Tag Archives: Peter Chilton

Breastfeeding and SIDS

Over the years many studies have shown an association between breastfeeding and decreased risk of sudden infant death syndrome (SIDS), with a previous meta-analysis showing an adjusted odds ratio of 0.55 (95% CI 0.44-0.69), which increased to 0.27 (95% CI 0.24-0.31) with exclusive breastfeeding.[1] However, it has been difficult to identify just how long breastfeeding needs to continue to realise this benefit. This is because duration of breastfeeding has not been correlated with reduction in risk. As a follow-up to their original meta-analysis, Thompson and colleagues worked in cooperation with the authors of the included studies to obtain individual-level data.[2] They were able to glean information on duration of breastfeeding so that the association between duration and effect could be examined. In total 9,104 infants were analysed from eight case-control studies. Although analysis showed some protection against SIDS associated with any breastfeeding up to 2 months, this was not statistically significant after controlling for potential confounders. When confounders were controlled for, analysis found that any breastfeeding for at least 2 months, compared to no breastfeeding, had an adjusted odds ratio (aOR) of 0.60 (95% CI 0.44-0.82), while it was a similar aOR of 0.61 (95% CI 0.42-0.87) for exclusive breastfeeding. The aOR for any amount of breastfeeding compared to none improved with increased duration – an aOR of 0.40 (95% CI 0.26-0.63) with 4-6 months breastfeeding, and 0.36 (95% CI 0.22-0.61) with at least 6 months breastfeeding. A similar improvement was seen with at least 4 months of exclusive breastfeeding (aOR 0.46, 95% CI 0.29-0.74).

In order to lower the incidence of SIDS it is important that new mothers are encouraged to breastfeed and to continue for at least 2 months, even if they are unable to do so exclusively, as any amount of breastfeeding seems to confer more protection than none.

— Peter Chilton, Research Fellow


  1. Hauck FR, Thompson JM, Tanabe KO, Moon RY, Vennemann MM. Breastfeeding and reduced risk of sudden infant death syndrome: a meta-analysis. Pediatrics. 2011; 128(1): 103–10
  2. Thompson JMD, Tanabe K, Moon RY, Mitchell EA, McGarvey C, Tappin D, Blair PS, Hauck FR. Duration of Breastfeeding and Risk of SIDS: An Individual Participant Data Meta-analysis. Pediatrics. 2017: e20171324.

Deforestation and Diarrhoea

Contaminated water can lead to numerous diseases, including diarrhoea, a leading cause of child mortality. In a previous News Blog we discussed the importance of water contamination, and the many methods by which it can occur.[1] One such route is contaminated surface water, which has been linked to outbreaks of diarrhoea in previous studies.[2] A major factor affecting the quality of surface water is the ‘watershed condition’ – the natural land cover provided by the ecosystem, such as forests and wetlands. This ecosystem filters pollutants and pathogens from surface water supplies, and can stabilise soil, and minimise erosion and sediment loading.

Herrera and colleagues conducted an observational database study of almost 300,000 children aged under 5 from 35 countries, looking at their health, socioeconomic factors (such as mother’s education, household wealth, access to improved sanitation and water sources), climate (temperature and precipitation) and watershed condition.[3] Watershed condition was measured by estimating the percentage of water that was affected by people and livestock or tree cover upstream from the household.

They found that high tree cover upstream of the child’s household was associated with a lower probability of diarrhoea (odds ratio less than 1, but not specified). This was significant only for rural households, however, not urban. In rural communities it is estimated that only 33% of households obtain their water from piped sources (compared to 79% in urban areas), and 93% of people who use surface water as their main water source live in rural areas.

The authors used a model to estimate that increasing tree cover upstream by 30% would have a similar effect to improving sanitation (an estimated 4% reduction in probability of diarrhoea from baseline). It would, however, not have as great an impact as improving the water source (7% reduction), wealth (12% reduction) or education of the households (13% reduction). It seems that, under certain conditions, conservation strategies that ensure that tree cover is high could serve as effective investments in public health.

— Peter Chilton, Research Fellow


  1. Lilford RJ. A Secondary Sanitary Revolution? What About the First One? NIHR CLAHRC West Midlands News Blog. September 1, 2017.
  2. Bessong, P., Odiyo, J., Musekene, J. & Tessema, A. Spatial distribution of diarrhoea and microbial quality of domestic water during an outbreak of diarrhoea in the Tshikuwi community in Venda, South Africa. J Health Popul Nutr 2009; 27: 652-9.
  3. Herrera D, Ellis A, Fisher B, et al. Upstream watershed condition predicts rural children’s health across 35 developing countries. Nature Comm 2017; 8: 811.

