Burden of disability in a post war birth cohort in the UK

Can measures of physical performance in mid-life improve the clinical prediction of disability in early old age? Findings from a British birth cohort study

BACKGROUND

Poor performance in physical tests such as grip strength and walking speed is a risk factor for disability in old age, although whether such measures improve the discrimination of clinical prediction models when traditional clinical risk factors are already known is not clear. The prevalence of disability in mid-life is relatively low and hence screening in this age group may present an opportunity for early identification of those at increased future risk who may benefit most from preventative interventions.

METHODS

Data were drawn from two waves of the Medical Research Council National Survey of Health and Development. We examined whether several chronic conditions, poor health behaviours and lower scores on three measures of physical performance (grip strength, chair rise speed and standing balance time) at age 53 were associated with self-reported mobility and/or personal care disability at age 69. We used the area under the curve statistic (AUC) to assess model discrimination.

RESULTS

At age 69, 44% (826/1855) of participants reported mobility and/or personal care disability. Our final clinical prediction model included sex, knee osteoarthritis, taking 2+ medications, smoking, increased BMI and poor performance in all three physical tests, with an AUC of 0.740 compared with 0.708 for a model which did not include the performance measures.

CONCLUSION

Measures of physical performance in midlife improve discrimination in clinical prediction models for disability over 16 years. Importantly, these and similar measures are also potential targets of future diet, exercise and pharmacological intervention in mid-life.

Chronic physical illness in early life and risk of chronic widespread and regional pain at age 68: evidence from the 1946 British birth cohort

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In a British birth cohort study, experience of serious illness in earlier life is associated with increased risk of chronic widespread pain at age 68.

This study aimed to examine the associations between serious illness in earlier life and risk of pain in old age using data from a large nationally representative British birth cohort, the Medical Research Council (MRC) National Survey of Health and Development (NSHD). Serious illness was defined as any experience of illness before age 25 requiring hospital admission of ≥28 days. Pain was self-reported at age 68, with chronic widespread pain (CWP) defined according to American College of Rheumatology criteria. Multinomial logistic regression was used to test associations of serious illness in early life with CWP, chronic regional pain (CRP), and other pain, with no pain as the referent category. Adjustment was made for sex, socioeconomic position, adult health status, health behaviours, and psychosocial factors. Of 2401 NSHD participants with complete data, 10.5% reported CWP (13.2% of women and 7.7% of men), 30.2% reported CRP, and 14.8% other pain. Compared with those with no history of serious illness, those who experienced serious illness in early life had a higher likelihood of CWP (relative risk ratio [RRR] = 1.62 [95% CI: 1.21-2.17]) and of CRP (RRR = 1.25 [95% CI: 1.01-1.54]) after adjusting for sex. In fully adjusted models, serious illness in early life remained associated with CWP (RRR = 1.43 [95% CI: 1.05-1.95]), but associations with CRP were attenuated (RRR = 1.19 [95% CI: 0.96-1.48]). There were no associations with other pain. These findings suggest that those who have experienced serious illness in earlier life may require more support than others to minimise their risk of CWP in later life.

An investigation of the healthy migrant hypothesis: Pre-emigration characteristics of those in the British 1946 birth cohort study

OBJECTIVES

The finding that migrants to high-income countries have lower rates of morbidity and mortality than non-migrants, controlling for socioeconomic position, is often attributed to the "healthy migrant" hypothesis, which suggests that only the healthiest individuals choose to migrate. This prospective study investigates the healthy migrant hypothesis in a cohort of British emigrants using pre-migration health indicators. We also investigate how early-life health characteristics relate to age at emigration and whether or not the emigrant returned home.

METHODS

Data are from the Medical Research Council National Survey of Health and Development, a nationally representative cohort study of people born in England, Scotland or Wales in March 1946. Childhood socio-economic position, health and cognitive ability were compared between 4,378 non-emigrants and 984 emigrants. Of the emigrants, 427 emigrated before age 20 and 557 after that age; 602 emigrants remained abroad and 382 returned home.

RESULTS

Emigrants had better childhood health (especially greater height), higher childhood socio-economic position and better childhood cognitive ability at age 8 than non-emigrants. Return emigrants were very similar to emigrants who remained abroad.

CONCLUSIONS

We found support for the healthy migrant hypothesis in a cohort of British emigrants. Our findings improve an understanding of how health is distributed within and across nations.

