Health Statistics Quarterly 03 Autumn 1999 per cent could not be .... A breakdown of the causes of death revealed that of the 418 deaths, 38 per cent (157) were ...
Social patterning of health and mortality: children, aged 6–15 years, followed up for 25 years in the ONS Longitudinal Study Seeromanie Harding, Michael Rosato, Joanna Brown and Jillian Smith, ONS
Children aged 6–15 years in 1971 were followed up in the ONS Longitudinal Study for 25 years.The relationship between health and socio-economic circumstances at different stages of the life course was examined. Measures of socioeconomic position in childhood and adulthood were all associated with health and survival but the relationship appeared strongest with the most recent measure of socioeconomic position. This could be because of the young age of this sample as accidents and injuries accounted for most of the deaths. Health and survival was poorest among those who had experienced persisting socio-economic disadvantage.
BACKGROUND Several studies have examined the relationship between socioeconomic conditions in childhood and health in adult life.1,2,3 Recently research has focused on the relative importance of influences at different stages of the life course on adult health and disease risk.4,5,6 The notion of cumulative exposure over the life course has direct relevance to policies that aim to arrest or reverse social deprivation.7 In this study we use the ONS Longitudinal Study to assess the influence of socio-economic position at different stages in life on health and survival.
S TUDY SAMPLE AND METHOD OF ANALYSIS The Longitudinal Study is a record linkage study that contains information on individuals and households from censuses and routinely registered vital events. Details of the study can be found elsewhere. 8 It began in 1971 and is based on a representative 1 per cent sample (about 550,000) of the population of England and Wales. The current followup period extends to the end of 1995. Children aged 6–15 years at the 1971 Census and living in a private household were included in the analysis. This age restriction allowed children to be at least 16 in 1981 (school leaving age), so that they could be classified by their own socio-economic position in the 1981 and 1991 Censuses. Socio-economic position was measured using three established indicators 9,10 – occupation based social class, housing tenure and access to cars as reported at the census. Own social class in 1981 was not used as more than 25 per cent could not be classified. By 1991 however, the proportion unclassified reduced to 8 per cent. In comparison, less than 5
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Health Statistics Quar terly 03
per cent could not be classified by access to cars or by housing tenure at the three Censuses. Two outcome measures were used – death from any cause which occurred between Census day 1991 and the end of 1995, and the prevalence of limiting long-term illness in the 1991 Census. The relative importance of childhood and of own socio-economic position in later life on premature mortality during 1991–95, and on morbidity was examined by fitting these measures individually and simultaneously. Cumulative adverse exposure was measured by summing the number of occasions an individual was included in a particular socio-economic group at the 1971, 1981 and 1991 Censuses. Age and sex adjusted relative risks of mortality were measured using Cox regression, and of prevalence of limiting long-term illness using logistic regression.
Table 1
Autumn 1999
Intergenerational mobility of children aged 6–15 years in 1971: parental socio-economic position in 1971 by own socio-economic position in 1981* and 1991
Own socio-economic position 1981/91 Census
Parental socio-economic position 1971
Social Class*
Non-manual 1991 Manual 1991 Unclassified 1991
Non-manual % 50 26 25
Manual % 44 66 62
Yes % 77 61 37 24
No % 23 39 63 76
Owner occupied % 75 69 23 15
Privately rented % 8 10 17 17
Unclassified All=100% % 6 50,409 8 39,389 13 8,559
Car access
Conventionally in Longitudinal Study analyses, those who are not found at a subsequent census or by registration of a vital event are assumed to be lost to follow-up. Among all children who should have been aged at least 16 in 1981, 5 per cent were not found at the 1981 Census or by the end of follow-up. Loss to follow-up of study members was higher among children whose fathers were not classified to a social class (8 per cent) or were living in privately rented housing (7 per cent). This could introduce a small bias depending on whether they would have remained in the same social grouping or not had they been followed up. The numbers were small, however, and their exclusion is unlikely to have had any significant effect on the results.
FINDINGS
Access 1981 and 1991 Access 1981, no access 1991 No access 1981, access 1991 No access 1981 and 1991
All=100% 39,891 4,243 9,959 5,584
Housing tenure
Owner occupied 1981 and 1991 Owner occupied 1981, rented 1991 Rented 1981, owner occupied 1991 Rented 1981 and 1991 *
Local authority % 17 21 60 68
All=100% 29,142 4,514 15,221 10,800
Own social class in 1981 was not used because a large proportion was not classified to a class.
Trajectories of socio-economic position from childhood to later life Table 1 and Figure 1 show parental socio-economic position at the 1971 Census and own socio-economic position at the 1991 Census. All three indicators show very similar patterns. There is a high degree of similarity between parental and own circumstances. Those in the least advantaged socio-economic position in 1981 and 1991 were more than twice as likely to come from a disadvantaged than an advantaged background. Of all those who were in a manual social class in 1991, 66 per cent had a parent in a manual occupation. Similarly, of those without access to cars at both censuses, 76 per cent came from households with no car access and, of those living in rented housing at both censuses, 85 per cent were living in rented housing as children.
