Mary Barker

Process evaluation of complex interventions: Medical Research Council guidance

Process evaluation is an essential part of designing and testing complex interventions. New MRC guidance provides a framework for conducting and reporting process evaluation studies

Birth weight and body fat distribution in adolescent girls.

OBJECTIVE To examine the association between birth weight and body fat distribution in a group of adolescent girls. DESIGN A total of 216 white girls who were born in Southampton had their heights, weights, waist and hip circumferences, and skinfold thicknesses measured when they were aged between 14 and 16 years. RESULTS The girls who were smallest at birth, but who were fattest at time of measurement were the most centrally obese. In girls whose body mass index was above the median (21 kg/m2), the subscapular to triceps skinfold ratio rose by 9% for every kilogram decrease in birth weight. Among overweight girls, with a body mass index over 25, the ratio rose by 27% for every kilogram decrease in birth weight. CONCLUSION In adolescent girls, the tendency to store fat on the trunk rather than the limbs, seems to be programmed by growth in fetal life, and is most evident in those who are overweight.

Process evaluation in complex public health intervention studies: the need for guidance

Public health interventions aim to improve the health of populations or at-risk subgroups. Problems targeted by such interventions, such as diet and smoking, involve complex multifactorial aetiology. Interventions will often aim to address more than one cause simultaneously, targeting factors at multiple levels (eg, individual, interpersonal, organisational), and comprising several components which interact to affect more than one outcome.1 They will often be delivered in systems which respond in unpredictable ways to the new intervention.2 Recognition is growing that evaluations need to understand this complexity if they are to inform future intervention development, or efforts to apply the same intervention in another setting or population.1 Achieving this will require evaluators to move beyond a ‘does it work?’ focus, towards combining outcomes and process evaluation. There is no such thing as a typical process evaluation, with the term applied to studies which range from a few simple quantitative items on satisfaction, to complex mixed-method studies exploring issues such as the process of implementation, or contextual influences on implementation and outcomes. As recognised within MRC guidance for evaluating complex interventions, process evaluation may be used to ‘assess fidelity and quality of implementation , clarify causal mechanisms and identify contextual factors associated with variation in outcomes’.1 This paper briefly discusses each of these core aims for process evaluation, before describing current Medical Research Council (MRC) Population Health Sciences Research Network (PHSRN) funded work to develop guidance for process evaluations of complex public health interventions. ### Intervention implementation An important role for process evaluations is to examine the quantity and quality of what was actually implemented in practice, and why. This may inform implementation of similar interventions elsewhere, and facilitate interpretation of intervention outcomes. While notions of standardisation are central to implementation assessment, the nature of …

Growth in utero and blood pressure levels in the next generation

Epidemiological studies have consistently shown an inverse association between birth weight and systolic blood pressure in later life [1]. It is not known whether the cause of this association is intra-uterine programming in response to fetal malnutrition [2] or a genetic factor influencing both birth weight and blood pressure [3]. Family studies offer an important opportunity to distinguish between intra-uterine and genetic influences. If intra-uterine factors determine the inverse association between birth weight and blood pressure, it could be expected that offsprings systolic blood pressure is associated with maternal birth weight, but not with paternal birth weight. If, however, genetic factors do play a role, offsprings blood pressure would also be associated with paternal birth weight. Barker et al. [4] investigated these associations in 106 children of 70 fathers and 123 children of 77 mothers. Birth weight and blood pressure data in the parents were described previously [5]. In the present study, their offspring was divided in five parental birth weight strata and, according to Barker et al., the offsprings systolic blood pressures fell with increasing maternal birth weight (P for trend = 0.05), but were unrelated to paternal birth weight (P = 0.7) [4]. On the basis of these findings, the authors concluded that constrained growth of a female fetus by lack of nutrients causes persisting changes in its physiology and metabolism which lead to reduced fetal growth and raised blood pressure in the next generation. Therefore, public health policies to improve fetal growth in one generation may benefit succeeding generations. However, a closer look at their data shows that the opposite may be true. Using the three birth weight strata as defined for men and women in the original article describing the parents [5], it can be visualized that offsprings systolic blood pressure fell with increasing maternal as well as paternal birth weight (Fig. 1). This may suggest that genetic factors also play a role in the association between birth weight and blood pressure. It would be informative to test whether the association of parental birth weight with offsprings blood pressure is significantly different between mothers and fathers before and after adjustment for gestational age. If the relationship between low birth weight and raised blood pressure is caused by genetic factors, improvement of fetal growth may neither prevent the development of raised blood pressure in the first generation, nor in succeeding generations. Low birth weight may only serve …

