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Rigour and validity of research findings – a tale of two controversies

Authors of articles published in this Journal know that papers are submitted to peer review and, almost always, the paper requires revision before publication. While peer review has problems, it does involve academic peers evaluating research reports and reviews, with authors then having the opportunity for appropriate revision to increase scientific validity, as well as improving the comprehensibility of a paper. Peer review is, therefore, a significant step in the research process. For this reason, reviewers for individual papers are selected on the basis of expertise in both the content area and in the methods the authors have used. Articles are submitted for publication for different reasons. Research produces evidence that underpins practice and policy decisions, but can also point to the need for further studies, and may also provoke debate. Results may also be communicated to the public for health promotion purposes, either directly or through media outlets, and as most reporters are not trained in epidemiology or health research, it is up to the researchers and journals to provide clear and defensible ‘take-home messages’. Two examples from the 1990s show how problems arose when questionable research results changed public practice: intramuscular vitamin K at birth and measles vaccination. They provide a cautionary tale that illustrates the issues we take into account when judging the rigour and validity of research findings. A 1970s cohort study had suggested of an association between Vitamin K administration and childhood cancer. Golding and colleagues conducted a case control study that compared the birth records of 195 children with cancer with 558 unmatched controls. They showed a significant association between childhood cancer and the receipt of intramuscular (but not oral) vitamin K at birth. Vitamin K is routinely provided to newborn infants to prevent haemolytic disease of the newborn (HDN) and is an important perinatal public health intervention. The authors were very circumspect, with an extensive discussion of bias and confounding, emphasising that the benefits of preventing potentially fatal haemorrhagic disease must be weighed against the costs, but arguing that oral rather than injected Vitamin K conveyed the benefits for HDN prevention without the risk of cancer. The paper sparked considerable press interest and anxiety among the general public and some countries (such as The Netherlands) adopted the suggested policy. The policy was not adopted in Australia, largely because of availability problems, but the issue provoked much policy analysis and intense scientific debate. Subsequent studies attempting to replicate these results, as well as meta-analysis, concluded that injected Vitamin K does not lead to childhood cancer. Many countries, including Australia, have issued specific guidelines for perinatal Vitamin K use and administration. Vitamin K injections remain an important intervention to prevent haemolytic disease of the newborn in the labour ward. Apart from the initial concern roused among policy makers and the public, this example illustrates the way in which scientific publication generates debate and identifies where subsequent studies are needed to verify or refute important but tentative early results. The question is how we can be sure that uncertain scientific findings are not interpreted with more confidence than the study deserves. In the next example, this process ran aground. In 1998, a British team published an early report in The Lancet in which they raised serious concerns about the measles component of the MMR (measles, mumps and rubella) vaccine based on a sample of 12 children, most of whom who had recently been given MMR vaccine. The methods section of the paper is scanty in its description of recruitment processes; the cases were eventually shown to be opportunistic at best, and the method by which the 12 cases were apparently matched to 14 controls remains unclear. The alarming results associated MMR vaccination with autism and Crohn’s disease. The main results are as follows: “Onset of behavioural symptoms was associated, by the parents, with measles, mumps, and rubella vaccination in eight of the 12 children, with measles infection in one child, and otitis media in another. All 12 children had intestinal abnormalities, ranging from lymphoid nodular hyperplasia to aphthoid ulceration. Histology showed patchy chronic inflammation in the colon in 11 children and reactive ileal lymphoid hyperplasia in seven, but no granulomas. Behavioural disorders included autism (nine), disintegrative psychosis (one), and possible postviral or vaccinal encephalitis (two). There were no focal neurological abnormalities and MRI and EEG tests were normal. Abnormal laboratory results were significantly raised urinary methylmalonic acid compared with age-matched controls (p=0.003), low haemoglobin in four children, and a low serum IgA in four children.”