A total of 4100 references were identified that included the words “cost” and “obesity”. Eighty-two articles or book chapters were selected that made reference to the effectiveness, cost-effectiveness, cost-benefit, or cost-utility of BS. In the final review, 66 publications were included that provided specific numerical data (Fig. 1). These studies were grouped by topic for posterior analysis, and the complete texts were reviewed. The publication dates ranged between 1999 and 2012.

Fig. 1.

Results of the meta-search and studies included in the review.

(0.32MB).

The evaluation of obesity management strategies requires prior analysis of the costs imposed on the healthcare system.15,16 A review published in 2011 provided data from 19 European studies that evaluated the impact of obesity on the cost of different diseases.17 For patients with diabetes, obesity increases the health costs by €812 per year for type 1 diabetes and by €454 for DM2; a 78% higher cost per capita has also been reported when obesity and diabetes are associated.17,18 In Spain, obesity is responsible for 43% of the total costs related to DM2, more than 32% of the costs related to arthropathies, and more than 30% of the costs related to cardiac diseases.23 In European countries, obesity contributes to a per capita increase of 20% in health care costs, and this increase in pharmaceutical expenses is 68% higher compared to normal weight patients.17,19 Numerous studies have reported the estimated annual cost of obesity for European countries. In 2002, in Germany, this cost was €4854 million, to which an estimated indirect cost of €5019 million was added.20 In Ireland, the annual hospital cost derived from obesity (without taking into account health care centres or drugs) was €11.1 million in 2003.22 In Spain, the costs associated with obesity account for 7% of the total health care cost; after updating these costs to 2011, this amount was approximately €2880 million/year23 (Table 1). In Denmark, the estimated total cost has not been published, but an extra yearly health cost of 1000$/person has been calculated for patients between 50 and 64 years of age with a BMI >30. Obesity is also responsible for increasing costs and worsening results following multiple surgical procedures, ranging from simple appendicitis or the placement of an orthopaedic prosthesis to organ transplant.24–27

No data related to the indirect costs of BS in Spain or other countries were found (with respect to the cost of sick leave, follow-up, examinations, etc.). Only data with respect to direct costs have been reported.

In the case of BS, the SNHS has defined a DRG that includes the surgical treatment of obesity with an average cost of €7468. According to data from the statistical portal of the SNHS, 2830 yearly cases were treated in hospitals of the public health care network between the years 2005 and 2010, with an average length of stay of 6.8 days. The estimated cost of this surgery in other countries is higher. For example, in the US, the average cost per BS procedure performed through Medicare between 2004 and 2008 was $19746.28 In Finland, the average cost per procedure in 2011 was approximately €14600.29

An increase in the survival of morbidly obese operated patients vs non-operated patients has been shown in studies with 5–10 years of follow-up data (Table 2). In particular, the mortality rate of patients who underwent BS was shown to decrease between 31% and 89% in studies that analysed between 2000 and 66100 patients who were followed for 5–10 years. BS has also been associated with a decrease in the incidence and mortality related to cardiovascular diseases and cancer.30–33 With respect to the evolution of several comorbidities, several studies and meta-analyses have been published with sample sizes between 3000 and 12000 surgically intervened (SI) patients; in these studies, remission of DM2 in 86.6% of patients,33 improvement or resolution of hyperlipidemia in 70% of patients, remission of HTN in 61.7% of patients, and remission of OSA in 83.6% of patients were reported.14 Likewise, a reduction between 32 and 56% of coronary diseases and a 60% reduction in the incidence of cancer have been observed.34–36 In addition, a 10-year increase in the life expectancy of operated morbidly obese patients vs non-operated patients has been estimated.30,37

To evaluate the direct tangible benefits related to BS, the following aspects were considered: (1) the savings in medications for the treatment of resolved comorbidities; (2) the savings in health benefits (including CPAP, glucometers, specialist consults, orthopaedic prostheses, etc.); and (3) the resolution of work-related disabilities.

These benefits were highlighted in Canada following the study of Christou et al.,31,38 where operated patients demonstrated significantly lower rates of diagnosis of cancer (2% vs 8%), cardiac problems (5% vs 27%), infections (9% vs 37%), arthritis (5% vs 12%), and respiratory problems (3% vs 11%). Moreover, the health costs of the group that did not receive the SI far exceeded those of the operated patients after 3 years of follow-up. The cardiovascular risk (measured by the Framingham method) also decreased by 79% after BS, according to a study conducted by the Mayo Clinic, which compared 197 gastric bypass surgery patients with 163 non-operated morbidly obese patients.39 With respect to the savings from unnecessary medicines, the mean cost of treatments per patient decreased by 66%, where the cut-off point for the cost-effectiveness ratio was observed at 2.5 years after surgery; in addition, this favourable result for the group of operated patients remained at the fourth year of follow-up40 (Table 3).

The following are considered indirect, tangible benefits of BS: (1) re-entry into the job market and a decrease in unemployment rates; (2) reduction in sick leave; and (3) decrease of early deaths in the active population. The decreased rates of mortality among morbidly obese individuals after BS and the 10-year increase in life expectancy translate into an increase in working life, which is associated with income and tax payments.

