Utilization of out- and inpatient health services by obese adults: a population-based study in the Augsburg region, Germany.

The aim of this study is to compare out- and inpatient health services utilization by obese and normal weight adults. In a subsample of the KORA-Survey S4 1999/2001 in the Augsburg region, Germany (n = 947, age: 25-74 years), number of visits to general practitioners (GP) and inpatient hospital days were self-reported in three computer-aided telephone interviews (CATI) over half a year. Body mass index, based on measured body height and weight, was used to define obesity according to WHO classification. Participants, stratified in normal weight (18.5 < or = BMI < 25), preobese (25 < r = BMI < 30), obese class 1 (30 < or = BMI < 35) and obese classes 2-3 (BMI > or = 35), were compared via logistic, zero-truncated negative binomial, and multinomial models to elucidate obesity's associations with utilization at all, its frequency, and high utilization. Sex, age, social class, health insurance, and place of residence were adjusted for in all models. Respondents in obesity class 1 were more prone to report at least one visit to a GP than those normal weight (OR = 1.84, p < 0.01), while obesity classes 2-3 were associated with frequent (IRR = 1.63, p < 0.05) and high utilization (OR = 3.57, p < 0.05). Regarding days in hospital, only the extremely obese (i. e. classes 2-3) reported significantly more utilization than those normal weight (days if hospitalized at all: IRR = 3.24, p < 0.05; high utilization: OR = 5.4, p < 0.01). Sex did not play a significant role in any model. Older respondents reported more utilization in terms of GP-visits, while only tending to do so regarding inpatient utilization. Both those with statutory (vs. private) health insurance and rural (vs. urban) place of residence had higher odds to visit a GP at all. Results point to an excess utilization of out- and inpatient health services by especially extremely obese adults, and underline the need to contrast obesity classes 2-3 vs. 1 in health services utilization research.