” “Research highlights” is a weekly round-up of research papers appearing in the print BMJ. We start off with this week’s research questions, before providing more detail on some individual research papers and accompanying articles.

• Does a high intake of dietary fibre or whole grains reduce the risk of developing colorectal cancer?
• Does integrated care for chronic physical diseases and depression improve disability and quality of life outcomes?
• Can an additional review based on reporting guidelines, such as STROBE and CONSORT, improve the quality of manuscripts reviewed by a biomedical journal?
• Can an accurate formula be developed to help allocate NHS funds to general practices in England for commissioning hospital care, based on the health needs of individuals in each practice?

Fibre and colorectal disease: are all fibres equal?

It’s difficult to give patients specific and accurate advice about what to eat or avoid in an evidence based way. Randomised controlled trials of foods are problematic—it’s hard to randomise people to a specific diet, let alone follow them up until they manifest major medical diagnoses years later. So researchers are left with observational research, and trying to dampen down the statistical noise from the numerous other lifestyle choices people make, to better characterise the links between diet and disease, such as fibre and colorectal cancer.

Recent, large scale studies suggest a link between fibre and colorectal cancer, and there are biological theories to support the possibility that this link is causal. But, is there a dose response? Are all fibres equal? Is it all about bulk, or are there other properties of specific fibrous foods—such as fruit and vegetables or wholegrains—that are important? Dagfinn Aune and colleagues have done a systematic review and meta-analysis to investigate.

The authors find a modest link, with the usual cautions that these data are observational, and that by combining studies the potential for confounding has not been reduced. It is a strength that the authors have looked at the source of fibre and not just total fibre from all foods, write Anne Tjønneland and Anja Olsen in a linked editorial. It seems whole grains, in particular, are associated with lowered risk of colorectal cancer; they are already known to be of benefit in cardiovascular disease. For doctors counselling patients, this latest association adds to the list of conditions that whole grains, such as oats and other cereals, might help to prevent.

Co-targeting physical and mental illness for healthy ageing

As people live longer and the population of older people living with chronic diseases grows, so too does the proportion of older people with comorbid depression, says editorialist Dilip V Jeste. Coexisting mental and physical problems may add up to more than the sum of their parts, and studies show that treatment for depression reduces disability in patients with arthritis, diabetes, heart disease, and chronic pain. But the potential of such treatment to improve the lives of chronically ill people as they age is often overlooked. Previous trials of treatment to control diabetes and cardiovascular risk factors suggest that although these treatments can prevent major events in the long term, they don’t seem to improve functioning and quality of life—outcomes that might be improved by treatment for depression.

Michael Von Korff and colleagues aimed to harness the power of simultaneous treatment for mental and chronic physical illness, to enhance “successful ageing.” In a randomised controlled trial, they investigated an integrated care programme in 14 US primary care clinics. The 12 month intervention, called TEAMcare, combined a treat to target programme for diabetes and coronary heart disease with collaborative care for depression. They found that this approach reduced social role disability—the extent to which health interfered with work, family life, and social life—and improved global quality of life in the middle aged and older people who participated. However, they report, the trial was underpowered to evaluate disability outcomes, so the small observed improvement in functioning should be interpreted in the light of other studies.

Perinatal and maternal outcomes by planned place of birth for women with low risk pregnancies
Results of a study by the Birthplace in England Collaborative Group support a policy of offering women with low risk pregnancies a choice of birth setting—at home or in a midwifery unit (doi:10.1136/bmj.d7400).

Overdiagnosis from non-progressive cancer detected by screening mammography
Arnaud Seigneurin and colleagues conducted a modelling study and found that overdiagnosis for invasive cancers was smaller than expected in a French population offered organised and individual screening.