Simple strategies for variance uncertainty in meta-analysis

Reliability of the measure of precision of the estimate is crucial; a correct value of the standard error of the point estimate entails that the resulting significance of the analysis is correctly stated and that confidence intervals have correct coverage probabilities. Stating an incorrect precision, on the contrary, can often result in biased and misleading results. In particular, in fixed-effects meta-analysis the overall estimator usually used in practice tends to have a variance higher than the optimal one even though this appears to be lower, just by chance. In performing a fixed-effects meta-analysis, individual estimates are weighted proportionately to the precision of the study. Such weighting is optimal only under the assumption that variances are known, which is never the case in practice. As a consequence, the estimator is sub-optimal and the resulting meta-analysis overstates the significance of the results: in particular, overstatements are dramatic when we summarise studies with small number of patients. Focusing the attention to the fixed-effects model, the main aim of this thesis is to investigate the behaviour of the precision of the overall estimator under different circumstances in order to assess how biased and incorrectly reported the overall variance of the commonly used estimator is and also to highlight in which circumstances improved estimates are deemed necessary. In fixed-effects meta-analysis, problems are related to poor estimates of the individual variances [] since these values are imprecise and both [theta] (the point estimator) and [V] (the overall variance estimator] depend upon them. Poorly estimated study variances can lead to the overall estimate of the variance of the treatment effect being badly underestimated. In order to evaluate the circumstances in which the imprecision in the estimates of [] badly affects [V], a number of simulations in different settings were performed. Under both the assumption of common and uncommon variance of the observations at the patient level, the average total number of patients per study plays an important role and this appears to be more important than the total number of each single study. Moreover, the allocation of patients per arm does not seem to be decisive for the estimated overall variance of the estimator even though balanced allocation as well as having roughly the same amount of patients per study yields better results. Furthermore, true to form, the higher the average number of patients per arm, the closer the estimator is to the optimal one, ie. the fewer the number of patients, the less precise the estimates of [] are and the greater the impact is on the results. Given the imprecision in the estimate of [], we may severely overstate the precision of [theta]. Better estimation of the variances are therefore investigated. Are there ways to account for the imprecise estimates of the within-studies variances? Shrunk variances were considered in order to assess whether borrowing information across variances would produce an overall variance estimate whose 'real' and 'average' dispersion were both closer to the optimal value. Combining measurements minimises the total 'Mean Squared Error'. Therefore, particularly when the nature of the problem is not to estimate each expected return separately but rather to minimise the total impact, shrinkage estimators represent a reasonable alternative to the classical estimators. This approach seems reasonable since the goal of this thesis is to minimise the real dispersion of the overall variance estimator. Moreover, shrinkage approaches (that combine variance information across studies and are study-specific at the same time) usually perform well under a wide range of assumptions about variance heterogeneity, behaving well both when the variances were truly constant as well as when they varied extensively from study to study. In particular, in this thesis the 'modified CHQBC estimator' suggested by Tong and Wang is used (where CHQBC stands for the James-type shrinkage estimator for variances initially proposed by Cui, Hwang, Qiu, Blades and Churchill). Results obtained via simulations (with different patterns for various variance schemes and divers average amounts of patients per study), emphasise that the estimator based on the 'shrunk variances' performs better than the one based on the estimated sample variances. Regardless of the variance structure across studies (homoscedasticity or uncommon variances), the estimator based on the shrunk variances performs optimally, even with an average small number of patients per trial, achieving almost optimal results even when the variances are strongly heterogenous and without relying on computational expensive procedures. Chapter 3 shows the results obtained if shrunk variances are used instead of the declared ones; moreover, this new approach is applied to some real data-sets showing how the declared variance tends to be higher in all cases and presumably closer the the 'real' optimal value. Finally, chapter 4 highlights the merits of this new approach to the problem of imprecise precision estimates in fixed-effects methods and also looks at the further work that needs to be done in order to improve results for this and other meta-analytical settings; this thesis, in fact, only considers the case of continuous normally distributed data ignoring binary, ordinal or survival deta meta-analyses. Moreover, despite the fact that the problem of estimating [] is particularly urgent and dramatic in the fixed-effects model, the estimation of [] might also be expected to influence random effects coverage probabilities especially when all studies in the meta-analyses are small (Brockwell and Gordon, 2001)

