Michaela Benzeval

Income and health: the time dimension

It is widely recognised that poverty is associated with poor health even in advanced industrial societies. But most existing studies of the relationship between the availability of financial resources and health status fail to distinguish between the transient and permanent impact of poverty on health. Many studies also fail to address the possibility of reverse causation; poor health causes low income. This paper aims to address these issues by moving beyond the static perspective provided by cross-sectional analyses and focusing on the dynamic nature of peoples experiences of income and health. The specific objective is to investigate the relationship between income and health for adult participants in the British Household Panel Survey from 1991 to 1996/97. The paper pays particular attention to: the problem of health selection; the role of long-term income; and, the effect of income dynamics on health. The results confirm the general findings from the small number of longitudinal studies available in the international literature: long-term income is more important for health than current income; income levels are more significant than income change; persistent poverty is more harmful for health than occasional episodes; and, income reductions appear to have a greater effect on health than income increases. After controlling for initial health status the association between income and health is attenuated but not eliminated. This suggests that there is a causal relationship between low income and poor health.

Income inequality and population health

A number of studies have suggested that inequalities in the distribution of income may be an important cause of variations in the average level of population health among rich industrial nations. However, what is missing from the debate so far is any systematic review of evidence about the relationship between different measures of income distribution and indicators of population health. This paper aims to bridge that gap. First, it summarizes the recent English language literature on this topic and illustrates the methodological problems that weaken the inferences that can be derived from it. Secondly, it presents new empirical estimates of the relationship between different measures of income distribution, infant mortality and life expectancy based on the most authoritative data published to date. In contrast to most earlier studies, we find very little support for the view that income inequality is associated with variations in average levels of national health in rich industrial countries. Some possible explanations for these differences are outlined.

Employment transitions and mental health: an analysis from the British household panel survey

Study objective: To describe the impact of changes between employment and various forms of non-employment, and vice versa, on the psychological wellbeing of men and of women. Design: Separate multivariate models for men and for women were constructed to study the association between employment transitions and episodes of psychological distress (general health questionnaire). Participants: 13 359 employment transitions from 5092 people aged 16–74 years in the British household panel survey from 1991 to 1998. Main results: Transitions from paid employment to either unemployment or long term sick leave were associated with increased psychological distress for both men and women. Starting maternity leave or staying home to look after the family were also associated with psychological distress for women. Transitions from these roles to formal employment resulted in an improvement in mental health. There was some evidence that the effects were felt most strongly within six months of the transition. Conclusions: This paper provides further evidence that movements between paid employment and various forms of non-employment, in addition to unemployment, have an impact on mental health. The emphasis on transitions between a full range of employment states for both men and women from a large population based longitudinal study and a comparison of the relative magnitude of effects are unique features of this analysis. Interventions are suggested to minimise the psychological distress associated with transitions.

Grip Strength across the Life Course: Normative Data from Twelve British Studies

Introduction Epidemiological studies have shown that weaker grip strength in later life is associated with disability, morbidity, and mortality. Grip strength is a key component of the sarcopenia and frailty phenotypes and yet it is unclear how individual measurements should be interpreted. Our objective was to produce cross-sectional centile values for grip strength across the life course. A secondary objective was to examine the impact of different aspects of measurement protocol. Methods We combined 60,803 observations from 49,964 participants (26,687 female) of 12 general population studies in Great Britain. We produced centile curves for ages 4 to 90 and investigated the prevalence of weak grip, defined as strength at least 2.5 SDs below the gender-specific peak mean. We carried out a series of sensitivity analyses to assess the impact of dynamometer type and measurement position (seated or standing). Results Our results suggested three overall periods: an increase to peak in early adult life, maintenance through to midlife, and decline from midlife onwards. Males were on average stronger than females from adolescence onwards: males’ peak median grip was 51 kg between ages 29 and 39, compared to 31 kg in females between ages 26 and 42. Weak grip strength, defined as strength at least 2.5 SDs below the gender-specific peak mean, increased sharply with age, reaching a prevalence of 23% in males and 27% in females by age 80. Sensitivity analyses suggested our findings were robust to differences in dynamometer type and measurement position. Conclusion This is the first study to provide normative data for grip strength across the life course. These centile values have the potential to inform the clinical assessment of grip strength which is recognised as an important part of the identification of people with sarcopenia and frailty.