How Many Mutations for Cancer?

During our lifetime our somatic cells (non-reproductive cells) constantly accumulate mutations – in some cases these mutations lead to uncontrolled proliferation and allow the cells to invade other tissues and spread to other organs – i.e. become cancerous. Most of the mutations in cancerous cells are unimportant – it is only a few that are ‘drivers’ of cancer and dictate the way the cell behaves. However, we do not know how many mutations are actually required to cause cancer, or whether this number varies across cancer types.

Researchers working for the Wellcome Trust looked at over 7,500 tumours of 29 cancer types using methods adapted from molecular evolution to see which mutations were more common in cancerous than in non-cancerous cells.[1] They found that, on average, cancerous cells have around four coding substitutions (where a DNA nucleobase is exchanged for another, such as switching from adenine to guanine) that are ‘driver mutations’. This ranged from around one mutation per tumour in thyroid and testicular cancer, four in breast and liver cancer, to more than ten in endometrial and colorectal cancer. Of these ‘driver mutations’ around half occur in cancer genes that have yet to be discovered.

In the long-term these findings could help advance the development of precision cancer treatment, allowing drugs to be specifically targeted at the appropriate mutation(s).

— Peter Chilton, Research Fellow


  1. Matrincorena I, Raine KM, Gerstung M, Dawson KJ, Haase K, Van Loo P, Davies H, Stratton MR, Campbell PJ. Universal Patterns of Selection in Cancer and Somatic Tissues. Cell. 2017.

Autism and Allergies

The prevalence of autism spectrum disorder (ASD) is increasing, with the US Centers for Disease Control and Prevention estimating that 1 in 68 people have the disorder. While there is no single known cause of ASD, research has suggested that the immune system may have a role, and that activation of the maternal immune response during pregnancy may increase the risk of ASD developing in the unborn child. A recent paper in Nature investigated associations between the maternal immune activation (MIA) and the severity of ASD symptoms in their child.[1]

The authors analysed an existing cohort of 220 children diagnosed with autism spectrum disorder (ASD) and found that the children whose mothers had a history of allergies and/or asthma had significantly higher scores on the social responsiveness scale (SRS) (p=0.016), compared to those whose mothers did not. The SRS measures social interaction, language, and repetitive/restricted behaviours and interests in the child; a higher score is suggestive of a greater degree of social impairment symptoms. The association was not seen when looking at autoimmune conditions, but many of the mothers were diagnosed with autoimmune problems post-pregnancy, which may have affected the findings.

Although no causal relationship was shown, the study does suggest that the immune system may have a role in ASD.

— Peter Chilton, Research Fellow


  1. Patel S, Masi A, Dale RC, Whitehouse AJO, Pokorski I, Alvares GA, Hickie IB, Breen E, Guastella AJ. Social impairments in autism spectrum disorder are related to maternal immune history profile. Mol Psychiatry. 2017.

Sniffing Out Trouble

The scent of freshly baked bread; the smell of a recently-mown lawn on a summer’s breeze; the aroma of an open bottle of wine – people often take particular delight in smell. But as we get older our olfactory function starts to decline. Interestingly, previous research has shown that adults with dementia have more difficulty distinguishing smells, compared to adults without dementia. However, we do not know whether this olfactory dysfunction is predictive of subsequent dementia.

A longitudinal study of 2,906 US adults aged 57-85 measured their ability to identify five odours (rose, leather, orange, fish and peppermint) using a validated test, then looked at the incidence of dementia five years later.[1] They found that adults who had difficulty identifying the smells at baseline were more than twice as likely to have developed dementia by the five year follow up (odds ratio = 2.13, 95% CI 1.32-3.43). This was after controlling for age, sex, race and ethnicity, education, comorbidities, and cognition at baseline. Further, more errors in identification was associated with greater probability of dementia diagnosis (p=0.04). Unfortunately, as the authors admit, they did not control for confounders already associated with olfactory function, such as smoking or depression.

It is hoped that using such an odour identification test will be an efficient and cost-effective addition to current examinations that assess an individual’s risk of dementia, thereby allowing early interventions and give individuals more time to plan for their future. It may also be a useful tool for early diagnosis of Parkinson’s disease, which is also associated with olfactory dysfunction.

