title: Importance of adequate sample sizes in fatty acid intervention trials.
abstract: Randomised controlled trials are the ideal way to assess the effects of interventions. Small trials are useful for generating pilot data to determine samples sizes for larger trials, but can produce unreliable or biased results if they are considered in their own right. We investigate the impact of small sample sizes due to either inadequate recruitment targets or high attrition rates on the results of fatty acid intervention trials. Data from our large trial of DHA supplementation during pregnancy with minimal attrition are used for illustration. Our findings demonstrate that recruiting fewer participants or neglecting to follow up difficult participants can lead to substantially different results and alter conclusions about the effectiveness of the intervention. Developing strategies for overcoming these inadequacies should be a top priority in fatty acid intervention trials.
authors.affiliation: Women׳s and Children׳s Health Research Institute, The University of Adelaide, Australia; School of Public Health, The University of Adelaide, Australia. Electronic address: lisa.yelland@adelaide.edu.au.
authors.forename: Lisa N
authors.initials: LN
authors.lastname: Yelland
authors.affiliation: Women׳s and Children׳s Health Research Institute, The University of Adelaide, Australia; South Australian Health and Medical Research Institute, Australia; School of Paediatrics and Reproductive Health, The University of Adelaide, Australia.
authors.forename: Maria
authors.initials: M
authors.lastname: Makrides
authors.affiliation: Neonatal Medicine, Women׳s and Children׳s Health Network, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: McPhee
authors.affiliation: Institute for Health Research, University of Notre Dame, Australia.
authors.forename: Julie
authors.initials: J
authors.lastname: Quinlivan
authors.affiliation: School of Agriculture, Food and Wine, The University of Adelaide, Australia.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Gibson
mesh_terms: D000328:Adult; D019587:Dietary Supplements; D004311:Double-Blind Method; D005227:Fatty Acids / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D015337:Multicenter Studies as Topic; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic; D018401:Sample Size
chemical_list: D005227:Fatty Acids
keywords: Docosahexaenoic acid; Lost to follow-up; Pregnancy; Research design; Sample size