Life Course Trajectories of Systolic Blood Pressure Using Longitudinal Data from Eight UK Cohorts

Analysis of eight population-based and occupational cohorts from the UK reveals the patterns of change of blood pressure in the population through the life course.

A systematic review of the effect of retention methods in population-based cohort studies

BackgroundLongitudinal studies are of aetiological and public health relevance but can be undermined by attrition. The aim of this paper was to identify effective retention strategies to increase participation in population-based cohort studies.MethodsSystematic review of the literature to identify prospective population-based cohort studies with health outcomes in which retention strategies had been evaluated.ResultsTwenty-eight studies published up to January 2011 were included. Eleven of which were randomized controlled trials of retention strategies (RCT). Fifty-seven percent of the studies were postal, 21% in-person, 14% telephone and 7% had mixed data collection methods. A total of 45 different retention strategies were used, categorised as 1) incentives, 2) reminder methods, repeat visits or repeat questionnaires, alternative modes of data collection or 3) other methods. Incentives were associated with an increase in retention rates, which improved with greater incentive value. Whether cash was the most effective incentive was not clear from studies that compared cash and gifts of similar value. The average increase in retention rate was 12% for reminder letters, 5% for reminder calls and 12% for repeat questionnaires. Ten studies used alternative data collection methods, mainly as a last resort. All postal studies offered telephone interviews to non-responders, which increased retention rates by 3%. Studies that used face-to-face interviews increased their retention rates by 24% by offering alternative locations and modes of data collection.ConclusionsIncentives boosted retention rates in prospective cohort studies. Other methods appeared to have a beneficial effect but there was a general lack of a systematic approach to their evaluation.

Cohort Profile: West of Scotland Twenty-07 Study: Health in the Community

The West of Scotland Twenty-07 Study (Twenty-07 for short) was set up in 1986 by Sally Macintyre, Patrick West, Ellen Annandale, Kate Hunt, Graeme Ford, Rex Taylor, Sheila MacIver, Russell Ecob and Rory Williams at the Medical Research Council (MRC) Medical Sociology Unit, Glasgow (now the MRC Social and Public Health Sciences Unit). The aim of the Twenty-07 Study is to investigate, longitudinally, the social processes producing or maintaining inequalities in health by six key social positions: social class (defined, as was traditional at the time, as the main occupation of the head of household), gender, age, area of residence, marital status (now broadened to encompass family structure) and, in collaboration with other Unit programmes, ethnicity. Figure 1 illustrates the basic design of the study—it involves three cohorts 20 years apart—born around 1932 (dotted line), 1952 (dashed line) and 1972 (gray line)—with a planned follow-up period of 20 years, to provide information on 60 years of the life course. In the initial sweep, in 1987/88, the study members were thus approximately 15, 35 and 55 years of age and in the final planned round of face-to-face data collection, in 2007/08, they are approximately 35, 55 and 75 years. The study was designed to examine critical points in the lifespan; we are tracking the three cohorts as they make the transition from adolescence to working life (line a), through the main part of working life (line b) and from working life to retirement (line c). It was also designed to explore the effect of the historical context of people’s lives on their health and circumstances by comparing the different cohorts at the same age at different points in time (i.e. line d; 35-year-olds in 1987 and 2007, and line e; 55-year-olds in 1987 and 2007).