— Peter Chilton, Research Fellow


  1. Adams DR, Kern DW, Wroblewski KE, McClintock MK, Dale W, Pinto JM. Olfactory Dysfunction Predicts Subsequent Dementia in Older U.S. Adults. J Am Geriatr Soc. 2017.

Another Study on the Hazards of American Football

Head impacts seem to be a common occurrence in American Football, with studies of youth players suggesting they experience around 240-252 impacts per season.[1] [2] In the previous News Blog we looked at research on brain injury in ex-American Football players, which found widespread chronic traumatic encephalopathy.[3] Now a cross-sectional study by Alosco, et al. has looked at the impact playing from an early age has on behaviour, mood and cognition.[4] The authors assessed 214 former amateur and professional football players (who hadn’t played any other contact sport) on a number of psychiatric tests. Multivariate regression analysis showed that those who had begun playing before the age of 12 had at least twice the risk of significant impairments in behavioural regulation, apathy and executive function, and three times the risk for clinically elevated depression, compared with those who were began playing when they were 12 or older. These effects were not linked to age, education or even how long the individual played football for. There were also no differences in the level of play, i.e. those who played professional fared similar to those who only played at high school-level. The authors hypothesise that 12 years old is a critical time for key neurodevelopmental milestones that occur within the hippocampus and amygdala (where clinical functions such as emotion regulation and behaviour are modulated).

— Peter Chilton, Research Fellow


  1. Munce TA, Dorman JC, Thompson PA, Valentine VD, Bergeron MF. Head impact exposure and neurologic function of youth football players. Med Sci Sports Exerc. 2015; 47: 1567–76.
  2. Cobb BR, Urban JE, Davenport EM, Rowson S, Duma SM, Maldjian JA et al. Head impact exposure in youth football: elementary school ages 9-12 years and the effect of practice structure. Ann Biomed Eng. 2013; 41: 246373.
  3. Lilford RJ. Two Hundred and Two Ex-(American) Footballers’ Brains Analysed After Death – This You Must Read. NIHR CLAHRC West Midlands News Blog. 15 September 2017.
  4. Alosco ML, Kasimis AB, Stamm JM, et al. Age of first exposure to American football and long-term neuropsychiatric and cognitive outcomes. Transl Psychiatry. 2017; 7: e1236.

Alternative Therapies for Cancer

We often read of cancer patients who forgo or delay traditional conventional options, such as chemotherapy, and instead opt for alternative therapies, such as spiritual healing or herbal remedies given by non-medical personnel. Unfortunately this can have serious survival implications for the patient – in many cases the treatment fails to stop the cancer. However, there is a paucity of actual clinical evidence on the use and effectiveness of alternative therapies. Step in Johnson and colleagues who examined the United States Cancer Database to compare the survival outcomes of patients who underwent alternative therapies with those who received conventional therapies for four cancer types (breast, prostate, lung and colorectal).[1] Although rare, they found 281 patients who had chosen alternative therapies exclusive of any other treatment – these patients were more likely to be younger, female, have a lower comorbidity score, higher income, higher education, and a more advanced cancer stage. When matched with patients who received conventional treatments (on cancer type, age, clinical stage, etc.), they found that alternative therapies were associated with significantly lower five-year survival overall – 78.3% of patients who underwent conventional therapies survived, compared to 54.7% of those who had alternative therapies only (hazard ratio 2.21, 95% CI 1.72-2.83). When looked at by cancer type increased hazard ratios were found for breast (HR 5.68, 95% CI 3.22-10.04), lung (HR 2.17, 95% CI 1.42-3.32) and colorectal cancer (HR 4.57, 1.66-12.61), but there was no significant difference for prostate cancer (HR1.68, 95% CI 0.68-4.17) – the authors suggest this may be because of the long natural history of prostate cancer and the short follow-up of the study.

By itself, undergoing alternative therapies isn’t likely to be harmful, but it should be taken in combination with conventional therapy, and health practitioners need to ensure that patients are fully aware of the impact of their decisions regarding cancer treatment.

— Peter Chilton, Research Fellow

  1. Johnson SB, Park HS, Gross CP, Yu JB. Use of Alternative Medicine for Cancer and Its Impact on Survival. J Natl Cancer Inst. 2017.

