David K. Humphreys

Associations between active commuting and physical and mental wellbeing

Objective To examine whether a relationship exists between active commuting and physical and mental wellbeing. Method In 2009, cross-sectional postal questionnaire data were collected from a sample of working adults (aged 16 and over) in the Commuting and Health in Cambridge study. Travel behaviour and physical activity were ascertained using the Recent Physical Activity Questionnaire (RPAQ) and a seven-day travel-to-work recall instrument from which weekly time spent in active commuting (walking and cycling) was derived. Physical and mental wellbeing were assessed using the Medical Outcomes Study Short Form survey (SF-8). Associations were tested using multivariable linear regression. Results An association was observed between physical wellbeing (PCS-8) score and time spent in active commuting after adjustment for other physical activity (adjusted regression coefficients 0.48, 0.79 and 1.21 for 30–149 min/week, 150–224 min/week and ≥ 225 min/week respectively versus < 30 min/week, p = 0.01 for trend; n = 989). No such relationship was found for mental wellbeing (MCS-8) (p = 0.52). Conclusion Greater time spent actively commuting is associated with higher levels of physical wellbeing. Longitudinal studies should examine the contribution of changing levels of active commuting and other forms of physical activity to overall health and wellbeing.

Domestic Violence Perpetrator Programs in Europe, Part II: A Systematic Review of the State of Evidence

In Part II of this article, we present the results of a systematic review of European evidence on the effectiveness of domestic violence perpetrator programs. After searching through 10,446 titles, we discovered only 12 studies that evaluated the effectiveness of a perpetrator program in some systematic manner. The studies applied treatment to a total of 1,586 domestic violence perpetrators, and the sample sizes ranged from 9 to 322. Although the evaluations showed various positive effects after treatment, methodological problems relating to the evaluation designs do not allow attribution of these findings to the programs. Overall, the methodological quality of the evaluations is insufficient to derive firm conclusions and estimate an effect size. Accordingly, one cannot claim that one programmatic approach is superior to another. Evaluation of domestic violence perpetrator treatment in Europe must be improved and programs should become more tailored to the characteristics of the participants.

Evaluating the Impact of Florida's "Stand Your Ground" Self-defense Law on Homicide and Suicide by Firearm: An Interrupted Time Series Study.

Importance In 2005, Florida amended its self-defense laws to provide legal immunity to individuals using lethal force in self-defense. The enactment of “stand your ground” laws in the United States has been controversial and their effect on rates of homicide and homicide by firearm is uncertain. Objective To estimate the impact of Florida’s stand your ground law on rates of homicide and homicide by firearm. Design, Setting, and Participants Using an interrupted time series design, we analyzed monthly rates of homicide and homicide by firearm in Florida between 1999 and 2014. Data were collected from the Wide-ranging Online Data for Epidemiologic Research (WONDER) web portal at the Centers for Disease Control and Prevention. We used seasonally adjusted segmented Poisson regression models to assess whether the onset of the law was associated with changes in the underlying trends for homicide and homicide by firearm in Florida. We also assessed the association using comparison states without stand your ground laws (New York, New Jersey, Ohio, and Virginia) and control outcomes (all suicides and suicides by firearm in Florida). October 1, 2005, the effective date of the law, was used to define homicides before and after the change. Main Outcomes and Measures Monthly rates of homicide, firearm-related homicide, suicide, and suicide by firearm in Florida and the 4 comparison states. Results Prior to the stand your ground law, the mean monthly homicide rate in Florida was 0.49 deaths per 100 000 (mean monthly count, 81.93), and the rate of homicide by firearm was 0.29 deaths per 100 000 (mean monthly count, 49.06). Both rates had an underlying trend of 0.1% decrease per month. After accounting for underlying trends, these results estimate that after the law took effect there was an abrupt and sustained increase in the monthly homicide rate of 24.4% (relative risk [RR], 1.24; 95%CI, 1.16-1.33) and in the rate of homicide by firearm of 31.6% (RR, 1.32; 95% CI, 1.21-1.44). No evidence of change was found in the analyses of comparison states for either homicide (RR, 1.06; 95% CI, 0.98-1.13) or homicide by firearm (RR, 1.08; 95% CI, 0.99-1.17). Furthermore, no changes were observed in control outcomes such as suicide (RR, 0.99; 95% CI, 0.94-1.05) and suicide by firearm (RR, 0.98; 95% CI, 0.91-1.06) in Florida between 2005 and 2014. Conclusions and Relevance The implementation of Florida’s stand your ground self-defense law was associated with a significant increase in homicides and homicides by firearm but no change in rates of suicide or suicide by firearm.

