Association between physical multimorbidity, body mass index and mental health/disorders in a representative sample of people with obesity.

Background: Obesity is known to be associated with poor mental health. Studies suggested that multimorbidity might explain the consequences of obesity on mental health. The objective of the present study was to examine to what extent physical multimorbidity and the severity of obesity were associated with mental health and with mental disorders.

Methods: Cross-sectional study including a weighted representative sample of individuals in obesity from the province of Quebec included in the 2013-2014 Canadian Community Health Survey (N=1315) and test of the replicability of the association in the three previous cycles (2011-2012, N=1180; 2009-2010, N=1166; 2007-2008, N=1298).

Results: Adjusted logistic regressions showed that when obesity classes and physical multimorbidity were considered, the latter was preferentially associated with poor perceived mental health (OR 3.58, 95% CI 2.07 to 6.22), psychological distress (OR 3.71, 95% CI 2.14 to 6.42), major depressive episode (OR 5.16, 95% CI 2.92 to 9.13), mood disorders (OR 2.31, 95% CI 1.41 to 3.78) and anxiety disorders (OR 2.46, 95% CI 1.46 to 4.16). The same associations were confirmed in the previous cycles. Obesity class was only associated with stress (OR 2.05, 95% CI 1.36 to 3.07), but this association was not confirmed in the other cycles. Both physical multimorbidity and severe obesity were associated with mental multimorbidity.

Conclusion: Among people with obesity, physical multimorbidity is preferentially associated with poor mental health/disorders. There is an existence of a somatic-mental multimorbidity which should be assessed and prevented in the management of obesity.