Data collection and management for research studies

Randomized clinical trials in infancy: methodologic issues

Randomized clinical trials of early nutritional interventions in infants are necessary to establish safety and efficacy of supplementation of infant formulas with LCPUFAS for term and preterm infants. Such trials pose significant methodologic difficulties when applied to infants because of the rapidly changing development of the infant's central nervous system and its interdependence with multiple environmental factors. Current assessments of infant cognitive development in the first year of life lack stability and predictive relationships to later outcomes. Thus, intervention trials need to extend beyond the first two years of life. Small sample sizes, high attrition rates, and lack of attention to confounding variables known to be related to child outcomes are additional problems in the majority of studies to date, especially for preterm populations. Attention to selection and attrition biases and the roles of mediating and moderating factors in affecting intervention effects are also necessary to determine the benefits vs risks of LCPUFA supplementation of infant formula.

Methodological issues in randomized controlled trials

There is increasing emphasis on the need to practise evidence-based medicine and the strongest evidence comes from well designed and well-conducted randomized controlled trials. Every component is important for the success of a clinical trial; if the design or sample size is inappropriate, then the results of the study will be unreliable, however well the study is conducted. Conversely a well-designed study may founder because of poor outcome measurement or unacceptably high subject loss. The advantages of a well-designed trial apply equally to studies with short term outcomes and to those requiring long-term follow up. This paper therefore focuses on general methodological issues with a discussion, where appropriate, of the special considerations associated with long-term follow-up. This emphasis is motivated by the belief that a trial with methodological weaknesses is both a waste of resources and unethical. Anyone planning to undertake a randomized controlled trial should consult a more comprehensive text [1-4]. Here, some selected issues are highlighted with the choice of topics reflecting the experience and interests of the authors.