Evaluating the impact of flexible alcohol trading hours on violence: an interrupted time series analysis

Background On November 24th 2005, the Government of England and Wales removed regulatory restrictions on the times at which licensed premises could sell alcohol. This study tests availability theory by treating the implementation of Licensing Act (2003) as a natural experiment in alcohol policy. Methods An interrupted time series design was employed to estimate the Act’s immediate and delayed impact on violence in the City of Manchester (Population 464,200). We collected police recorded rates of violence, robbery, and total crime between the 1st of February 2004 and the 31st of December 2007. Events were aggregated by week, yielding a total of 204 observations (95 pre-, and 109 post-intervention). Secondary analysis examined changes in daily patterns of violence. Pre- and post-intervention events were separated into four three-hour segments 18∶00–20∶59, 21∶00–23.59, 00∶00–02∶59, 03∶00–05∶59. Results Analysis found no evidence that the Licensing Act (2003) affected the overall volume of violence. However, analyses of night-time violence found a gradual and permanent shift of weekend violence into later parts of the night. The results estimated an initial increase of 27.5% between 03∶00 to 06∶00 (ω = 0.2433, 95% CI = 0.06, 0.42), which increased to 36% by the end of the study period (δ = −0.897, 95% CI = −1.02, −0.77). Conclusions This study found no evidence that a national policy increasing the physical availability of alcohol affected the overall volume of violence. There was, however, evidence suggesting that the policy may be associated with changes to patterns of violence in the early morning (3 a.m. to 6 a.m.).

Changing the environment to improve population health: a framework for considering exposure in natural experimental studies

There is renewed optimism regarding the use of natural experimental studies to generate evidence as to the effectiveness of population health interventions. Natural experimental studies capitalise on environmental and policy events that alter exposure to certain social, economic or environmental factors that influence health. Natural experimental studies can be useful for examining the impact of changes to ‘upstream’ determinants, which may not be amenable to controlled experiments. However, while natural experiments provide opportunities to generate evidence, they often present certain conceptual and methodological obstacles. Population health interventions that alter the physical or social environment are usually administered broadly across populations and communities. The breadth of these interventions means that variation in exposure, uptake and impact may be complex. Yet many evaluations of natural experiments focus narrowly on identifying suitable ‘exposed’ and ‘unexposed’ populations for comparison. In this paper, we discuss conceptual and analytical issues relating to defining and measuring exposure to interventions in this context, including how recent advances in technology may enable researchers to better understand the nature of population exposure to changes in the built environment. We argue that when it is unclear whether populations are exposed to an intervention, it may be advantageous to supplement traditional impact assessments with observational approaches that investigate differing levels of exposure. We suggest that an improved understanding of changes in exposure will assist the investigation of the impact of complex natural experiments in population health.

Synthesising evidence for equity impacts of population-based physical activity interventions: a pilot study

BackgroundThis study applied an equity lens to existing research to investigate what is known about the impact of population-level physical activity interventions on social inequalities.MethodsWe performed a pilot systematic review to assess the availability of information on the social distribution of intervention effects, the targeting or allocation of interventions, and the baseline characteristics of participants. This comprised (i) a rapid review of systematic reviews and (ii) a review and synthesis of a sample of primary studies included in the eligible systematic reviews.ResultsWe found 19 systematic reviews of environmental and policy interventions. Relatively few of these (26%, n=5) were prospectively designed to examine effects on inequalities, and none were able to fully synthesise evidence of distributional effects. Over 40% of primary studies reported subgroup intervention effects; 18% reported socio-demographic interaction effects. Studies most often compared effectiveness by gender, followed by age, ethnicity, and socio-economic status. For gender, effects appeared to be evenly distributed overall, although heterogeneity in gradients between studies suggested that some interventions affect males and females differently.ConclusionsOur findings suggest that it is feasible to generate better evidence about how public health interventions may affect health inequalities using existing data and innovative methods of research synthesis.