Partnership history and mental health over time

Study objective: To describe the mental health of men and women with differing histories of partnership transitions. Design: Data from nine waves of the British Household Panel Survey, a stratified general population sample, were used to calculate age standardised ratios and 95% confidence intervals for mean General Health Questionnaire scores for groups with different partnership transition histories. Participants:2127 men and 2303 women aged under 65 who provided full interviews at every survey wave. Main results: Enduring first partnerships were associated with good mental health. Partnership splits were associated with poorer mental health, although the reformation of partnerships partially reversed this. Cohabiting was more beneficial to men’s mental health, whereas marriage was more beneficial to women’s mental health. The more recently a partnership split had occurred the greater the negative outcome for mental health. Women seemed more adversely affected by multiple partnership transitions and to take longer to recover from partnership splits than men. Single women had good mental health relative to other women but the same was not true for single men relative to other male partnership groups. Conclusions: Partnership was protective of mental health. Mental health was worse immediately after partnership splits, and the negative outcomes for health were longer lasting in women. Future work should consider other factors that may mediate, confound, or jointly determine the relation between partnership change and health.

The daytime impact of DSM-5 insomnia disorder: Comparative analysis of insomnia subtypes from the Great British Sleep Survey

OBJECTIVE To profile the daytime impact of the proposed DSM-5 insomnia disorder diagnosis, with and without mental health, physical health, or other sleep disorder comorbidities; to better understand how specific daytime symptom patterns are associated with nighttime sleep in insomnia; and to compare childhood-onset and adulthood-onset insomnia disorder with respect to daytime dysfunction. METHOD Data were derived from the Great British Sleep Survey (GBSS), an open-access online population survey completed by adults who had a valid postcode and were residents of the United Kingdom. The primary variables of interest were the 6 areas that, according to the proposed DSM-5 criteria, may be impacted in the daytime by insomnia disorder: energy, concentration, relationships, ability to stay awake, mood, and ability to get through work. These variables were compared for those with versus those without insomnia disorder and across 5 insomnia subtypes (difficulty initiating sleep, difficulty maintaining sleep, early morning awakening, a combination of these 3 core symptoms, or nonrestorative sleep). Clinically comorbid insomnia presentations (insomnia disorder with poor mental health/poor physical health/additional sleep disorder symptoms) and insomnia disorder of childhood versus adult onset were also evaluated. RESULTS A total of 11,129 participants (72% female; mean age = 39 years) completed the GBSS between March 2010 and April 2011, of whom 5,083 screened as having possible insomnia disorder. Compared with those who did not have insomnia disorder, those with insomnia disorder reported greater impairment in all areas of daytime functioning (Cohen d range, 0.68-1.30). The greatest effects reflected negative impact on energy and mood. Participants with a combination of insomnia symptoms tended to be the most impaired (Cohen d range, 0.10-0.23), whereas no consistent differences emerged between the other 4 subtypes. Finally, individuals who had both insomnia disorder and poor mental health were consistently the most impaired comorbid group (Cohen d range, 0.15-0.65), and childhood-onset insomnia disorder had greater daytime impact than adult-onset insomnia disorder (P < .05 for energy; P < .01 for mood, concentration, and getting through work). CONCLUSIONS The severity of daytime impact of DSM-5 insomnia disorder varies by insomnia type. This finding has implications for the evaluation and management of insomnia in clinical practice.

Promoting Social Change: The Experience of Health Action Zones in England

When New Labour came to power in the UK in1997 it brought with it a strong commitment to reducing inequality and social exclusion. One strand of its strategy involved a focus on areabased initiatives to reduce the effects of persistent disadvantage. Health Action Zones (HAZs) were the first example of this type of intervention, and their focus on community-based initiatives to tackle the wider social determinants of health inequalities excited great interest both nationally and internationally. This article draws on findings from the national evaluation of the initiative. It provides an overview of the HAZ experience, and explores why many of the great expectations associated with HAZs at their launch failed to materialise. It suggests that, despite their relatively limited impact, it is best to consider that they made a good start in difficult circumstances rather than that they failed. As a result there are some important lessons to be learned about the role of complex community-based interventions in tackling seemingly intractable social problems for policy-makers, practitioners and evaluators.