The irresistible rise of the Cohort Profile

Abstract

In recognition that cohort studies are the backbone of epidemiology, the International Journal of Epidemiology’s (IJE’s) Cohort Profile series was launched in December 2004. Then, as now, the purpose of the series was to describe a particular cohort in sufficient detail to enable readers to form collaborations, learn from each other and, where appropriate, maximize the use of existing resources through data sharing. The first cohort profiled was the British Regional Heart Study and in the Editor’s Choice heralding its appearance Shah Ebrahim wrote ‘We plan to profile a cohort study in each issue, . . . ’. Clearly, we underestimated the response. Had we stuck to that original plan, a profile accepted today would have made it into print by 2030. By the end of last year, with an inclusion rate of three profiles per issue, 4100 profiles were already in print. However, with another 50 published online or in the final stages of the submission process, it was obvious a new approach for reducing the time from acceptance to print was overdue. We decided to do two things: revise our instructions to authors and limit the number of full profiles appearing in print. The current instructions can be found at http://mc. manuscriptcentral.com/ije. Slightly more prescriptive than before, they additionally require each profile to include a Summary and a Key Messages box. Whereas the Summary should describe the rationale, methods, data and data access, the Key Messages should highlight the main scientific findings to date. Together, they should provide a succinct overview of the cohort, at the same time as enticing those interested to read the full profile. The Summary and Key Messages of every profile accepted for publication will appear in the print version of the journal. However, as for cohort profile updates, the full version of some profiles will only be published online. The Summary and Key Messages for the first of these, the QSkin Sun and Health Study, appears in this issue. Queensland in Australia has the highest rate of melanoma and skin cancer in the world, and QSkin was set up prospectively to examine the role of environment and host/genetic characteristics in their aetiology. Recruitment to QSkin closed at the end of 2011, with 23 874 women and 19 920 men aged 40–69 years enrolled from the general population of Queensland. On recruitment, 23% of these participants reported a family history of melanoma, 39% the surgical removal of one or more skin cancers and 19%410 skin cancers/ solar keratoses burnt or frozen. In addition to QSkin, this issue of IJE presents full profiles for five cohorts that cover the lifecourse from the pre-natal period, through childhood and adolescence into adulthood. The highly productive Infancia y Medio Ambiente (INMA or Environment and Childhood) Project is of particular personal interest— one of the projects I worked on in my days as a lab technician was the mother to child transfer of pesticides in breast milk. INMA is a network of birth cohorts in Spain that aims to describe exposure to environmental pollutants during pregnancy, at birth and during childhood, and to evaluate their impact and the interaction between pollutants, nutrients and genetic variants on growth, health and development. Focusing on the period from birth to adolescence, the 1987 Finnish Birth Cohort has linked data for all births in Finland in 1987 (460 000) to health registers and registers that provide information on induced abortions, criminality and state benefits. Also founded in 1987, the Ugandan–Canadian TASO-CAN Collaboration follows a nationally representative cohort of 424 000 HIV-infected patients, who initiated combination anti-retroviral therapy with the AIDS support organisation (TASO), the oldest and largest community-based provider in Africa. Findings have been reported on treatment adherence and outcomes across the lifecourse from infancy to old age and have influenced international policies on provision of therapy, for example, in conflict settings. The remaining two cohorts focus on disease risk factors in adulthood. In Australia, the PATH through life project has used data from three cohorts of people born in 1937–41, 1956–60 and 1975– 79 to identify risk factors for the common mental disorders. It has also examined cognitive development, the transition to cognitive impairment and gene–environment interactions in relation to mental health outcomes, and undertaken brain imaging in participants aged460 years. Finally, the Tromso study in Northern Norway, set up to examine risk factors for cardiovascular disease, includes data from440 000 participants in six surveys between 1974 and 2008. The cohort has produced a wealth of innovative findings, an example of Published by Oxford University Press on behalf of the International Epidemiological Association