'Active ageing' and health: an exploration of longitudinal data for four European countries

'Active Ageing' has been promoted by the World Health Organisation (WHO) as a strategy for promoting the health and well-being of older people. Keeping active and involved in a range of activities not restricted to those associated with labour market participation may, it has been suggested, be beneficial for older people. In this research three domains of 'engagement' were considered: paid work, formal involvement (i. e. activities such as voluntary work, attendance at training courses and participation in political organisations) and informal involvement (i. e. activities such as providing care and help to family, and looking after grandchildren). Using the first two waves of the Survey of Health, Ageing and Retirement in Europe (SHARE) and the English Longitudinal Study of Ageing (ELSA), this thesis investigated both the cross-sectional association between socio-economic, demographic and health-related variables and engagement at baseline, and the longitudinal association between engagement at baseline and self-rated health (SRH) and depressive symptoms at follow-up (controlling for baseline measures of health). The analysis was based on sample members aged 50-69 at baseline in Denmark, France, Italy and England, countries selected to represent different welfare regimes. Cross-sectional findings showed that levels of engagement in paid work and formal activities varied across countries, whereas socio-economic, demographic and health related characteristics were similarly associated with engagement in all countries under study. This suggested that country-specific factors, such as retirement policies, might play an important role in determining older people's level of engagement in paid work. Cross-sectional results also suggested that work and formal engagement were associated with good health, whereas -among certain subpopulations -informal activities were associated with bad health. Longitudinal analyses showed that, in all countries, respondents in paid work at baseline were more likely to improve their SRH and less likely to become depressed than those who were `inactive'. Formal and informal engagement were not significantly associated with health at follow-up. Longitudinal results and associations found, however, might have been biased by the high rates of attrition, as multiple imputation techniques and sensitivity analyses suggested. The current research study confirms that engagement in work is an important pathway to health in late life. More attention, however, should be paid to people's working lives, the quality of work and work conditions as these may influence participation in, and withdrawal from, the labour market

The dynamics of paid and unpaid activities among people aged 50-69 in Denmark, France, Italy, and England

In the context of the current policy emphasis on extending working lives, we investigate whether the relationship between participation in paid work, other formal, and informal activities among people aged 50–69 is complementary or competitive. We also investigate differences in associations between countries using comparable longitudinal data from Denmark, France, Italy, and England. We find positive associations between informal and formal engagement in cross-sectional and longitudinal analyses. Paid work was negatively associated with formal and informal engagement, and respondents who stopped working were more likely to be engaged in formal (Denmark and France) and informal activities (England and Italy) at follow-up than respondents who continued working. However, the strongest predictor of formal and informal engagement at follow-up was baseline engagement. In the context of policy aims to extend working lives and broaden older people’s participation in other productive activities, new balances between work and other forms of engagement are still to be found

Mental health and social interactions of older people with physical disabilities in England during the COVID-19 pandemic: a longitudinal cohort study

BACKGROUND: The COVID-19 pandemic has affected mental health, psychological wellbeing, and social interactions. People with physical disabilities might be particularly likely to be negatively affected, but evidence is scarce. Our aim was to evaluate the emotional and social experience of older people with physical disabilities during the early months of the COVID-19 pandemic in England. METHODS: In this longitudinal cohort study, we analysed data from the English Longitudinal Study of Ageing collected in 2018–19 and June–July, 2020, from participants aged 52 years and older and living in England. Physical disability was defined as impairment in basic and instrumental activities of daily living (ADL) and impaired mobility. Depression, anxiety, loneliness, quality of life, sleep quality, and amount of real-time and written social contact were assessed online or by computer-assisted telephone interviews. Comparisons of experiences during the COVID-19 pandemic of people with and without a physical disability were adjusted statistically for pre-pandemic outcome measures, age, sex, wealth, ethnicity, presence of a spouse or partner, number of people in the household, and chronic pain. All participants with full data available for both surveys were included in the analyses. FINDINGS: Between June 3 and July 26, 2020, 5820 participants responded, 4887 of whom had full data available for both the pre-pandemic measures and the COVID-19 survey and were included in the analysis. During the COVID-19 pandemic, significantly more people with ADL impairment had clinically significant symptoms of depression (odds ratio 1·78 [95% CI 1·44–2·19]; p<0·0001), anxiety (2·23 [1·72–2·89]; p<0·0001), and loneliness (1·52 [1·26–1·84]; p<0·0001) than people without ADL impairment. Significantly more people with ADL impairment also had impaired sleep quality (1·44 [1·20–1·72]; p<0·0001) and poor quality of life than people without ADL impairment. The results were similar when disability was defined by impaired mobility. People with ADL impairment had less frequent real-time contact (0·70 [0·55–0·89]; p=0·0037) and written social contact (0·54 [0·45–0·64]; p<0·0001) with family than people without ADL impairment. Results for social contact were similar when disability was defined by impaired mobility. INTERPRETATION: People with physical disability might be at particular risk for emotional distress, poor quality of life, and low wellbeing during the COVID-19 pandemic, highlighting the need for additional support and targeted mental health services. FUNDING: Economic and Social Research Council/UK Research and Innovation, National Institute on Aging, National Institute for Health Research