Gender and life course occupational social class differences in trajectories of functional limitations in midlife: findings from the 1946 British birth cohort

BACKGROUND

Older women and those of lower socioeconomic position (SEP) consistently constitute a larger portion of the disabled population than older men or those of higher SEP, yet no studies have examined when in the life course these differences emerge.

METHODS

Prevalence of self-reported limitations in the upper body (gripping or reaching) and lower body (walking or stair climbing) at 43 and 53 years were utilized from 1,530 men and 1,518 women from the British 1946 birth cohort. Generalized linear models with a binomial distribution were used to examine the effects of gender, childhood and adult SEP, and the differences in the SEP effects by gender on the prevalence of limitations at age 43 years and changes in prevalence from 43 to 53 years.

RESULTS

For both genders, the prevalence of upper and lower body limitations were reported at 3%-5% at age 43 years. However, by age 53 years, women's upper body limitations had increased to 28% and lower body limitations to 21%, whereas men's limitations had only increased to 12% and 11%, respectively. Men and women whose father's occupation was manual or whose adult head of household occupation was manual had higher prevalence of both limitations compared with those with non-manual backgrounds. These differences widened with age, especially in women. The effect of adult SEP on the prevalence of limitations was stronger than that of childhood SEP and was partly mediated by educational attainment.

CONCLUSION

Our findings provide the first evidence that prevention of disability in old age should begin early in midlife, especially for women from manual occupation households.

The development of life course epidemiology

The present paper reviews the development of life course epidemiology since its origins during the 1990s from biological programming, birth cohort research and the study of health inequalities. Methods of studying the life course are examined, including birth cohort studies, linked register datasets and epidemiological archaeology. Three models of life course epidemiology are described: critical periods, accumulation, and pathways. Their conceptual and empirical differentiation can be difficult, but it is argued that accumulation is the underlying social process driving life course trajectories, while the critical period and pathway models are distinguished by their concern with specific types of aetiological process. Among the advantages of the accumulation model are predictive power, aetiological insights, contributions to health inequality debates and social policy implications. It is emphasised that the life course approach is not opposed to, or an alternative to, a concern with cross-sectional and current effects; major social disruption can have a large and immediate impact on health. Other limitations of the life course approach include a spectrum of impact (life course effects can be strong in relation to physiology, but often are weaker in relation to behaviour and psychological reactions to everyday life) and, more speculatively, the possibility that life course effects are diluted in the older age groups where morbidity and mortality are highest. Three issues for the future of life course epidemiology are identified. Many life course data are collected retrospectively. We need to know which items of information are recalled with what degree of accuracy over how many decades; and what methods of collecting these retrospective data maximise accuracy and duration. Second, the two partners in life course research need to take more seriously each other's disciplines. Social scientists need to be more critical of such measures as self-assessed health, which lacks an aetiology and hence biological plausibility. Natural scientists need to be more critical of such concepts as socio-economic status, which lacks social plausibility because it fails to distinguish between social location and social prestige. Finally, European comparative studies can play an important part in the future development of life course epidemiology if they build on the emerging infrastructure of European comparative research.

Life course determinants for early disability pension: a follow-up of Norwegian men and women born 1967–1976

BACKGROUND

Most studies on disability pension (DP) have focused on work conditions, socio-economic status and other contemporary factors. We wanted to study possible determinants of an early DP with a life course perspective within a large register-based cohort, with a main focus on the biological and social factors from childhood.

METHODS

We established a longitudinal, population-based cohort of all persons liveborn in Norway between 1967 and 1976. Through linkage between several national registers we obtained personal data on biological/health related as well as social background factors. After excluding persons who died, emigrated or were granted a DP before age 20 years (at which age follow-up started) and persons who did not become gainfully employed during the study period, the study population consisted of 595,393 persons. They were categorized into four strata according to gender and educational attainment. Adjusted hazard ratios (HR) for granting a DP until the end of 2003 and the corresponding population attributable risks (PAR) were computed.

RESULTS

A total of 9,649 persons (1.6%) were granted a DP during follow-up. The disability risk was slightly higher among women than among men (1.7% vs. 1,5%). The following PARs were found: birth weight below the mean 5.7%, chronic childhood disease 6.8%, maternal marital status 4.4% and parental disability 8.8%. Low educational achievement was highly associated with DP, with a PAR more than twice as high as the overall PAR for the childhood factors.

