Change in the prevalence of obesity and use of health care in Denmark: an observational study
Wildenschild, Kjøller, Sabroe, Erlandsen and Heitmann has published a new study on this. Some stuff from the paper:
“In recent years, health care utilization has increased steadily. Data from Statistics Denmark show that the average number of consultations with a general practitioner increased from 7.2/year in 1999 to 8.0/year in 2005 for women and from 4.5/year to 5.3/year for men during the same period. […] Concurrently, with the increased utilization of health care, the prevalence of obesity among those aged 16–99 years increased from 5.5% in 1987 to 11.4% in 2005 according to the DHIS. This rise in prevalence of obesity is in accordance with findings from other Danish studies [5,6] and with the development seen in other industrialized countries.[7,8]
Considering the higher incidence of somatic and psychological illness among obese people, it is conceivable that some of the increase in utilization of health care might be attributed to the increase in the prevalence of obesity. Studies examining the impact of the rising prevalence of obesity on the development of health care utilization are generally absent in previous literature, but several studies have shown an association between obesity per se and utilization of various types of health care.[9–22] […]
The purpose of this study was therefore to examine the impact of the rising prevalence of obesity on utilization of health care in Denmark in 1987–2005. The hypothesis was that the prevalence of obesity would be associated with utilization of health care and thus that the rise in utilization could be partly attributed to the rise in the prevalence of obesity. Another purpose was to examine whether the utilization of health care of obese people has changed during the period.”
I found this paper when looking for data on Danish obesity, which is not as easy to find as you’d perhaps think (for one thing, Statistics Denmark doesn’t have any data on this at all). Even though it’s not easy to find data on this, I did manage to find a 2004 study along the way which is aptly named Major increase in prevalence of overweight and obesity between 1987 and 2001 among Danish adults. The abstract:
The aim of the study was to examine the secular trends in the prevalence of obesity (BMI >or= 30.0 kg/m(2)) and overweight (25.0 <or= BMI < 30.0 kg/m(2)) in Danish adults between 1987 and 2001.
RESEARCH METHODS AND PROCEDURES:
The study included self-reported weight and height of 10,094 men and 9897 women 16 to 98 years old, collected in a series of seven independent cross-sectional surveys. Prevalence and changes in prevalence of obesity and overweight stratified by sex and age groups were determined.
The prevalence of obesity more than doubled between 1987 and 2001, in men from 5.6% to 11.8% [odds ratio (OR) = 2.3, 95% confidence interval (CI) = 1.9 to 2.8, p < 0.0001] and in women from 5.4% to 12.5% (OR = 2.6, 95% CI = 2.1 to 3.2, p < 0.0001), with the largest increase among the 16- to 29-year-old subjects (men, from 0.8% to 7.5%, OR = 10.2, 95% CI = 4.1 to 25.3, p < 0.0001; women, from 1.4% to 9.0% OR = 7.0, 95% CI = 3.5 to 14.1, p < 0.0001). Between 1987 and 2001, the prevalence of overweight increased from 34% to 40% in men and from 17% to 27% in women.
The prevalence of overweight and obesity in Denmark has increased substantially between 1987 and 2001, particularly among young adults, a development that resembles that of other countries. There is clearly a need for early preventive efforts in childhood to limit the number of obesity-related complications in young adults.”
Note that this is not the study  mentioned in the original quote, but the numbers are nevertheless very similar; it’s quite clear that the estimated change that has taken place is within this neighbourhood – when using data like these. Note also that these results most likely underestimate the true increase over time (the type of data they have to work with is one of the main weaknesses of the original study and the authors don’t attempt to hide that); self-reported data on stuff like this are notoriously unreliable and will always cause some bias. This review article found, according to the abstract (couldn’t find a non-gated version online), that ‘The largest increase [in BMI over time] has been documented in studies based on objective data from total populations’, which is not surprising.
Back to the original study on health care utilization – what did they find?
The increase in health care utilization that has occurred in recent years may in part be attributed to a rise in the prevalence of obesity. This increase is particularly seen among obese men. Health care utilization among obese women increased in 1987–2000 only and then leveled from 2000 to 2005. Including variables of obesity-related illness, such as hypertension, diabetes, and back problems, in the analyses suggested a varying significance of these conditions among the subsets of the sample but indicated that they may be at least part of the cause of the increased utilization among obese people. Among men, the association between BMI and health care utilization was dependent on age. Stratification according to age resulted in reduced statistical strength, and results were found to be significant only for those aged 45–64 years and borderline significant for those aged 25–44 and 65+ years. Among men aged 65+, the underweight had the largest probability of health care utilization, as opposed to the other age groups. This finding may be partly attributed to the presence of malignant illness in this group, indicating inverse causality”
These results make good sense to me, particularly that the strength of the association increases with age, though only up to a certain point (the weight-associated effect on -utilization is higher for middle aged than young people, and under-weight individuals is what muddles the waters when looking at the elderly segment + obesity may not be a super big issue if people actually get to reach old age in the first place); it will probably often take a few decades for obesity to cause significant health problems so it makes sense that middle aged obese people are more likely to ‘overutilize’ than people in the lower age brackets. I found this passage interesting:
“From 1987 to 2005, nonresponse to the DHIS increased from 20% in 1987 to 33% in 2005, with the largest increase in nonresponse occurring among those aged 16–24 and 25–44 years. Analyses on nonresponse by BMI to the DHIS in 2005 showed that more obese than normal weight people did not participate. This is in line with results from studies performed during the 1980s that indicated a greater nonresponse among obese people.[36,37] These findings imply that, over the years, nonresponse was generally larger among obese people compared with normal weight people, adding to an increasing underestimation of the prevalences of obesity in the study period. In addition, previous analyses on nonresponse in relation to health care utilization in the DHIS 2000 and 2005 have shown a positive association between nonresponse and health care utilization”
This of course leads to a conclusion which is less strong than it might have been, given better data (the lack of which is hard to blame the authors for):
“We found that the increased burden on the health care system was partly caused by obesity and a change toward an increase in health care use, particularly among obese men. It is likely that the present findings are underestimated due to a possible underestimation of weight, particularly among obese people with health problems, and potential differential selection caused by nonresponse among obese people with health problems.”
One final point, which is very important to remember when interpreting results like these, is that the increased utilization of health care ressources related to increased rates of obesity is not fully explained by (‘standard’) obesity-related illnesses:
“In the present study, associations between obesity and health care utilization were found independent of hypertension, diabetes, and back problems; thus, these illnesses did not fully mediate associations. This is in line with previous findings that suggested that associations between obesity and health care utilization can only partly be attributed to obesity-related illness such as heart disease, hypertension, high cholesterol, diabetes, and arthritis.14”
Even though you don’t get diabetes or hypertension from being fat, you’ll still have to see the doctor more often than will your friends who weigh less than you do.