Health Behaviors and Mental Health during the COVID-19 Pandemic: Evidence from the English Longitudinal Study of Aging

Stay-at-home and lockdown measures during the COVID-19 pandemic had an impact on health-related behaviors which in turn posed a risk to mental health, particularly among older people. In this study, we investigated how changes to health behaviors (physical activity, sleeping, eating, and drinking) impacted mental health (depression, quality of life, and life satisfaction) during and beyond the initial phase of the COVID-19 lockdown. Using data from Wave 9 (2018/19) and two COVID-19 sub-studies (June/July 2020; November/December 2020) of the English Longitudinal Study of Ageing (N = 4989), we found that health behaviors changes during lockdown were associated with poorer mental health in June/July 2020. However, in November/December 2020, higher depression, lower quality of life, and lower life satisfaction were more likely only among respondents who reported less physical activity, eating more, changes in sleep patterns, and drinking more alcohol. Public health programs should support healthy behaviors as we emerge from the pandemic

Mental health and self-rated health of older carers during the COVID-19 pandemic: evidence from England

OBJECTIVES: Older carers play a vital role supporting population health and protecting health and social care systems, yet there has been little research on understanding the effect of the pandemic on this group. In this paper, we investigate caring as a factor contributing to mental and self-rated health. METHODS: We investigate cross-sectional and longitudinal associations between provision of family care and mental health and wellbeing using longitudinal data from 5,149 members of the English Longitudinal Study of Ageing who responded to Wave 9 (2018/2019) and two COVID-19 sub-studies (June/July 2020; November/December 2020). We use logistic or linear regression models depending on outcome measures, controlling for pre-pandemic socioeconomic, demographic, and health-related variables. RESULTS: Before the pandemic, 21% of respondents cared for family or friends. Older people caring for someone inside the household mostly continued to provide care during the pandemic, with more than a quarter reporting an increase in the amount of care provided. Co-resident carers were disproportionately female, older, in the lowest wealth quintile, and more likely to report disability and chronic conditions. Both cross-sectional and longitudinal analyses suggest that, compared to those caring for people living outside the household, co-resident carers were significantly more likely to report poorer mental health and self-rated health. CONCLUSION: The health of older carers worsened disproportionately in the first year of the pandemic, a period also characterised by disruptions to support and closure of respite services. Support for carers’ mental and physical health requires greater policy attention, especially in pandemic conditions

Influences on employment transitions around the birth of the first child : the experience of Italian mothers

This article studies mothers’ employment transitions around childbirth. It argues that leaving employment around childbirth and returning after an interruption might depend on multiple influences: the micro-context of individual and household characteristics, the meso-context of women’s jobs and the macro-context of broader cultural and institutional factors. This conceptual model is tested using data from the Italian Institute of Statistics (ISTAT) ‘Family and Social Subjects (2009)’ survey. The findings confirm that mothers’ transitions out of employment are shaped by micro-characteristics such as education, meso-characteristics such as status and security of prior jobs, and macro geographical and temporal factors. Subsequent returns to employment also reflect micro and macro influences, as mothers born before 1950, with low education, and large families are less likely to return; but they seem less dependent upon prior job characteristics. The research highlights the importance of considering multiple levels of influence to understand the enabling factors of maternal employment.Publisher PDFPeer reviewe

Is grandparental childcare socio-economically patterned? Evidence from the English longitudinal study of ageing

