Knowledge, Perceptions and Reporting Practices of Theoretical Design in Causal Observational Epidemiological Studies on the Role of Antibiotic Use in the Occurrence of Asthma in Children.

Good research is driven by study design encompassing theoretical design, design of data collection and design of data processing. In epidemiological research, theoretical design is based on a functional relationship between the occurrence and determinants studied (occurrence function) and should also define that part of the theoretical population and the context to which the results pertain (domain). Both are essential for the design of data collection, the design of data processing and the interpretation of the study results and should be explicitly reported. In order to gain insight into the role of theoretical design in the entire research process before publication, it was decided to informally question the corresponding authors of a selection of 30 articles (20 most recent and 10 less recent) reporting on causal observational epidemiological studies on asthma and early life exposure to antibiotics. The objective was to appraise the perceived knowledgeability of theoretical design among the authors of the selected articles. Fifteen authors responded. Authors were asked to indicate their knowledgeability with the concepts of theoretical design, causal theory, confounding and effect modification on a 5-level Likert scale. Other questions were related to the theoretical design of their study. The vast majority of the authors perceived themselves to be moderately to extremely knowledgeable with confounding and effect modification. Perceived knowledgeability of theoretical design and causal theory was more diverse. When provided with options for an occurrence function, almost all authors indicated "current occurrence as a function of past exposure" for their study. Nevertheless, half of these authors conducted their study based on "future occurrence as a function of current exposure". Even though the authors perceive themselves to be knowledgeable with theoretical design, this is not reflected in their articles. Theoretical design should be well known, implemented and explicitly reported.