Disclosure of Financial Conflicts of Interests in Interventions to Improve Child Psychosocial Health: A Cross-Sectional Study

Academic journals increasingly request a full disclosure of financial conflict of interest (CoI). The Committee for Publication Ethics provides editors with guidance about the course of action in the case of suspected non-disclosure. No prior study has examined the extent to which journal articles on psychosocial interventions disclose CoI, and how journal editors process requests to examine suspected undisclosed CoI. Four internationally disseminated psychosocial interventions were examined. 136 articles related to an intervention, co-authored by intervention developers and published in health sciences journals were retrieved as requiring a CoI statement. Two editors refused consent to be included in the study. COI disclosures and editor responses were coded for 134 articles. Overall, 92/134 (71%) of all articles were found to have absent, incomplete or partly misleading CoI disclosures. Disclosure rates for the four programs varied significantly between 11% and 73%. Journal editors were contacted about 92 published articles with no CoI disclosure or a disclosure that was considered problematic. In 65/92 (71%) of all cases the editors published an ‘erratum’ or ‘corrigendum’. In 16 of these cases the journal had mishandled a submitted disclosure. The most frequent reason for non-publication of an erratum was that the journal had no disclosure policy at the time of the publication (16 cases). Consumers of research on psychosocial interventions published in peer-reviewed journals cannot currently assume that CoI disclosures are adequate and complete. More efforts are needed to achieve transparency.

Alcohol licensing data: Why is it an underused resource in public health?

Alcohol-related harm is related to alcohol availability. Due to complex regulatory and environmental factors, alcohol availability varies spatially. However, the extent of this variation is largely unknown in the UK, despite its potential influence on patterns of alcohol-related harm. We investigate why administrative data is underused in the study of alcohol-related harm in the UK. We found that local authorities routinely collect a rich supply of licensing data. However, this information is stored in databases that are sometimes difficult to access. With greater coordination between researchers and practitioners, this data can be used to fulfil its primary administrative purpose and also contribute to understanding and prevention of alcohol-related health and social problems.

Effects of new urban motorway infrastructure on road traffic accidents in the local area: a retrospective longitudinal study in Scotland.

Background The M74 motorway extension, Glasgow, opened in June 2011. One justification for construction was an expectation that it would reduce road traffic accidents (RTAs) on local non-motorway roads. This study evaluated the impact of the extension on the number of RTAs, stratifying by accident severity. Methods Data for the period 1997–2014 were extracted from a UK database of reported RTAs involving a personal injury. RTA severity was defined by the level of injury: minor, severe or fatal. RTAs were assigned to (1) the local area surrounding the motorway extension, (2) a comparator area surrounding an existing motorway or (3) a control area elsewhere in the conurbation. Interrupted time-series regression with autoregressive integrated moving average (ARIMA) errors was used to determine longitudinal between-area differences in change in the number of RTAs, which might indicate an intervention effect. Results Glasgow and surrounding local authorities saw a 50.6% reduction in annual RTAs (n: 5901 to 2914) between 1997 and 2014. In the intervention area, the number of recorded RTAs decreased by 50.7% (n: 758 to 374), and that of fatal/severe RTAs by 57.4% (n: 129 to 55), with similar reductions in the comparator/control areas. The interrupted time-series analysis showed no significant between-area differences in temporal trends. The reduction of pedestrian casualties was attenuated in the intervention area relative to Glasgow and surrounding authorities. Conclusions Reduction in RTAs was not associated with the motorway extension. Our findings suggest that in planning future investment, it should not be taken for granted that new road infrastructure alone will reduce RTAs in local areas. Urbanisation is proceeding rapidly worldwide, and evidence of infrastructure changes is lacking; this novel study provides important findings for future developments.

Questioning the application of risk of bias tools in appraising evidence from natural experimental studies: critical reflections on Benton et al., IJBNPA 2016

We recently read the article by Benton et al. which reviewed risk of bias in natural experimental studies investigating the impact of the built environment on physical activity (Benton et al., 2016; Int J Behav Nutr Phys Act 13:107). As a technical exercise in assessing risk of bias to understand study quality, we found the results of this study both interesting and potentially useful. However, it prompted a number of concerns with the use of risk of bias tools for assessing the quality of evidence from studies exploiting natural experiments. As we discuss in this commentary, the rigid application of such tools could have adverse effects on the uptake and use of natural experiments in population health research and practice.