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Background
The data to be used by the present study were collected over a two
year period from 1996-1998 under Phase 1 of the Health Variations
Programme. In total, 294 subjects were interviewed. Full lifetime
family, residential, occupational and smoking histories were collected.
Hazard exposure scores (i.e. years of exposure) were calculated
for: air pollution; residential damp; occupational fumes and dusts;
physically arduous labour; lack of job autonomy; inadequate nutrition
in childhood and adulthood; and cigarette smoking. Additionally,
a range of non-invasive physical measures including height, weight,
blood pressure and lung function were carried out.
These subjects,
as children, had taken part in Sir John Boyd Orr's survey of diet
and health between 1937-39, when a full physical examination was
conducted and household structure, diet and living conditions were
recorded. The combination of independent data on childhood together
with the full working and residential histories of the interviewees
and the objective health measures taken, provided a unique source
of comprehensive lifecourse information.
Aims and
Objectives
The present study aims to extend the use of the Phase 1 data by
answering questions which were not included in the earlier study.
It is intended to contribute to the understanding of the influence
of the workplace on health by examining the relationship between:
- workplace
and non-workplace factors;
- and workplace
physico-chemical and workplace psycho-social factors.
Additionally,
these relationships will be examined for a variety of measures of
occupation (e.g. most recent and longest held); for cause-specific
and global measures of morbidity; and both formal and domestic labour.
Study Design
The hazard scores that were collected in Phase 1 will be re-coded
to allow a year-by-year analysis of each subject's hazard exposure.
This will enable the study to examine whether there are any particular
periods in the life course where hazard exposure results in a more
negative effect on health in early old age. Both age at exposure
and length of exposure will be examined.
New hazard scores,
that recognise the influence of domestic labour and child-rearing
on health, will also be constructed. The relative importance of
workplace and non-workplace hazards will then be compared. The first
analyses will consist of individual-level correlations between exposure
and health in later life, followed by a comparison of social distributions
of hazard exposure and morbidity.
Policy Implications
The research will contribute to the development of a particular
area of theory (life course influences on health and the accumulation
of specific risks) and methodology (analysis and interpretation
of data generated by lifegrid interviewing). It will further demonstrate
the usefulness of a data set collected under Phase 1 and will contribute
to knowledge and understanding of workplace influences on health.
The time-series analyses will allow the identification of any priority
age groups who may particularly benefit from policy interventions.
Additionally,
the research will address a key policy age group. An increasing
proportion of the British population is above retirement age and
early old age is the time of life when serious diseases become frequent
and much use is made of health services. Health in early old age
is also an important influence on the quality of life in these age
groups and on whether life after retirement offers the possibility
of a fulfilling 'Third Age'. By shedding light on workplace influences
on health at this stage of the life course, the study will also
help inform public health strategies and health improvement programmes.
Project Summary
Public health policy in the UK is committed to tackling health inequalities
across the lifecourse through strategies which tackle risk factors
in the settings in which people live and work. The workplace (paid
and unpaid) has been identified as one of the key settings for addressing
the risk factors which contribute to ill health and health inequalities.
This one-year
project extended research undertaken in David Blane's phase 1 project,
which traced and interviewed older people who had been surveyed
in their childhood as part of a 1930s study of health and development.
The phase 2 project added further information on hazard exposures
to the dataset, enabling new exposure measures to be created (for
example of domestic labour). Three hazards of the paid workplace
were examined (occupational fumes and dust, physically arduous work
and lack of job autonomy) together with, for women only, the length
of exposure to domestic labour. The lifecourse data collected by
the project made it possible to examine the longitudinal accumulation
of hazards and their relationship to health in early old age.
Key findings
- Age- and
sex-standardised height during a period of linear growth in childhood
was used as a marker of growth rate. This measure of childhood
growth was related to blood pressure in early old age, after comprehensive
adjustment for potential confounding factors, including adult
height. In contrast, the relationship between blood pressure and
adult height was eliminated after controlling for standardised
childhood height. These findings suggest that slower growth in
childhood may represent a risk, or be a marker of risk, for subsequent
higher blood pressure and potential arterial damage, as indicated
by higher pulse pressure.
- The association
of the measure of childhood growth with subsequent blood pressure
is too strong to be explained by the influence of birth weight
alone. This is in line with other research demonstrating that
childhood factors, as well as the uterine environment, are important
in determining future blood pressure.
- Lung function
in early old age, and specifically the forced expiratory volume
in one second (FEV1), is related to occupational exposure
to fumes and dust. Unlike blood pressure, this measure of adult
health is not related to height during childhood. This suggests
that there is not a single relationship between the lifecourse
and health in later life: the lifecourse relationships differ
between health outcomes.
- In analyses
of the relationship between the amount of domestic labour performed
by a woman during her lifetime and her health in early old age,
domestic labour proved to be a weak predictor of health. The relationship
strengthened when domestic labour was combined with the hazards
of formal paid employment which the woman had performed. This
suggests that it is domestic labour's contribution to the total
hazard load, rather than domestic labour per se, which is important
to later health. The inter-relationship between domestic labour
and paid employment is consistent with other research.
- Methodologically,
the project has developed an index of domestic labour, through
proxy measures of years of housework and childcare and an additional
weighting for heavy household work. These measures were transformed
into standard deviation units (z-scores) and summed to produce
a cumulative measure of lifetime domestic labour. The project
also demonstrated the need to include good quality data on childhood,
particularly with respect to height and growth, in any analysis
of health in later life.
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