Sally Haw

Using natural experiments to evaluate population health interventions: new Medical Research Council guidance

Natural experimental studies are often recommended as a way of understanding the health impact of policies and other large scale interventions. Although they have certain advantages over planned experiments, and may be the only option when it is impossible to manipulate exposure to the intervention, natural experimental studies are more susceptible to bias. This paper introduces new guidance from the Medical Research Council to help researchers and users, funders and publishers of research evidence make the best use of natural experimental approaches to evaluating population health interventions. The guidance emphasises that natural experiments can provide convincing evidence of impact even when effects are small or take time to appear. However, a good understanding is needed of the process determining exposure to the intervention, and careful choice and combination of methods, testing of assumptions and transparent reporting is vital. More could be learnt from natural experiments in future as experience of promising but lesser used methods accumulates.

Changes in child exposure to environmental tobacco smoke (CHETS) study after implementation of smoke-free legislation in Scotland: national cross sectional survey

Objective To detect any change in exposure to secondhand smoke among primary schoolchildren after implementation of smoke-free legislation in Scotland in March 2006. Design Comparison of nationally representative, cross sectional, class based surveys carried out in the same schools before and after legislation. Setting Scotland. Participants 2559 primary schoolchildren (primary 7; mean age 11.4 years) surveyed in January 2006 (before smoke-free legislation) and 2424 in January 2007 (after legislation). Outcome measures Salivary cotinine concentrations, reports of parental smoking, and exposure to tobacco smoke in public and private places before and after legislation. Results The geometric mean salivary cotinine concentration in non-smoking children fell from 0.36 (95% confidence interval 0.32 to 0.40) ng/ml to 0.22 (0.19 to 0.25) ng/ml after the introduction of smoke-free legislation in Scotland—a 39% reduction. The extent of the fall in cotinine concentration varied according to the number of parent figures in the home who smoked but was statistically significant only among pupils living in households in which neither parent figure smoked (51% fall, from 0.14 (0.13 to 0.16) ng/ml to 0.07 (0.06 to 0.08) ng/ml) and among pupils living in households in which only the father figure smoked (44% fall, from 0.57 (0.47 to 0.70) ng/ml to 0.32 (0.25 to 0.42) ng/ml). Little change occurred in reported exposure to secondhand smoke in pupils own homes or in cars, but a small decrease in exposure in other peoples homes was reported. Pupils reported lower exposure in cafes and restaurants and in public transport after legislation. Conclusions The Scottish smoke-free legislation has reduced exposure to secondhand smoke among young people in Scotland, particularly among groups with lower exposure in the home. We found no evidence of increased secondhand smoke exposure in young people associated with displacement of parental smoking into the home. The Scottish smoke-free legislation has thus had a positive short term impact on young peoples health, but further efforts are needed to promote both smoke-free homes and smoking cessation.

Set points, settling points and some alternative models: Theoretical options to understand how genes and environments combine to regulate body adiposity

The close correspondence between energy intake and expenditure over prolonged time periods, coupled with an apparent protection of the level of body adiposity in the face of perturbations of energy balance, has led to the idea that body fatness is regulated via mechanisms that control intake and energy expenditure. Two models have dominated the discussion of how this regulation might take place. The set point model is rooted in physiology, genetics and molecular biology, and suggests that there is an active feedback mechanism linking adipose tissue (stored energy) to intake and expenditure via a set point, presumably encoded in the brain. This model is consistent with many of the biological aspects of energy balance, but struggles to explain the many significant environmental and social influences on obesity, food intake and physical activity. More importantly, the set point model does not effectively explain the ‘obesity epidemic’ – the large increase in body weight and adiposity of a large proportion of individuals in many countries since the 1980s. An alternative model, called the settling point model, is based on the idea that there is passive feedback between the size of the body stores and aspects of expenditure. This model accommodates many of the social and environmental characteristics of energy balance, but struggles to explain some of the biological and genetic aspects. The shortcomings of these two models reflect their failure to address the gene-by-environment interactions that dominate the regulation of body weight. We discuss two additional models – the general intake model and the dual intervention point model – that address this issue and might offer better ways to understand how body fatness is controlled.

An overview of prevention of multiple risk behaviour in adolescence and young adulthood

The observed clustering, and shared underlying determinants, of risk behaviours in young people has led to the proposition that interventions should take a broader approach to risk behaviour prevention. In this review we synthesized the evidence on what works to prevent multiple risk behaviour (focusing on tobacco, alcohol and illicit drug use and sexual risk behaviour) for policy-makers, practitioners and academics. We aimed to identify promising intervention programmes and to give a narrative overview of the wider influences on risk behaviour, in order to help inform future intervention strategies and policies. The most promising programme approaches for reducing multiple risk behaviour simultaneously address multiple domains of risk and protective factors predictive of risk behaviour. These programmes seek to increase resilience and promote positive parental/family influences and/or healthy school environments supportive of positive social and emotional development. However, wider influences on risk behaviour, such as culture, media and social climate also need to be addressed through broader social policy change. Furthermore, the importance of positive experiences during transition periods of the child-youth-adult phase of the life course should be appropriately addressed within intervention programmes and broader policy change, to reduce marginalization, social exclusion and the vulnerability of young people during transition periods.

