Trends in obesity and multimorbidity in Canada.

Very few studies have examined trends in multimorbidity over time and even fewer have examined trends over time across different body mass index (BMI) groups. Given a general decline in death rates but increased cardiovascular risk factors among individuals with obesity, the trend in the association between obesity and multimorbidity is hypothesized to be increasing over time. The data for our study came from the 1996-97 National Population Health Survey and the 2005 and 2012-13 Canadian Community Health Surveys (N = 277,366 across all 3 surveys). We examined trends in the association between BMI groups and multimorbidity using a logistic regression model. We also investigated trends in the prevalence of specific chronic conditions, pairs of chronic conditions and different levels of multimorbidity across BMI groups. We found significantly greater levels of multimorbidity in 2005 (OR = 1.42; p < 0.001) and 2012-13 (OR = 1.58; p < 0.001) relative to 1996-97. Changes in multimorbidity levels were much greater among individuals with class II/III (OR = 1.48; p = 0.005) and class I obesity (OR = 1.38; p = 0.001) in 2012-13 relative to 1996-97. Much of the increase in multimorbidity among individuals living with obesity was due to increases in 3+ chronic conditions and conditions in combination with hypertension, and the greatest increase was found among seniors living with obesity. Our results highlight the need for interventions aimed at preventing obesity and the prevention of chronic conditions among individuals with obesity, especially among seniors.