Improving Access to Fresh Food in Low-Income Areas

In a previous News Blog we looked at a paper that found an association between adherence to the Mediterranean diet (i.e. high consumption of fruit, vegetables, and legumes) and reduction in cardiovascular disease risk.[1] So, it can be argued, that for those in low-income areas there is a need to improve their access to fresh fruit and vegetables. But how best to achieve this? Breck and colleagues, on behalf of the CDC, looked at one possibility in a cross-sectional survey analysis.[2]

Previously, the city of New York had attempted to address the issue by granting new licenses for mobile fruit and vegetable carts in those neighbourhoods with poor availability of fresh food. However, only some of the carts (27%) had the capacity to accept the Supplemental Nutrition Assistance Program (SNAP) benefits (a federal aid program to provide food-purchasing assistance) through use of Electronic Benefit Transfer (EBT) machines.

The authors conducted a survey analysis of 779 adults shopping at four carts in the Bronx neighbourhood of New York over several time periods. After controlling for cofounders, they found that those shoppers who were able to pay using their SNAP benefits purchased significantly (p<0.001) more fruit and vegetables (an average of 5.4 more cup equivalents), than those who were only able to pay with cash. While there are promising results from providing consumers with more ways to pay, there are challenges that could prevent widespread roll out of EBT, chiefly the high initial, monthly, and transaction fees that the cart vendors need to pay. Even when provided with financial support, less than one-third of carts were equipped with EBT machines at the time of this study. Although the study has a number of limitations that means causal inferences cannot be drawn, it can be seen as a possible avenue for future research.

— Peter Chilton, Research Fellow


  1. Chilton P. Diet and Socioeconomic Status. 18 August 2017.
  2. Breck A, Kiszko K, Martinez O, Abrams C, Elbel B. Could EBT Machines Increase Fruit and Vegetable Purchases at New York City Green Carts? Prev Chronic Dis. 2017; 170104.

Association Between Cigarette Price and Infant Mortality

In an effort to reduce smoking rates governments often increase the taxation levied on cigarettes. Previous research has shown that this is an effective strategy, including improvements in child health outcomes. However, tobacco companies often use differential pricing strategies to move the increased taxation on to their premium cigarettes. This lessens the effectiveness of increased taxes as it allows people to switch to the cheaper cigarettes instead. Researchers from Imperial College London set out to assess any associations between price rises, differential pricing (using data on the minimum and median cigarette prices) and infant mortality across 23 European countries.[1] This longitudinal study looked at more than 53.7m live births over a period of ten years. During this time the authors found that a median increase of €1 per pack of cigarettes was associated with 0.23 fewer deaths per 1000 live births in the year of the price hike (95% CI, -0.37 to -0.09), and a decline of 0.16 deaths per 1000 live births in the subsequent year (95% CI, -0.30 to -0.03). Using a counterfactual scenario, the authors estimated that, overall, cigarette price increases were associated with 9,208 fewer infant deaths (i.e. if cigarette prices had remained unchanged then there would have been 9,208 more deaths). Analysis of the price differentials showed that a 10% increase in the differential between the minimum and median priced cigarettes was associated with 0.07 more deaths per 1,000 live births the following year. Further, had there been no cost differential, they estimated that 3,195 infant deaths could have been avoided.

So, while increasing cigarette taxation can have a positive effect, there needs to be more of an effort to try to eliminate budget cigarettes. This is especially true in low-income countries where price differentials tend to be significantly higher than in high-income countries.

— Peter Chilton, Research Fellow


  1. Filippidis FT, Laverty AA, Hone T, Been JV, Millett C. Association of Cigarette Price Differentials With Infant Mortality in 23 European Union Countries. JAMA Pediatr. 2017.

Vaccination Savings

We know that vaccination is one of the most cost-effective interventions in terms of improving public health, but it can only be at its most effective if it is encouraged and supported by policy-makers and government officials. A recent paper in the Bulletin of the World Health Organization looked at the potential economic benefits of providing ten different vaccinations in 73 low- and middle-income countries.[1] These included vaccinations against hepatitis B, measles, rubella, and yellow fever. The authors found that if vaccinations were given routinely between 2001 and 2020, not only would 20 million children avoid death, but there would also be an estimated saving of $347 billion. This figure is predominantly made up of lifelong productivity gains from deaths avoided ($330 billion), but also from disabilities avoided ($9.4 billion), treatment costs ($4.5 billion), transport costs ($0.5 billion), and lost caregiver wages ($0.9 billion). Further they estimate that $820 billion would be saved from the broader economic and social value of vaccinations. The biggest contributor to these estimates was vaccination against measles, followed by H. influenza type b, S. pneumoniae, and hepatitis B.

— Peter Chilton, Research Fellow


  1. Ozawa S, Clark S, Portnoy A, et al. Estimated economic impact of vaccinations in 73 low- and middle-income countries, 2001–2020. Bull World Health Organ. 2017