Smoking restrictions in the home and secondhand smoke exposure among primary schoolchildren before and after introduction of the Scottish smoke-free legislation

Objective: To examine change in home smoking restrictions one year after introduction of Scottish smoke-free legislation, and whether type of restriction impacts upon secondhand smoke (SHS) exposure among children. Design: Comparison of nationally representative, cross-sectional, class-based surveys carried out in the same schools before and after legislation. Participants: 2527 primary schoolchildren (aged around 11 years) surveyed in January 2006 and 2379 in January 2007. Outcome measures: Self-reported home smoking restrictions, salivary cotinine concentrations. Results: Children surveyed after implementation of legislation were more likely than those surveyed before its introduction to report complete home smoking restrictions as opposed to partial (relative risk ratio (partial vs complete) 0.75 (95% CI 0.63 to 0.89) or no restrictions (RR (no restrictions vs complete) 0.50 (0.40 to 0.63). Children living with smokers were less likely to have stringent restrictions in place compared with children living with non-smokers (for both vs neither parents smoke: RR (partial vs complete) 18.29 (13.26 to 25.22) and RR (no restrictions vs complete) 104.73 (70.61 to 155.33). Among smoking households, restriction type varied according to the number and gender of parents who smoke. In both smoking and non-smoking households, children’s SHS exposure was directly related to type of home smoking restriction, with lowest exposures among those reporting complete restrictions. Conclusion: This study has shown an increase in the proportion of children reporting a complete ban on smoking in their household after the introduction of smoke-free legislation and supports growing evidence of the wider impact smoke-free legislation can have on smoker behaviour. However, quitting smoking combined with complete home smoking bans will still afford children the best protection from SHS exposure.

Interventions to prevent substance use and risky sexual behaviour in young people: a systematic review.

AIMSnTo identify and assess the effectiveness of experimental studies of interventions that report on multiple risk behaviour outcomes in young people.nnnMETHODSnA systematic review was performed to identify experimental studies of interventions to reduce risk behaviour in adolescents or young adults and that reported on both any substance (alcohol, tobacco and illicit drug) use and sexual risk behaviour outcomes. Two authors reviewed studies independently identified through a comprehensive search strategy and assessed the quality of included studies. The report was prepared in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.nnnRESULTSnFrom 1129 papers, 18 experimental studies met our inclusion criteria, 13 of which were assigned a strong or moderate quality rating. The substantial heterogeneity between studies precluded the pooling of results to give summary estimates. Intervention effects were mixed, with most programmes having a significant effect on some outcomes, but not others. The most promising interventions addressed multiple domains (individual and peer, family, school and community) of risk and protective factors for risk behaviour. Programmes that addressed just one domain were generally less effective in preventing multiple risk behaviour.nnnCONCLUSIONSnThere is some, albeit limited, evidence that programmes to reduce multiple risk behaviours in school children can be effective, the most promising programmes being those that address multiple domains of influence on risk behaviour. Intervening in the mid-childhood school years may have an impact on later risk behaviour, but further research is needed to determine the effectiveness of this approach.

Clustering of substance use and sexual risk behaviour in adolescence: Analysis of two cohort studies

Objectives The authors aimed to examine whether changes in health risk behaviour rates alter the relationships between behaviours during adolescence, by comparing clustering of risk behaviours at different time points. Design Comparison of two cohort studies, the Twenty-07 Study (‘earlier cohort’, surveyed in 1987 and 1990) and the 11-16/16+ Study (‘later cohort’, surveyed 1999 and 2003). Setting Central Clydeside Conurbation around Glasgow City. Participants Young people who participated in the Twenty-07 and 11-16/16+ studies at ages 15 and 18–19. Primary and secondary outcomes measures The authors analysed data on risk behaviours in both early adolescence (started smoking prior to age 14, monthly drinking and ever used illicit drugs at age 15 and sexual intercourse prior to age 16) and late adolescence (age 18–19, current smoking, excessive drinking, ever used illicit drugs and multiple sexual partners) by gender and social class. Results Drinking, illicit drug use and risky sexual behaviour (but not smoking) increased between the earlier and later cohort, especially among girls. The authors found strong associations between substance use and sexual risk behaviour during early and late adolescence, with few differences between cohorts, or by gender or social class. Adjusted ORs for associations between each substance and sexual risk behaviour were around 2.00. The only significant between-cohort difference was a stronger association between female early adolescent smoking and early sexual initiation in the later cohort. Also, relationships between illicit drug use and both early sexual initiation and multiple sexual partners in late adolescence were significantly stronger among girls than boys in the later cohort. Conclusions Despite changes in rates, relationships between adolescent risk behaviours remain strong, irrespective of gender and social class. This indicates a need for improved risk behaviour prevention in young people, perhaps through a holistic approach, that addresses the broad shared determinants of various risk behaviours.