Why is changing health-related behaviour so difficult?

OBJECTIVE To demonstrate that six common errors made in attempts to change behaviour have prevented the implementation of the scientific evidence base derived from psychology and sociology; to suggest a new approach which incorporates recent developments in the behavioural sciences. STUDY DESIGN The role of health behaviours in the origin of the current epidemic of non-communicable disease is observed to have driven attempts to change behaviour. It is noted that most efforts to change health behaviours have had limited success. This paper suggests that in policy-making, discussions about behaviour change are subject to six common errors and that these errors have made the business of health-related behaviour change much more difficult than it needs to be. METHODS Overview of policy and practice attempts to change health-related behaviour. RESULTS The reasons why knowledge and learning about behaviour have made so little progress in alcohol, dietary and physical inactivity-related disease prevention are considered, and an alternative way of thinking about the behaviours involved is suggested. This model harnesses recent developments in the behavioural sciences. CONCLUSION It is important to understand the conditions preceding behaviour psychologically and sociologically and to combine psychological ideas about the automatic and reflective systems with sociological ideas about social practice.

Constraints on food choices of women in the UK with lower educational attainment.

OBJECTIVE Women of lower educational attainment have less balanced and varied diets than women of higher educational attainment. The diets of women are vital to the long-term health of their offspring. The present study aimed to identify factors that influence the food choices of women with lower educational attainment and how women could be helped to improve those choices. DESIGN We conducted eight focus group discussions with women of lower educational attainment to identify these factors. We contrasted the results of these discussions with those from three focus group discussions with women of higher educational attainment. SETTING Southampton, UK. SUBJECTS Forty-two white Caucasian women of lower educational attainment and fourteen of higher educational attainment aged 18 to 44 years. RESULTS The dominant theme in discussions with women of lower educational attainment was their sense that they lacked control over food choices for themselves and their families. Partners and children exerted a high degree of control over which foods were bought and prepared. Womens perceptions of the cost of healthy food, the need to avoid waste, being trapped at home surrounded by opportunities to snack, and having limited skill and experience with food, all contributed to their sense they lacked control over their own and their familys food choices. CONCLUSIONS An intervention to improve the food choices of women with lower educational attainment needs to increase their sense of control over their diet and the foods they buy. This might include increasing their skills in food preparation.

Why women of lower educational attainment struggle to make healthier food choices: The importance of psychological and social factors

Women of lower educational attainment are more likely to eat unhealthy diets than women of higher educational attainment. To identify influences on the food choices of women with lower educational attainment, 11 focus groups (eight with women of lower, and three with women of higher educational attainment) were held. Using a semi-structured discussion guide, environmental, social, historical and psychological factors known to be associated with food choice were explored. Audio recordings were transcribed verbatim and thematically analysed. Compared to women of higher educational attainment, women of lower educational attainment had less control over their families’ food choices, less support for attempts to eat healthily, fewer opportunities to observe and learn good food-related practices, more negative affect, more perceived environmental constraints and more ambiguous beliefs about the consequences of eating a nutritious diet. These findings provide a starting point for taking forward the design of an intervention to improve the diets of young women.

