A scoping review of Table 2 fallacy in the oral health literature

Coined by Westreich and Greenland in 2013, Table 2 fallacy refers to the practice of reporting estimates of the primary exposure and adjustment covariates derived from a single model on the same table. This study seeks to describe the extent to which Table 2 fallacy is present in the oral health literature and provide recommendations on presenting findings from multivariable-adjusted models and/or interpretation of adjustment covariate estimates that are not the primary exposure.

We conducted a scoping review in PubMed and Scopus of human observational studies published in 4 oral health journals (JDR-CTR, CDOE, JPHD, BMC Oral Health) starting in 2013 until the end of 2018. The resulting articles were exported into Excel and were either included or excluded for full-text review based on six criteria. After categorizing the articles, we exported and summarized the results in SAS.

A total of 1358 articles were initially screened of which 937 articles were excluded based on title or abstract for being animal studies, systematic reviews or meta-analysis, prediction models or descriptive studies. The remaining 421 articles were eligible for full text reviewed of which, 189 (45%) committed Table 2 fallacy. The prevalence of table 2 fallacy appears high in the oral health literature.

The problem of presenting multiple effect estimates derived from a single model in the same table is that it inadvertently encourages the reader to interpret all estimates the same way, often as total effects. Implications and recommendations are discussed.