OBES SURG DOI 10.1007/s11695-014-1304-0
ORIGINAL CONTRIBUTIONS
Cost–Utility Analysis of Gastric Bypass for Severely Obese Patients in Spain Iván Castilla & Javier Mar & Cristina Valcárcel-Nazco & Arantzazu Arrospide & Juan M. Ramos-Goñi
# Springer Science+Business Media New York 2014
Abstract Background To assess the cost–utility of gastric bypass versus usual care for patients with severe obesity in Spain. Methods We have implemented a discrete-event simulation model with two branches: one branch involves gastric bypass, thereby reducing patients’ BMI, and another branch where patients do not undergo surgery. The model analyzes the emergence of comorbidities (stroke, coronary obstructive disease, diabetes, and breast cancer) associated with obesity during a lifetime horizon. The selected measure of effectiveness is health-related quality of life. Both costs and effects are discounted at 3 %. A probabilistic sensitivity analysis is also
performed using second-order Monte Carlo simulation; acceptability curves for different time horizons were also calculated. Results Patients with gastric bypass result in a lifetime increase of 5.63 quality-adjusted life years (QALYs) (18.18 vs. 12.55 QALYs). In addition, because of the reduced spending associated with the treatment of various obesity-related comorbidities, final savings stand at 13,994 €. The total cost of the intervention branch is close to half the cost of the nonintervention branch (17,431 vs. 31,425 €). Conclusions Gastric bypass is an intervention that dominates over the option of not intervening when a lifetime horizon is considered.
Electronic supplementary material The online version of this article (doi:10.1007/s11695-014-1304-0) contains supplementary material, which is available to authorized users.
Keywords Cost–utility . Discrete-event simulation . Gastric bypass
I. Castilla : J. M. Ramos-Goñi Health Services Research on Chronic Patients Network (REDISSEC), Santa Cruz de Tenerife, Spain
Introduction
I. Castilla : C. Valcárcel-Nazco Centre for Biomedical Research of the Canary Islands, Universidad de La Laguna, La Laguna, Spain J. Mar : A. Arrospide Health Services Research on Chronic Patients Network (REDISSEC), Santa Cruz de Tenerife, Spain J. Mar : A. Arrospide Clinical Management Service, Alto Deba Hospital, Mondragon, Spain I. Castilla (*) : C. Valcárcel-Nazco Canary Islands Foundation for Health and Research (FUNCIS), Santa Cruz de Tenerife, Spain e-mail: [email protected] J. M. Ramos-Goñi HTA Unit of the Canary Islands Health Service (SESCS), Santa Cruz de Tenerife, Spain
Obesity is associated with increased mortality, morbidity, loss of health-related quality of life (HRQOL), and psychosocial disorders [1, 2]. Morbidities include cardiovascular disease [1], type 2 diabetes mellitus (T2DM) [2], osteoarticular disease, psychological disorders, and several neoplasias (colon, breast, etc.) [3]. When compared with the general population, obese patients reveal worse physical function, limitations because of physical problems, more bodily pain, worse general health perceptions, and decreased vitality [4]. The impact on self-esteem and sexual function is greater in women than in men [5]. The negative impact on social function and mental health has been related to the stigmatization of obese individuals in society [6]. Severely obese patients are usually refractory to conventional treatment such as dietary treatment, exercise, and behavior modification therapy [6]. Consequently, bariatric
OBES SURG
surgery has arisen as a well-established therapeutic alternative since it has been proven to effectively reverse most of the health effects of obesity detrimental to quality of life (QoL) by means of maintaining weight reduction over time [7, 8]. Moreover, as the current data is insufficient to recommend bariatric surgery as a primary treatment for adult-onset diabetes, there is a growing support to use this intervention for this indication [6, 9]. Gastric bypass (GB) is the most widely used surgical technique for the treatment of obesity and is currently involved in 45 % of all bariatric surgery performed worldwide [10]. Despite its efficiency having been revealed in different countries [11–15], GB was excluded from the Spanish National Health System (NHS) regulation on the maximum access time to health benefits [16]. From an economic point of view, assessing GB requires a balance between the short-term cost of surgery and the medium and long-term savings from the detrimental effects avoided, such as acute myocardial infarction (AMI), stroke, T2DM, and breast cancer. With regard to health outcomes, the focus should be on the benefit of the surgery measured as quality-adjusted life years (QALYs). This study assesses the cost–utility of gastric bypass versus usual care from the perspective of the Spanish NHS using a simulation model that represents the natural history of severe obesity.
