BACKGROUND: Higher rates of weight-related comorbidities are associated with body mass index (BMI) in individuals who have overweight/obesity. Relationships between BMI, health outcomes and health-related costs differ across populations and geographic regions.

AIM: The aim of this study was to quantify the association between BMI and health outcomes among adults in Italy.

METHOD: The Italian data from the 2013 European National Health and Wellness Survey (NHWS) were used (N=10,000). The NHWS is a cross-sectional general health survey administered to a representative sample of adults in France, Germany, UK, Italy, and Spain. Analyses included all adults who had a BMI >18.5 kg/m² (based on self-reported height and weight) and had not had bariatric surgery. Health-related quality of life (HR-QoL) was assessed via SF-36v2 questionnaire scores; work productivity and activity impairment (WPAI) via WPAI questionnaire scores, healthcare resource use via number of self-reported healthcare provider and emergency room visits; the indirect/direct costs associated with healthcare resource use were estimated using average-values reported in the literature and converted to Euros (2013 exchange rates). Regression models explored differences among BMI classes with respect to the outcome measures, controlling for demographic and health history variables. Analyses were replicated for three subgroups: respondents with type 2 diabetes (T2D), hypertension, and pre-diabetes.

RESULTS: N=9,433 respondents met inclusion criteria. 52.26% of respondents had BMI <25 kg/m2 (normal weight), 34.85% had BMI 25–<30 kg/m2 (overweight), 9.49% had BMI 30–<35 kg/m2 (obesity class I), 2.28% had BMI 35–<40 kg/m2 (obesity class II) and 1.12% had BMI ≥40 kg/m2 (obesity class III). All BMI classes were significantly different from obesity class III respondents with respect to Mental Component Summary scores (adjusted means = 44.85, 45.05, 44.78, 44.30 and 42.82 for normal, overweight, obesity class I, II and III, respectively); Physical Component Summary scores (adjusted means = 51.83, 50.93, 49.62, 47.77 and 45.07), and health utilities (Adjusted means = 0.70, 0.70, 0.68, 0.67 and 0.65) (p<0.05). Increasing BMI classes were associated with increasing overall work impairment (adjusted means = 19.12%, 21.56%, 21.57%, 26.65% and 30.67%) and indirect costs (adjusted means = €4256, €4800, €4804, €5934 and €6828), and normal weight respondents were significantly different from obesity class III with respect to these measures (p<0.05). Similar patterns were observed in the T2D, hypertension, and pre-diabetes subsamples.

DISCUSSION: Nearly half of adults in our sample had a BMI of 25 kg/m2 or greater. A significant HR-QoL impairment, activity impairment, and economic burden was observed as BMI class increased. Improved management of obesity in Italy could have important benefits for the patient and society.

The association between body mass index and health outcomes in Italy