Our study findings suggest that in the European countries participating in the SHARE study, overweight and obesity did not represent a barrier to the receipt of preventives services. On the contrary, these results support our initial hypothesis suggesting that overweight and obese individuals would receive at least similar levels of preventive services than normal weight persons, because of the increased number of health care opportunities and the physicians’ awareness of the morbidity and mortality burden associated with excess weight. Similar trends were found for both gender and in all 10 countries despite their diverse health care systems and utilization patterns.
Strengths of our study included a large database of representative samples of noninstitutionalized individuals from 10 European countries and the use of standardized questionnaires and procedures. However, the data source had some potential limitations. First, height and weight were self-reported. Because persons generally overestimate their height and underestimate their weight, particularly if they are obese, BMI tends to be underestimated.36,37
The true percentage of the overweight and obese population may therefore be higher than our estimates. Second, selection bias cannot be ruled out because respondents to the supplementary questionnaire showed slightly more favorable health and health-related attitudes and because the overall response rate to the latter was moderate (51%), particularly due to a poor participation in Switzerland. Nonetheless, the age, sex, subjective health, and BMI characteristics of the Swiss sample were similar to those of the 2002 Swiss Health Care Survey (unpublished results). In addition, results of the country-level analysis were the same, in spite of differences in the countries’ response rates. Third, because of the unavailability of stratum and cluster information, we could not completely take into account SHARE’s complex survey design, and our variances might have been underestimated. However, as we did not found a significant association between BMI and cancer screening or influenza immunization, and the calculated 95% CI of the significant associations were relatively small, our results and discussion should be robust to slightly larger variances. Finally, the use of self-reported data could result in reporting and/or recall biases, which are however, unlikely to be different across BMI categories. This non-differential misclassification across BMI classes may also be true for colorectal cancer screening time windows, which were longer than those usually considered (10 years limits considered in our study, instead of sigmoidoscopy every 5 years and colonoscopy every 10 years).38
Our results run counter to the BMI-screening association observed in population-based studies from the United States and elsewhere, which showed obesity-related screening disparities: multifactorial causes delayed and/or prevented the receipt of preventive services of excess weight individuals.13–15,18,20
There could be several explanatory hypotheses for this. In fact, differences in health insurance coverage (almost universal health insurance coverage in Europe in contrast to the more than 40 millions of un- or underinsured U.S. residents25,26
) may explain inequalities in health care accessibility. However, adjustment for insurance status did not fully explain the negative associations found in the United States,13–15,18,20
recently suggested that low screening rates among obese American women were not necessarily a consequence of decreased health care access, as 90% of their study participants had health insurance. In addition, studies from European countries with almost universal health insurance coverage showed conflicting results. In Germany40
but not in Spain,23
authors found negative associations between BMI and preventive services. However, these later three studies did not adjust for insurance status. Then, residual and/or unmeasured confounding by socioeconomic status may still be present despite their adjustment in the modeling process. Because excess weight individuals are more likely to have a lower socioeconomic status,41,42
the decreased odds ratios for preventive services may in fact reflect socioeconomic rather than weight-related differences, in these European studies. Other explanations could be study design differences (low vs high response rates; use of self-administered vs interview-based questionnaires) and/or the overall low uptake of screening test in SHARE compared to American studies, which could make it more difficult to detect differences between groups. The absence of decreased receipt of preventive services among obese, compared to normal weight Europeans, may also be because of Europe–United States possible differences in the prevalence of moderately and severely obese individuals, particularly of obesity classes II (BMI 35–39.9 kg/m2
) and III (BMI
), which are more prevalent, and disproportionately increased in recent years in the United States.43
While in the United States, the adult prevalence of obesity class III was 4.8%,44
and the veterans’ prevalence of obesity classes II and III was close to 9%,45
the overall prevalence of obesity classes II and III was only 4% among SHARE participants aged 50–79 years. As barriers to health care seem to increase with BMI,39
this difference in the BMI distribution of Europeans and Americans may have obscured a BMI-screening association mostly determined by extreme obesity. However, subsidiary analyses of SHARE data, looking at the specific effect of obesity class I and classes II–III, did not reveal different trends. Finally, we may hypothesize that weight bias and discrimination, shown to be present among health care professionals,46,47
and also reported by obese individuals themselves,48–50
might be less pronounced in Europe than in the United States.
In conclusion, this study sheds light on the association between body weight and preventive services in the10 European countries participating in SHARE. As expected from the greater disease burden of overweight and obese individuals, a trend towards an increased use of these services, even though not always of great magnitude and significance, was described, irrespective of the health care system and country considered. Generalization to other indicators of quality of care is however not possible. Therefore, further research is needed to reexamine this issue in Europe, to assess health care accessibility and quality in other domains of care.