CONCLUSIONS

Early DP is associated with several biological and social background factors from childhood. It also shows a strong dependency on educational achievement.

Long term outcome after poliomyelitis in different health and social conditions

OBJECTIVE

To examine and compare the long term outcome after polio in an east European and a west European country with different access to rehabilitation and with different medical and social conditions.

DESIGN AND SETTING

The patients who were acutely hospitalised for polio 1950-54 in the University Hospital in Bergen, Norway and 1958 in the University Hospital in Tartu, Estonia received the mailed questionnaire in the period between January 1998 and December 1998.

PATIENTS

Patient files concerning 334 patients hospitalised in Tartu and 243 patients hospitalised in Bergen were obtained; of these 128 Estonian and 148 Norwegian patients were re-examined.

MAIN RESULTS

Despite more pronounced disability in the acute stage, significantly more Norwegian patients were working full time and part time in 1998 (p<0.0001) and also through the period 1958-1998. In both countries, 30% of patients had manual work and 18% changed profession during their career. Low income (below 50% of national average) was reported by 73% of Estonian and 35% of Norwegian patients (p<0.0001). Except for the odds ratio for muscular pain of 1.89 (95%CI =1.14 to 3.14) for Norwegian patients, new symptoms indicating late progression did not differ. Norwegian patients were more independent with significantly less need for assistance in housekeeping (p=0.02), whereas the use of orthopaedic devices did not differ.

CONCLUSIONS

The long term outcome after polio is different in eastern and western Europe. Access to continuous rehabilitation seems to maintain physical independence in polio patients, improves their ability to earn their own income, and lessens the need for disability pensions.

Lifetime risk factors for women's psychological distress in midlife

Research on the causes of psychological distress in women in midlife has focused on current adversity and hormonal changes associated with menopause and paid less attention to possible risk factors across the life course. We examined the factors in childhood, adolescence and earlier adult life that show persisting effects on psychological symptoms reported annually over a 6 year period (47-52 years) using prospective data on a cohort of 1500 British women who have been followed since their birth in 1946. Even after taking into account the powerful effect of recent life stress, this study found that women with a high level of psychological distress had different life course trajectories than those with less distress. They were more likely to have scored highly on the neuroticism scale or exhibited antisocial behaviour when they were teenagers, and to have had prior experience of mental and physical health problems in adult life. Those whose parents had divorced reported more distress in midlife, particularly if they too had experienced marital breakdown. These factors accounted for the associations between some of the adult sources of risk, particularly those to do with interpersonal difficulties or poor adult socioeconomic circumstances, and psychological distress in midlife. There was no evidence that concurrent menopausal status had any effect on the level of psychological symptoms except for those women on hormone replacement therapy who had a small and independent additional risk. More attention to a long term temporal perspective is warranted in research on the causes of psychological distress in women at midlife.

Physical disability in The Netherlands: prevalence, risk groups and time trends

Physical disability represents an important health indicator of western populations. In this paper the prevalence of physical disabilities in The Netherlands is presented for four domains of disability-visual, hearing, mobility and activities of daily living (ADL) disability-with a focus on risk groups and time trends.Cross-sectional national health survey data (NetHIS) of 9 y, 1990-1998, presenting data on 62 352 persons of 16 y or over were used. All data were self-reported. About one-eighth of the research population had a physical disability, ie had at least major difficulty with one or more functions such as walking, seeing, hearing and washing. This figure increased from 1.7% in the age group of 16-24 y to 44.1% in the age group of 75 y or older. Risk groups were women, those living alone, those who were divorced or widowed and those with a low educational level. In the period 1990-1998, the prevalence did not change with the exception of the prevalence of mobility disability which dropped slightly with 0.2 percentage points per year due to decreasing prevalences among men. One conclusion is that the prevalence of disability is high and stable, and expected to increase in the future due to the ageing of the population.

Socioeconomic status and the prevalence of health problems among married couples in late midlife

OBJECTIVES

This study analyzed the association between socioeconomic status (SES) and the prevalence of mutually occurring health problems among married couples in late midlife.

METHODS

Data consisted of 4746 married couples aged 51 to 61 years from the 1992 US Health and Retirement Study. Two health measures were used: (1) self-assessed health status and (2) an index of functional limitations and activity restrictions. SES indicators were household income, education, and insurance coverage.

