4.1. Main Findings and Comparisons with Other Studies
Our study had three objectives. First, we wanted to record the prevalence of physician consultations, according to BMI categories. The results have shown that physician consultations as well as their frequency are high within each BMI category and increased with obesity. Two reasons might explain our findings. First, the fact that the rate of physician consultations in the total sample was high (64.2%), a finding which has been also reported in other studies [18
]. Secondly, the high consultation rate of the obese population, in relation to the fact that the majority of obese users (67%) have made three or more visits during a one year period imply that the obese population are heavy users of primary care and impose an additional burden on the health care sector in terms of impaired health. Indeed, previous studies have shown that obesity is associated with two or more co-morbidities [24
], increased risk of disability [25
] and decreased HRQL [10
] while in terms of more physician visits implying greater health care costs [26
In an attempt to quantify the impact of overweight and obesity on physician consultations, which was the second objective, odds ratio estimates have shown a moderate impact of overweight on both physician consultations (11.8%) and frequency of visits, i.e.
, three or more visits (12.3%) despite the statistical insignificance. As for obesity, the results have shown a significant impact, with the odds of consulting a physician and of making three or more visits were two times higher the odds of normal weight users. The increased burden on health care use by obese subjects is interpreted by many confounding factors that are associated with obesity and furthermore with poor health conditions. The existence of co-morbidities is a significant factor which can lead to further morbidity and mortality [27
]. Age is another risk factor of developing obesity and at the same time is associated with many medical conditions. Obesity is also associated with disadvantaged socioeconomic status i.e.
, low educational level, as our results have shown and other studies have confirmed [10
], which is in term related to lower health knowledge [29
Our third objective confirmed the fact that physician consultations correspond to the need for care, as defined by the risk group of the individuals. Overweight and obese were more likely to consult a physician than those with normal weight. Overweight users were more likely to be men, married, having primary education and suffering from chronic diseases, whereas obese users were more likely to be married, having primary education, suffering from chronic diseases, and having impaired physical health. Multinomial regression analysis -controlled for age- has shown that the primary cause of increased use of physician contacts by overweight and obese was poor health status due to the presence of co-morbidities, poor HRQL (specifically physical health) and low educational level which has been extensively-documented to be associated with poor health status [30
Greater health need and therefore poorer health status as implied by the three confounding factors is associated with greater use, assuming the existence of vertical equity in the relationship between BMI and primary health care use. A particularity that could explain both the high rate of physician consultations and the existence of vertical equity is the structure of the Greek public primary health care sector, in which access is free through insurance funds and the NHS. Another significant confounding factor was marital status. As previous studies have shown, marital status influences the likelihood of developing overweight and obesity [32
], or changes in social roles such as marriage influence physical characteristics such as body weight [33
Concerning frequency of visits, we noted that in an unadjusted model obesity was associated with three or more visits, but in an adjusted model where other confounding variables were included, no association between BMI and frequency of visits was observed. Our results were not in accordance with previous study [34
] which had shown that obesity was associated with the mean number of primary care visits, diagnostic services and clinic charges. Our results suggest that the association between BMI and frequency of use is more a function of the relationship between BMI and impaired health status as determined by co-morbidities, hospitalization and HRQL.
A point that requires consideration is the inclusion or not of subjects with obesity-related co-morbidities such as diabetes 2, hypertension, etc
. in the analysis (whether obesity generates higher health care use) as this might lead to biased outcomes. Previous studies have chosen two different approaches. The first approach [35
] proposed the exclusion of subjects with certain co-morbidities which can lead to an over-adjustment of the statistical control for such diseases because they were thought as intermediates along the causal pathway between increased BMI and increased health care use [36
]. According to the second approach [19
] obesity-related co-morbidities were included and SF-36 physical health was used as a surrogate for co-morbid conditions. In our study we used both approaches and the results remained the same, suggesting that obesity-related co-morbidities did not bias the results, and that the second approach presented by Bertakis [19
] is more appropriate. Of course further research is needed.