Grandparents play a vital role in providing childcare to families. Qualitative research and evidence from parents raise concerns that it is grandparents who are socio-economically disadvantaged who provide grandchild care more regularly, perform more intensive tasks, and care out of financial necessity. However, no European studies have investigated these issues at population level. This study is based on grandparents aged 50+ who looked after grandchildren. Data are from wave 8 of the nationally representative English Longitudinal Study of Ageing (2016/2017). We exploit newly collected information on frequency of grandchild care, activities, and reasons for care. Using multinomial regressions, we first examined the extent to which grandparents’ socio-economic characteristics (wealth and education) are associated with frequency of grandchild care. Second, using logistic regressions, we investigated whether wealth and education are associated with activities and reasons for grandchild care. Overall, grandparents from disadvantaged socio-economic backgrounds were more likely to provide more regular childcare. Similarly, grandparents in the lowest wealth quartile were more involved in hands-on activities (cooking, taking/collecting grandchildren to/from school), whereas highly educated grandparents were more likely to help grandchildren with homework. Finally, better-off grandparents were more likely to look after grandchildren to help parents and provide emotional support and less likely to report difficulty in refusing to provide care. Our findings show that grandparental childcare varies by socio-economic status with more intensive childcare activities falling disproportionately on those with fewer resources, and this may act to exacerbate existing socio-economic inequalities in later life

The impact of caring for grandchildren on the health of grandparents in Europe: a lifecourse approach

Grandparents are becoming an increasingly important source of childcare. However, caring for grandchildren may have negative health consequences particularly for grandparents with intensive commitments such as those with primary care responsibilities. To date most studies on this issue are based on cross-sectional data and do not take earlier life circumstances into account. Thus, it is not known whether (or to what extent) the relationship between grandparental childcare and health is due to cumulative advantage or disadvantage throughout the lifecourse or to the impact of grandchild care per se. Employing data from waves 1–3 of the Survey of Health, Ageing and Retirement in Europe we investigated the longitudinal relationship between grandparental childcare (i.e. intensive and non-intensive) and health once cumulative histories of advantage or disadvantage are taken into account. We used latent class analysis to categorise respondents according to childhood socio-economic and health conditions drawing on life history information. Experiences in adulthood (e.g. periods of ill health) were also captured. We created a latent continuous physical health variable based on self- and observer-measured indicators. OLS regression was used to explore the association between physical health at wave 2 and grandparental childcare at baseline, controlling for conditions in childhood and adulthood, and for health and socio-economic characteristics. We found a positive longitudinal association between grandchild care and health even after earlier life health and socio-economic conditions were taken into account. However, this significant association was found only for grandmothers, and not grandfathers. Our results suggesting the health benefits of grandchild care are important given the widespread provision of grandparental childcare in Europe. However, further research on underlying mechanisms and causal pathways between grandchild care and grandparent health, as well as on gender differences in the pattern of association, is needed

Changes in older people's experiences of providing care and of volunteering during the COVID-19 pandemic

Engagement in socially productive activities, such as care provision and voluntary work, make important contributions to society, and may have been especially important during the coronavirus pandemic. They have also been associated with better health, well-being, and longer survival for older people. The ELSA COVID-19 Substudy provided data to allow for an exploration of how changes in caring and volunteering may have occurred during the pandemic, and to examine this in relation to factors such as sex, age, employment status, wealth, COVID-19 vulnerability and symptoms, and pre-pandemic experiences of health. Overall, there have been important changes in both the level of care provided by older people and the extent of their involvement in volunteering, with, on average, care provision more likely to have increased or stayed the same (65% of older carers reported this), and volunteering more likely to have decreased or stopped (61% of older volunteers reported this). However, a large number of older people took on new caring roles for someone outside the household (12%) and 4% of older people registered to volunteer as part of the NHS scheme. Both economic characteristics (such as paid employment and wealth) and health-related characteristics (such as being vulnerable, self-isolating, having experienced COVID-19 symptoms, and reporting functional limitations) were related to changes the frequency of caring and voluntary work. It is yet unclear how these changes in caring and volunteering have influenced older people’s health and well-being during the coronavirus outbreak. Investigating the impact of the pandemic on broader health and well-being outcomes for older people, the role of changes in care provision and volunteering in this, and how we might respond to this, is a crucial next step