RESULTS

In general, after adjustment for age cohort, a strong association was found between the health of a married individual and the health of his or her spouse. SES was highly associated with the joint occurrence of health problems among marriage partners.

CONCLUSIONS

Public health policy should pay particular attention to the interaction between health, SES, and interpersonal relationships.

A prospective study of limiting longstanding illness in early adulthood

BACKGROUND

Chronic illness and disability are of increasing public health importance but little is known about the lifetime influences involved in their onset and progression. We aim to (i) establish whether an individual's rating of limiting illness is stable over a 10-year period from age 23 to 33; (ii) assess the relationship between childhood and adult disability; and (iii) identify lifecourse influences on limiting illness in early adulthood.

METHODS

Data were from the 1958 British birth cohort, including the original birth survey and follow-ups at ages 7, 11, 16, 23 and 33 years. Limiting longstanding illness was the outcome at both ages 23 and 33. Potential predictors included childhood health and physical development, socioeconomic conditions in early life and adulthood, and behavioural factors. We estimated the effect of potential explanatory factors using logistic regression, in both univariate and multivariate analyses, separately for limiting illness at 23 and 33 years.

RESULTS

Prevalence of limiting illness increased from 5.1% (men) and 4.1% (women) at age 23 to 6% for both sexes at age 33. Risk of limiting illness at age 33 was greater for those reporting an illness at age 23 (29.4%, compared with 4.7% of those without illness), though the majority (66%) of 33-year limiting illnesses had no previous record at age 23 or for childhood. Multivariate analysis of limiting illness at age 23 confirmed the high risk for those with childhood disability and also established two further major predictors, namely, injury (adjusted odds ratio [OR] = 1.42, 95% CI: 1.09-1.86) and intermediate socio-emotional status (adjusted OR = 1.73, 95% CI: 1.29-2.31). Additional risks were identified for limiting illness at age 33, including: (i) injury in the preceding 10 years (adjusted OR = 1.55, 95% CI : 1.18-2.04); (ii) body mass index (BMI), for which the relationship was non-linear, with elevated risks for the underweight (adjusted OR = 1.53, 95% CI: 1.03-2.26) and overweight (OR = 1.28, 95% CI: 0.87-1.89); (iii) childhood disadvantage at either or both ages 7 and 11 (adjusted OR = 1.53, 95% CI : 1.07-2.17); and (iv) height at age 7, with a significant non-linear relationship (the adjusted OR for height less than 15th percentile was 1.43 and for height more than the 85th percentile, 1.30).

CONCLUSIONS

Both childhood and adult factors predict limiting illness in early adulthood. Childhood is important because some adult illnesses originate in early life, and also because childhood environment influences the risk of adult limiting illness several years later. Our findings suggest that studies seeking to understand the causes of limiting illness, that currently tend to focus exclusively on contemporary factors, need also to consider the contribution of environment in early life.

Impairments, disabilities and needs assessment among non-fatal war injuries in south Lebanon, Grapes of Wrath, 1996

STUDY OBJECTIVE

To examine the impact of non-fatal war related injuries on physical disability in a group of war wounded civilians and to assess their needs.

DESIGN

Cross sectional study. Home interviews were conducted using a structured interview schedule around one month after the injury, to assess impairments, disabilities, and needs.

STUDY POPULATION AND SETTING

War wounded persons in towns and villages in South Lebanon during the attack "Grapes of Wrath" in 1996.

RESULTS

The majority of the study population were young and in their productive age, mostly injured in the street or while hiding in open shelters. Around half of the injuries resulted in impairments, but, there were no age, gender or geographical differentials by severity of impairment. Almost one third (29%) of the students enrolled in schools at the time of the injury reported failure to continue their education and 42% of the working members lost their jobs with no potential for 34% of them to resume their former jobs. The impact of the injury on impairments, motor disabilities and physical independence was highest for injuries to the lower limbs (age and sex adjusted risk ratio (RR) 1.62, 95% confidence intervals (CI) 1.25, 2.10; 2.98, 95% CI 2.09, 4.23; and 2.13, 95% CI 1.39, 3.27, respectively). Despite the acute and early relief services provided by all those concerned at the time of the injury, when asked about unmet needs, the majority of the impaired (66%) reported the need for additional services, mostly medical in nature. The degree of disability was a salient factor for the need for rehabilitative services but not for medical services.