A study conducted in the Plains region of southern Texas revealed the financial impact of BS in this area; in particular, this study looked at sick leave, job loss, and tax payments in a group of 150 morbidly obese individuals before and after BS. Comparing these results to the employment data of the regional database, morbidly obese individuals demonstrated a productivity equivalent of 87.8% that of a non-obese worker. The calculated impact of morbid obesity in this region involved a financial loss of US$ 364793497 per year, the loss of 1977 jobs, and an indirect tax loss of $13209196. In the case of the SI patients, considering a 3% yearly discount rate, the net benefit was US$ 9907068233 (considering the cost of BS to be between US$ 17000 and US$ 25000 per patient).41

Moreover, in the report of health technology produced by the National Institute of Clinical Excellence Guidelines for Bariatric Surgery, it was estimated that the incremental cost-effectiveness ratio for gastric bypass is 6289 pounds, which is well below the cut-off point of 30000 pounds considered by the National Institute of Clinical Excellence to be cost effective. This places BS among the most profitable interventions.42

With respect to the intangible benefits of BS, we considered the following: (1) the improvement in quality of life; (2) the improvement in well-being; (3) the increase in the possibilities of higher professional education; and (4) the possibility of higher job training.

The monetary value attributable to the indirect, tangible, and intangible benefits is complex. In a study conducted in the UK with a group of morbidly obese individuals who underwent gastric bypass, the rate of paid employment after BS increased from 58% to 76%. Moreover, self-employed workers increased their total work time from 1023 to 1611h, representing a 57% increase.46

Multiple studies have shown an improvement in the quality of life of patients after receiving BS.43–45 With respect to the cost-utility analysis used to quantify and evaluate the costs according to the unit of earned consequence of 2 or more health intervention alternatives, a health intervention tends to be considered as profitable in terms of cost-utility if it costs less than US$ 50000 per quality-adjusted life-year (QALY).47 In 2004, the American Society for Metabolic and Bariatric Surgery (ASMBS) published a cost-utility study comparing the results of diet and exercise vs gastric bypass in young women with a BMI >40. Gastric bypass was shown to be a more effective alternative with a cost-utility ratio of US$ 7126/QALY (in the branch of medical treatment, no gain was observed in years adjusted by quality of life).48 In Finland, a cost-utility study at 10 years estimated the medical treatment cost of morbid obesity to be around €50000 and that of BS to be around €33870, with an advantage in favour of BS of 7.63 QALY vs 7.05 QALY of medical treatment. Moreover, the cost of medical treatment is much higher than surgical treatment after 5 years of follow-up.29

Is the cost-effectiveness of BS the same for all morbidly obese patients? A recent meta-analysis evaluated BS in relation to various sub-types of the population. For this, the sample included studies published since 2003 with a minimum of 1B degree of evidence. The obese population with a BMI ≥35kg/m2 was stratified according to the presence or absence of comorbidities (HTN, DM2, coronary heart disease, dyslipidemia, and cerebral disease), 3 categories of BMI, and the application of SI or no-SI. The mean age was 39.7 years, with no differences reported between groups. The global result of this study suggested that BS is profitable for patients with a BMI >35kg/m2, with an increasing benefit as the BMI value increases. Costs are also saved and the efficacy is improved for patients with severe obesity, with a BMI >50kg/m2, and with at least 1 comorbidity. In contrast, for individuals without co-morbidities and a BMI >50kg/m2, BS continues to cost $1904 per earned QALY. In any case, this procedure continues to be more profitable for such patients in comparison to those with lower BMIs and those without comorbidities (US$ 3872 for patients with a BMI between 35 and 40kg/m2 and US$ 3770 for a BMI between 40 and 50kg/m2). Moreover, the life expectancy for individuals without surgical treatment was reduced by approximately 6.5 years.49 Some studies have also pointed towards a greater cost-effectiveness of BS in the sub-group of patients with DM2.50–53

The impact of a given health intervention on the health of the population depends, to a large extent, on accessibility, given that patients who cannot gain access to treatment cannot obtain the calculated benefit. In Canada, the US, and the UK, less than 1% of possible candidates receive BS, and the waitlists are very long (with an average of 5 years in Canada).54,55 In Spain, according to data regarding the prevalence of morbid obesity and the yearly interventions registered by the Spanish Ministry of Health and taking into account the annual survey conducted by the Spanish Society of Obesity Surgery (SECO, for its initials in Spanish), in the last 5 years, 5.24% of possible candidates have received SIs. Among the causes for this low accessibility, the following factors should be considered: deficits in the services offered by the SNHS due to the scarcity of specialised multidisciplinary teams; deficits in the health education of candidates who do not understand the consequences of their obesity and the available therapeutic options; deficits in the training of health care personnel regarding the therapeutic options available for patients with morbid obesity; and the socioeconomic discrimination that morbidly obese patients frequently experience. Indeed, society often blames morbidly obese individuals for their situation and makes access to treatment difficult, even at primary health care centres, which jeopardises the equality of the health care system.56