Materials and Methods We developed a discrete-event simulation (DES) model that compared the costs and QALYs for severely obese patients in two lifetime scenarios: one where the patient was operated upon with GB and another where the patient was not operated (Fig. 1). DES enables an individual to be characterized (age, sex, etc.) and followed by updating the patient’s health condition and costs according to the most important events that happened to that individual. The relationship between obesity and the development of various comorbid conditions having been proven, we incorporated the occurrence of those comorbidities with the highest cost and incidence as events: AMI, stroke, T2DM, and breast cancer [1–3]. We defined the initial characteristics of patients using the only Spanish study to collect cases consecutively from waiting lists and report changes after 2 years in comorbidities, weight, BMI, and utility values [17]. These comprehensive outcomes were used to fit the model to the actual characteristics of the patients treated by the Spanish NHS. In the study cited, 79 patients aged 18–55 were selected, referred for GB, and followed for 2 years after surgery. At baseline, patients had an average body mass index (BMI) of 50.7 kg/m2 (range 36.6 to 76.3); and 20.25 % had T2DM. Two years after the surgery, the observed BMI reached on average of 31.9 kg/m2 (37 % reduction), which is similar to the 31 % BMI reduction
reported by the Swedish Obese Subjects (SOS) study for GB for the same period [18]. Simulated patients were characterized by age, sex, and BMI. All the age, sex, and BMI range parameters (
ORIGINAL CONTRIBUTIONS
Cost–Utility Analysis of Gastric Bypass for Severely Obese Patients in Spain Iván Castilla & Javier Mar & Cristina Valcárcel-Nazco & Arantzazu Arrospide & Juan M. Ramos-Goñi
# Springer Science+Business Media New York 2014
Abstract Background To assess the cost–utility of gastric bypass versus usual care for patients with severe obesity in Spain. Methods We have implemented a discrete-event simulation model with two branches: one branch involves gastric bypass, thereby reducing patients’ BMI, and another branch where patients do not undergo surgery. The model analyzes the emergence of comorbidities (stroke, coronary obstructive disease, diabetes, and breast cancer) associated with obesity during a lifetime horizon. The selected measure of effectiveness is health-related quality of life. Both costs and effects are discounted at 3 %. A probabilistic sensitivity analysis is also
performed using second-order Monte Carlo simulation; acceptability curves for different time horizons were also calculated. Results Patients with gastric bypass result in a lifetime increase of 5.63 quality-adjusted life years (QALYs) (18.18 vs. 12.55 QALYs). In addition, because of the reduced spending associated with the treatment of various obesity-related comorbidities, final savings stand at 13,994 €. The total cost of the intervention branch is close to half the cost of the nonintervention branch (17,431 vs. 31,425 €). Conclusions Gastric bypass is an intervention that dominates over the option of not intervening when a lifetime horizon is considered.
Electronic supplementary material The online version of this article (doi:10.1007/s11695-014-1304-0) contains supplementary material, which is available to authorized users.