CONCLUSIONS

The chronic and diverse needs of people with war injuries are often neglected and underestimated by the governmental institutions and relief agencies. Research funds as well as services should be allocated to tackle the long term and continuous health and social needs of those injured and their families.

Poliomyelitis: long-time consequences for social life

In a study of 102 consecutive patients hospitalized for previous poliomyelitis, we found that 70 patients had continued education after elementary school and 18 were academics. This is a higher proportion than in the general Norwegian population. All 14 patients with paraparesis had continued education after elementary school, while as many as 12 of 18 patients with a university degree had widespread pareses in the acute phase. Of the patients 46 worked or had worked full-time up to 60 years of age. Only 29 patients were receiving a disabled pension. Another 9 patients had neither been employed nor received any pension, all housewives. Nine of 14 patients with paraparesis were working full-time, only 2 received disabled pension. Among the 35 patients with persisting widespread pareses, 11 were still in full-time work and 7 were working part-time. The employment rate among the patients in this study was nearly identical to the age-correlated general employment rate in Norway. Our conclusion is that polio patients are doing well in society; they have taken education, are working, and are generally self-supported. The degree of pareses does not seem to have been the most determining factor for their educational and professional activity.

The impact of socioeconomic status on health functioning as assessed by the SF-36 questionnaire: the Whitehall II Study

OBJECTIVES

This study measured the association between socioeconomic status and the eight scale scores of the Medical Outcomes Study short form 36 (SF-36) general health survey in the Whitehall II study of British civil servants. It also assessed, for the physical functioning scale, whether this association was independent of disease.

METHODS

A questionnaire containing the SF-36 was administered at the third phase of the study to 5766 men and 2589 women aged 39 through 63 years. Socioeconomic status was measured by means of six levels of employment grades.

RESULTS

There were significant improvements with age in general mental health, role-emotional, vitality, and social functioning scale scores. In men, all the scales except vitality showed significant age-adjusted gradients across the employment grades (lower grades, worse health). Among women, a similar relationship was found for the physical functioning, pain, and social functioning scales. For physical functioning, the effect of grade was found in those with and without disease.

CONCLUSIONS

Low socioeconomic status was associated with poor health functioning, and the effect sizes were comparable to those for some clinical conditions. For physical functioning, this association may act both via and independently of disease.

Women's health in midlife: the influence of the menopause, social factors and health in earlier life

OBJECTIVE

To describe the health symptoms of a large representative sample of British women at age 47 years, and to examine the influence of the menopause allowing for social factors and health in earlier adult life.

DESIGN

A national prospective birth cohort study. Information on health problems, menstrual cycle, use of hormone replacement therapy and life stress at 47 years was collected using a postal questionnaire. Information on health, smoking behaviour and educational attainment earlier in life had been collected at previous home visits.

SETTING

England, Scotland and Wales.

POPULATION

A general population sample of 1498 women, 84% of those sent a questionnaire.

MAIN OUTCOME MEASURE

Twenty self-reported health symptoms over the previous 12 months.

RESULTS

Women who had experienced an early natural menopause had a strongly raised risk of vasomotor symptoms (hot flushes or night sweats), sexual difficulties (vaginal dryness or difficulties with intercourse) and trouble sleeping. However, there was little or no excess risk of other somatic or psychological symptoms. In contrast, all types of symptoms were more common among women who had had a hysterectomy or were users of hormone replacement therapy. Women with the least education, stressful lives, or a previous history of poor physical and psychological health at age 36 also reported more symptoms at 47 years compared with other women, but adjustment for these factors in a logistic regression model did not affect the relations between symptoms and current menopausal status. For vasomotor symptoms, postmenopausal women had an adjusted odds ratio of 4.7 (95% CI 2.6-8.5) and perimenopausal women had an adjusted odds ratio of 2.6 (95% CI 1.9-3.5) compared with premenopausal women. Corresponding adjusted odds ratios for sexual difficulties were 3.9 (95% CI 2.1-7.1) and 2.2 (95% CI 1.4-3.2), and for trouble sleeping were 3.4 (95% CI 1.9-6.2) and 1.5 (95% CI 1.1-2.0).

CONCLUSIONS

Specific symptoms were clearly associated with the natural menopause. More general health concerns were common among women in middle life, particularly among those with stressful lives, or those who had had a hysterectomy or started taking hormone replacement therapy before they were postmenopausal. Appropriate advice and support needs to be easily accessible.