Young people's access to tobacco, alcohol, and other drugs

Young peoples use of tobacco, alcohol, and other drugs causes concern. Early use of psychoactive substances can be harmful to health in the short term—for example, through injuries sustained or inflicted while intoxicated—and can lead to lasting patterns of consumption that increase the risk of many chronic diseases and social problems.1 2 Recent concern in the United Kingdom has focused on issues such as continued high levels of smoking by young women, binge drinking and associated antisocial behaviour by young people in general, and higher levels of cannabis use in adolescents than in most European countries.w1nnOne potential approach to reducing the use of psychoactive substances in young people is to control their availability, but public policy in this area has tended to tackle tobacco, alcohol, or illicit drugs in isolation and is not necessarily based on evidence about what works.3 We review the research evidence on availability and answer two key questions. Firstly, how easy is it for young people in the UK to obtain tobacco, alcohol, and other drugs? Secondly, do measures to control availability affect young peoples patterns of use? We concentrate on measures affecting price, tax, importation, licensing, sales practices, illicit markets, and enforcement in all of these areas. We do not deal with production, prohibition, rationing, marketing, or controls on possession or use (see bmj.com for rationale).nnThis article is based on evidence about availability synthesised from nine population surveys of people aged under 25 in various parts of the UK and on evidence synthesised from 30 reviews (including seven systematic reviews) of the effects of measures to control availability on patterns of use (specifically hazardous use by young people, where available) and health outcomes. Where review level evidence was insufficient, we included relevant primary research and data from official reports. A …

Socioeconomic differences in second-hand smoke exposure among children in Scotland after introduction of the smoke-free legislation.

Background To examine the impact of the Scottish smoke-free legislation on social inequalities in secondhand smoke (SHS) exposure among primary school children. Methods Comparison of nationally representative, cross-sectional, class-based surveys carried out in the same schools before and after legislation. Participants were 2532 primary school children (primary 7; aged around 11u2005y) surveyed in January 2006 (before legislation) and 2389 in January 2007 (after legislation). Outcome measures were salivary cotinine concentrations, self-reported family socioeconomic classification (family SEC) and family affluence scale (FAS). Results After adjusting for number of smoking parents, mean cotinine concentration varied significantly across both family SEC and FAS groups, and increased significantly stepwise from high to low family SEC/FAS. Mean cotinine fell in all family SEC/FAS groups after legislation. The relative drop in mean cotinine was equal across all family SEC/FAS groups. Adding an interaction term between survey-year and family SEC/FAS to the model showed an increase in inequalities over time, but was only significant at the 93% level using FAS and 73% using family SEC. Conclusion Inequalities in SHS exposure exist among 11-year-old children in Scotland. Smoke-free legislation has reduced exposure to SHS among all children. Although the greatest absolute reduction in cotinine is observed in the lowest SEC/FAS group, cotinine levels remain highest for this group and there is a suggestion of possible increases in inequalities, which may warrant longer-term monitoring.

Best Practice Guidelines for Monitoring Socioeconomic Inequalities in Health Status: Lessons from Scotland

CONTEXTnIn this article we present best practice guidelines for monitoring socioeconomic inequalities in health status in the general population, using routinely collected data.nnnMETHODSnFirst, we constructed a set of critical appraisal criteria to assess the utility of routinely collected outcomes for monitoring socioeconomic inequalities in population health status, using epidemiological principles to measure health status and quantify health inequalities. We then selected as case studies three recent cutting-edge reports on health inequalities from the Scottish government and assessed the extent to which each of the following outcomes met our critical appraisal criteria: natality (low birth weight rate, LBW), adult mortality (all-cause, coronary heart disease [CHD], alcohol-related, cancer, and healthy life expectancy at birth), cancer incidence, and mental health and well-being.nnnFINDINGSnThe critical appraisal criteria we derived were completeness and accuracy of reporting; reversibility and sensitivity to intervention; avoidance of reverse causation; and statistical appropriateness. Of these, the most commonly unmet criterion across the routinely collected outcomes was reversibility and sensitivity to intervention. The reasons were that most mortality events occur in later life and that the LBW rate has now become obsolete as a sole indicator of perinatal health. Other outcomes were also judged to fail other criteria, notably alcohol-related mortality after midlife (avoidance of reverse causation); all cancer sites incidence and mortality (statistical appropriateness due largely to heterogeneity of SEP gradients across different cancer sites, as well as long latency); and mental health and well-being (uncertain reversibility and sensitivity to intervention).nnnCONCLUSIONSnWe conclude that even state-of-the-art data reports on health inequalities by SEP have only limited usefulness for most health and social policymakers because they focus on routinely collected outcomes that are not very sensitive to intervention. We argue that more upstream outcome measures are required, which occur earlier in the life course, can be changed within a half decade by feasible programs and policies of proven effectiveness, accurately reflect individuals future life-course chances and health status, and are strongly patterned by SEP.