor et al. Am J Pub Hlth, 2005, 95:91; Feldman & Steptoe, Hlth Psych, 2003, 22:398)

•Relationship with shift-work

(Knutsson & Boggild, Rev Environ Hlth, 2000, 15:359; Boggild & Knutsson, Scand J Work &

Environ Hlth, 1999, 25:85)

Objectives

•To study the direct relationships between employment characteristics and adult cardiovascular risk markers.

•To study the indirect pathways: diet, physical activity, weight gain.

•Take into account social processes occurring earlier in life, such as education, that determine how individuals arrive in their occupational destinations.

•Understand how the more complex patterns of labour market participation experienced by women, such as, the combined roles of work and motherhood, are related to cardiovascular disease.

Methods

•Dataset: 1958 British birth cohort

•Outcomes: cardiovascular markers measured at age 45 years (BP, HbA1c, triglycerides, cholesterol, waist/hip circumference, BMI)

•Main exposures: employment information back to age 16y

•Mediators: health behaviours in adulthood (smoking, alcohol, diet, physical activity); adiposity throughout the lifecourse

•Other covariates/confounders: SEP in childhood and adulthood, early environment (birth weight, health in childhood/adolescence) home circumstances in adulthood, education, region of residence.

Methods: Analyses

1. Direct relationship between labour market participation and cardiovascular measures:

• Cross-sectional and longitudinal associations• Whether observed associations are explained by earlier life factors

(neonatal circumstances, education, childhood health, parents SEP)

2. Indirect associations between labour market participation and cardiovascular measures

• Mediators: weight change, health behaviours

3. Statistical methods: linear and logistic regression; multilevel modelling; structural equations (pathway analysis)

1958 British birth cohort (NCDS)

Perinatal Mortality Survey

• All live births one week in March 1958• England, Scotland and Wales• ~17000

Followed up: • age 7y (1965)• 11y (1969)• 16y (1974)• 23y (1981)• 33y (1991)• 42y (2000)• 45y (2003) – biomedical survey

1958 cohort biomedical survey

•At age 45 years

•MRC “Health of the Public” grant (Prof C Power, Prof D Strachan)

•Nurse interviews

• Physical measurements, e.g. height, weight, BP• Blood collection• Nurse administered questionnaire (CAPI)• Self completed CAPI section: sensitive information

1958 cohort biomedical sample

6489 cases not in biomedical sample:1196 ineligible - dead

1236 ineligible - living outside GB1041 permanent refusals

31 NCDS6 proxy respondents2985 not issued for other reasons

17638eligible cases in March 1958

9377 productive cases

(includes 29 dress rehearsal

cases, 9 ‘lost productives’ with no

CAPI data)

12069biomedical issued

sample(includes 31 dress rehearsal cases)

18558“total cohort”

sample

920 immigrants

added NCDS1-NCDS3

93 ineligible cases (28 dead, 65 living outside GB)

1804 refusals(includes 1 case whose data was

withdrawn after interview)697 non-contacts

98 other unproductives

Liz Fuller, 2006

1958 cohort: employment patterns

Historical context

•Cohort entered labour market in mid-1970s to early 1980s

•Unemployment had started to rise, subsequent periods of boom and recession

•Women’s participation had also increased: part-time, low level and low-paying jobs

•During cohort member’s working lives, reorganisation and restructuring of work: eg increased computer use

1958 cohort: economic activity

33y (1991) 42y (2000)

Men (%)

Women (%)

Men (%)

Women (%)

Economically active 96 70 93 80

Paid employment 90 68 91 78

Full-time - 37 - 44

Part-time - 32 - 34

Unemployed 6 2 3 2

Economically inactive 2 29 5 18

N 5583 5786 5604 5778

Source: Changing Britain, Changing Lives. E. Ferri, J. Bynner, M. Wadsworth, 2003

1958 cohort: employment characteristics

•Occupation

•Grade (Registrar general)

•Hours of work

•At 33y, 50% of male employees compared to 11% of female employees worked more than 40 hours per week

•Night work done more frequently by men than women

•Paid versus self-employment

•Approximately 14% self-employed (more men than women)

1958 cohort: work and healthKey publications on labour participation and health in the cohort to date:

Llena-Nozal et al. The effect of work on mental health: does occupation matter? Health Economics, 2004, 13: 1045-1062

Power et al. Childhood and adulthood risk factors for socio-economic differentials in psychological distress: evidence from the 1958 British birth cohort. Social Science & Medicine, 2002, 55: 1989-2004

Matthews & Power. Socio-economic gradients in psychological distress: a focus on women, social roles and work-home characteristics. Social Science & Medicine, 2002, 54: 799-810

Matthews et al. Gender, work roles and psychosocial work characteristics as determinants of health. Social Science & Medicine, 1998, 46: 1417-1424

Montgomery et al. Health and social precursors of unemployment in young men in Great Britain. JECH, 1996, 50: 415-422

Joshi, et al. Employment after childbearing and women’s subsequent labour force participation: Evidence from the 1958 birth cohort. J Population Economics, 1996, 9:325-348

Acknowledgements

ESRC UPTAP secondary data analysis initiative for provision of Mid-Career Fellowship

MRC funding of biomedical survey

Centre for Longitudinal Studies: management of the1958 cohort; co-ordination of follow-up surveys; data collection and provision of data.