Evaluation of different methods to handle misreporting in obesity research: evidence from the Canadian national nutrition survey.

The association of dietary exposures with health outcomes may be attenuated or reversed as a result of energy intake (EI) misreporting. This study evaluated several methods for dealing with implausible recalls when analysing the association between dietary factors and obesity. We examined data from 16,187 Canadians aged ≥12 years in the nationally representative Canadian Community Health Survey 2.2. Under- and over-reporting were defined as the ratio of EI:estimated energy requirement <0·7 and >1·42, respectively. Multinomial logistic regression-generalised logit model was conducted to test the utility of different methods for handling misreporting, including (a) adjusting for variables related to misreporting, (b) excluding misreported recalls, (c) adjusting for reporting groups (under-, plausible and over-reporters), (d) adjusting for propensity score and (e) stratifying the analyses by reporting groups. In the basic model, EI showed a negative association with overweight (OR 0·988; 95% CI 0·979, 0·998) and obesity (OR 0·989; 95% CI 0·977, 0·999). Similarly, the association between total energy density and overweight (OR 0·670; 95% CI 0·487, 0·923) and obesity (OR 0·709; 95% CI 0·495, 1·016) was inverse. Among all methods of handling misreporting, adjusting for the reporting status revealed the most satisfactory results, where a positive association between EI and overweight (OR 1·037; 95% CI 1·019, 1·055) and obesity (OR 1·109; 95% CI 1·082, 1·137) was observed (P<0·0001), as well as direct positive associations between energy density and percentage energy from solid fats and added sugars with obesity (P<0·05). The results of this study can help advance knowledge about the relationship between dietary variables and obesity and demonstrate to researchers and nutrition policy makers the importance of adjusting for recall plausibility in obesity research, which is highly relevant in light of global obesity epidemic.