Keywords Cost–utility . Discrete-event simulation . Gastric bypass
I. Castilla : J. M. Ramos-Goñi Health Services Research on Chronic Patients Network (REDISSEC), Santa Cruz de Tenerife, Spain
Introduction
I. Castilla : C. Valcárcel-Nazco Centre for Biomedical Research of the Canary Islands, Universidad de La Laguna, La Laguna, Spain J. Mar : A. Arrospide Health Services Research on Chronic Patients Network (REDISSEC), Santa Cruz de Tenerife, Spain J. Mar : A. Arrospide Clinical Management Service, Alto Deba Hospital, Mondragon, Spain I. Castilla (*) : C. Valcárcel-Nazco Canary Islands Foundation for Health and Research (FUNCIS), Santa Cruz de Tenerife, Spain e-mail: [email protected] J. M. Ramos-Goñi HTA Unit of the Canary Islands Health Service (SESCS), Santa Cruz de Tenerife, Spain
Obesity is associated with increased mortality, morbidity, loss of health-related quality of life (HRQOL), and psychosocial disorders [1, 2]. Morbidities include cardiovascular disease [1], type 2 diabetes mellitus (T2DM) [2], osteoarticular disease, psychological disorders, and several neoplasias (colon, breast, etc.) [3]. When compared with the general population, obese patients reveal worse physical function, limitations because of physical problems, more bodily pain, worse general health perceptions, and decreased vitality [4]. The impact on self-esteem and sexual function is greater in women than in men [5]. The negative impact on social function and mental health has been related to the stigmatization of obese individuals in society [6]. Severely obese patients are usually refractory to conventional treatment such as dietary treatment, exercise, and behavior modification therapy [6]. Consequently, bariatric
OBES SURG
surgery has arisen as a well-established therapeutic alternative since it has been proven to effectively reverse most of the health effects of obesity detrimental to quality of life (QoL) by means of maintaining weight reduction over time [7, 8]. Moreover, as the current data is insufficient to recommend bariatric surgery as a primary treatment for adult-onset diabetes, there is a growing support to use this intervention for this indication [6, 9]. Gastric bypass (GB) is the most widely used surgical technique for the treatment of obesity and is currently involved in 45 % of all bariatric surgery performed worldwide [10]. Despite its efficiency having been revealed in different countries [11–15], GB was excluded from the Spanish National Health System (NHS) regulation on the maximum access time to health benefits [16]. From an economic point of view, assessing GB requires a balance between the short-term cost of surgery and the medium and long-term savings from the detrimental effects avoided, such as acute myocardial infarction (AMI), stroke, T2DM, and breast cancer. With regard to health outcomes, the focus should be on the benefit of the surgery measured as quality-adjusted life years (QALYs). This study assesses the cost–utility of gastric bypass versus usual care from the perspective of the Spanish NHS using a simulation model that represents the natural history of severe obesity.
Materials and Methods We developed a discrete-event simulation (DES) model that compared the costs and QALYs for severely obese patients in two lifetime scenarios: one where the patient was operated upon with GB and another where the patient was not operated (Fig. 1). DES enables an individual to be characterized (age, sex, etc.) and followed by updating the patient’s health condition and costs according to the most important events that happened to that individual. The relationship between obesity and the development of various comorbid conditions having been proven, we incorporated the occurrence of those comorbidities with the highest cost and incidence as events: AMI, stroke, T2DM, and breast cancer [1–3]. We defined the initial characteristics of patients using the only Spanish study to collect cases consecutively from waiting lists and report changes after 2 years in comorbidities, weight, BMI, and utility values [17]. These comprehensive outcomes were used to fit the model to the actual characteristics of the patients treated by the Spanish NHS. In the study cited, 79 patients aged 18–55 were selected, referred for GB, and followed for 2 years after surgery. At baseline, patients had an average body mass index (BMI) of 50.7 kg/m2 (range 36.6 to 76.3); and 20.25 % had T2DM. Two years after the surgery, the observed BMI reached on average of 31.9 kg/m2 (37 % reduction), which is similar to the 31 % BMI reduction
reported by the Swedish Obese Subjects (SOS) study for GB for the same period [18]. Simulated patients were characterized by age, sex, and BMI. All the age, sex, and BMI range parameters (