Figure 1
Intergenerational mobility of children aged 6–15 years in 1971: parental socio-economic position in 1971 by own socio-economic position in 1981* and 1991
Percentage 100 90 80
The influence of socio-economic circumstances in childhood and in later life on mortality and limiting long-term illness
70
Table 2 shows mortality by parental and own socio-economic position. With the exception of housing tenure in 1981, consistent gradients in mortality were seen for both parental and own socio-economic positions, which suggest that childhood and later circumstances contributed separately to mortality differences. For example, by parental car access, mortality was 43 per cent higher among those with no access to a car compared with that of those with access. By own car access in 1981 the differential increased to 63 per cent, and by 1991 it was more than twofold. However, after adjustment for both parental and own car access, the differentials attenuated. The earlier measures of car access were no longer significantly associated with mortality. Mortality was therefore much more strongly associated with current than with parental or earlier car access. Housing tenure showed a similar pattern; the most recent measure of housing tenure showed the strongest association with mortality differences after adjustment for parental housing.
40
60 50
30 20 10 0
NonManual class
Manual class
Car access
No car access
Owner Privately Local occupied rented Authority
Socio-economic cirumstances in childhood Most disadvantaged socio-economic position in adulthood Most advantaged socio-economic position in adulthood
*
Own social class in 1981 was not used because a large proportion was not classified to a class.
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Health Statistics Quar terly 03
Table 2
Autumn 1999
Age and sex adjusted relative risks of mortality, 1991–95, of children aged 6–15 years in 1971: parental socio-economic position in 1971 and own socio-economic position in 1981* and 1991 by socio-economic status
Table 3
Relative risks of limiting long-term illness in 1991 of children aged 6–15 years in 1971: parental socioeconomic position in 1971 and own socioeconomic position in 1981* and 1991
Unadjusted Unadjusted
Adjusted †
Adjusted †
Parental Social Class 1971* Non-manual Manual Unclassified
1.00 1.30 1.93 **
(0.96-1.75) (1.19-3.12)
1.00 1.23 1.72 **
(0.90-1.69) (1.06-2.81)
Own Social Class 1991* Non-manual Manual Unclassified
1.00 1.08 2.57 **
(0.80-1.47) (1.71-3.86)
1.00 1.01 2.35 **
(0.74-1.40) (1.55-3.56)
Parental car access 1971 Yes No
1.00 1.43 **
(1.09-189)
1.00 1.12
(0.82-1.52)
Own car access 1981 Yes No Non-private households
1.00 1.63 ** 1.74
(1.22-2.19) (0.89-3.43)
1.00 1.15 1.40
(0.82-1.61) (0.70-2.79)
Own car access 1991 Yes No Non-private households
1.00 2.72 ** 5.26 **
(2.02-3.66) (2.32-11.94)
1.00 2.50 ** 4.79 **
(1.81-3.46) (2.07-11.06)
Parental housing tenure 1971 Owner occupied 1.00 Privately rented 1.14 Local authority 1.16
(0.73-1.76) (0.87-1.56)
1.00 1.06 0.97
(0.67-1.69) (0.68-1.40)
Own housing tenure 1981 Owner occupied Privately rented Local authority Non-private households
1.00 0.94 1.32 1.63
(0.59-1.49) (0.97-1.78) (0.83-3.23)
1.00 1.86 1.16 1.35
(0.53-1.39) (0.78-1.72) (0.67-2.71)
Own housing tenure 1991 Owner occupied Privately rented Local authority Non-private households
1.00 1.34 1.59 ** 4.67 **
(0.83-2.17) (1.14-2.23) (2.06-10.61)
1.00 1.34 1.50 ** 4.37 **
(0.83-2.18) (1.04-2.17) (1.89-10.08)
Total number of deaths
202
202
Parental Social Class 1971* Non-manual Manual Unclassified
1.00 1.37** 1.83**
(1.26-1.49) (1.59-2.10)
1.00 1.10 ** 1.29 **
(1.01-1.20) (1.11-1.49)
Own Social Class 1991* Non-manual Manual Unclassified
1.00 1.62** 6.82**
(1.48-1.78) (6.15-7.56)
1.00 1.57 ** 6.56 **
(1.43-1.73) (5.90-7.29)
Parental car access 1971 Yes No
1.00 1.44**
(1.33-1.55)
1.00 1.10 **
(1.01-1.20)
Own car access 1981 Yes No Non-private households
1.00 1.72** 2.25**
(1.59-1.89) (1.88-2.69)
1.00 1.23 ** 1.70 **
(1.12-1.35) (1.41-2.05)
Own car access 1991 Yes No Non-private households
1.00 2.79** 11.85 **
(2.57-3.04) (9.58-14.66)
1.00 2.52 ** 10.51 **
(2.30 - 2.76) (8.46-13.06)
1.00 1.25** 1.42**
(1.10-1.41) (1.31-1.54)
1.00 1.04 0.97
(0.91-1.19) (0.88-1.08)
1.00 1.06 1.77** 2.37**
(0.93-1.21) (1.63-1.93) (1.97-2.83)
1.00 0.89 1.25 ** 1.69 **
(0.77-1.02) (1.11-1.39) (1.40-2.05)
1.00 1.50** 2.95** 12.60 **
(1.31-1.73) (2.71-3.21) (10.18-15.61)
1.00 1.49 ** 2.70 ** 11.42 **
(1.30-1.72) (2.46-2.98) (9.18-14.21)
Parental housing tenure 1971 Owner occupied Privately rented Local authority Own housing tenure 1981 Owner occupied Privately rented Local authority Non-private households Own housing tenure 1991 Owner occupied Privately rented Local authority Non-private households
* Own social class in 1981 was not used because a large proportion was not classified to a class. † Adjusted for own and parental socio-economic circumstances. ** p