Does living in a food insecure household impact on the diets and body composition of young children? Findings from the Southampton Women's Survey

Background Little is known about food insecurity in the UK. The aims of this study were to assess the prevalence and factors associated with food insecurity in a UK cohort and to examine whether the diets, reported health and anthropometry of young food insecure children differed from those of other children. Methods The Southampton Womens Survey is a prospective cohort study in which detailed information about the diets, lifestyle and body composition of 3000 women was collected before and during pregnancy. Between 2002 and 2006, 1618 families were followed up when the child was 3 years old. Food insecurity was determined using the Household Food Security Scale. The childs height and weight were measured; diet was assessed by food frequency questionnaire. Results 4.6% of the households were food insecure. Food insecurity was more common in families where the mothers were younger, smokers, of lower social class, in receipt of financial benefits and who had a higher deprivation score (all p<0.05). In comparison with other 3-year-old children, those living in food insecure households were likely to have worse parent-reported health and to have a diet of poorer quality, characterised by greater consumption of white bread, processed meat and chips, and by a lower consumption of vegetables (all p<0.05). They did not differ in height or body mass index. Conclusions Our data suggest that there are significant numbers of food insecure families in the UK. The poorer reported health and diets of young food insecure children have important implications for their development and lifelong health.

Behaviour, body composition and diet in adolescent girls

The purpose of the study was to examine the relationships between patterns of behaviour, body composition and diet in adolescent girls. A group of 328 14 to 16-year-old girls at school in Southampton, U. K. completed a questionnaire about their behaviour and lifestyle, and had their heights, weights and skinfold thicknesses measured. Of these girls, 286 also provided dietary information. Socially independent girls were more likely to smoke, and less likely to eat breakfast and meals with family. They consumed more snacks, chocolate and soft drinks. Girls who were dissatisfied with their weight dieted and exercised, watched less television and spent less of their money on food. Dissatisfaction with weight was strongly related to body mass index. The odds of being a dieter, an indication of dissatisfaction with weight, increased with every unit increase in body mass index, so that girls with a body mass index of 24 kg/m(2)and over were 19 times more likely to diet than those with a body mass index of 19 kg/m(2)or less. Girls who were less satisfied with their weight reported lower energy intakes but ate more green vegetables and brown bread than other girls. The eating habits of the girls were therefore influenced by the extent of their social lives and by their satisfaction with their weight.

Development of a 20-item food frequency questionnaire to assess a ‘prudent’ dietary pattern among young women in Southampton

Objective:To develop a short food frequency questionnaire (FFQ) that can be used among young women in Southampton to assess compliance with a prudent dietary pattern characterized by high consumption of wholemeal bread, fruit and vegetables, and low consumption of sugar, white bread, and red and processed meat.Methods:Diet was assessed using a 100-item interviewer-administered FFQ in 6129 non-pregnant women aged 20–34 years. In total, 94 of these women were re-interviewed 2 years later using the same FFQ. Subsequently, diet was assessed in 378 women attending SureStart Childrens Centres in the Nutrition and Well-being Study (NWS) using a 20-item FFQ. The 20 foods included were those that characterized the prudent dietary pattern.Results:The 20-item prudent diet score was highly correlated with the full 100-item score (r=0.94) in the Southampton Womens Survey (SWS). Both scores were correlated with red blood cell folate (r=0.28 for the 100-item score and r=0.25 for the 20-item score). Among the women re-interviewed after 2 years, the change in prudent diet score was correlated with change in red cell folate for both the 20-item (rS=0.31) and 100-item scores (rS=0.32). In the NWS a strong association between the 20-item prudent diet score and educational attainment (r=0.41) was observed, similar to that seen in the SWS (r=0.47).Conclusions:The prudent diet pattern describes a robust axis of variation in diet. A 20-item FFQ based on the foods that characterize the prudent diet pattern has clear advantages in terms of time and resources, and is a helpful tool to characterize the diets of young women in Southampton.