Prevalence of Complications After Bariatric Surgery - an Epidemiologic Survey
Condition: Complications After Bariatric Surgery
Study type: Observational

Summary: 
      The number of obese is increasing rapidly. Bariatric surgery is used to a greater and greater
      extent as treatment of obesity to obtain a greater and more permanent weight loss. The
      currently most commonly used surgical method is the gastric bypass (RYGB), which so far has
      proved to be the most effective way to achieve a greater and more permanent weight loss,
      reduction and maybe even elimination of many of the obesity-related health complication
      (diabetes, sleep apnea, pain due to osteoarthrosis etc.).

      Bariatric surgery, including RYGB is also associated with medical and nutritional
      complications. This will be a natural consequence of the fact that the food bypasses
      virtually the entire ventricle and 100-150 cm of the upper part of the small intestine after
      a RYGB. Therefore, problems with uptake of for example B12, iron, folate, thiamin,
      fat-soluble vitamins (Vitamins A, D, E and K) copper, zinc and selenium are expected. In the
      light of this, it is decided that all RYGB operated patients must take vitamin B12, iron and
      vitamin D substitution. In spite of this, many develop various nutritional problems after
      RYGB. In addition to these nutritional complications are complications such as hypoglycaemia
      and gallstone attacks after RYGB.

      Nevertheless there is no comprehensive inventory of the occurrence of nutritional
      complications after bariatric surgery neither in Denmark nor in an international context.
      Thus there is no consensus on an optimal postoperative prevention of complications. An
      overview of the occurrence of these problems will be important for assessing and determine
      the indications for bariatric surgery as well as to optimize the prevention of complications.

      To enlighten this we will conduct a cohort study of complications by investigating
      hospitalizations and deaths after RYGB. Moreover we will get an overview on medication use
      before and after RYGB operation in the Central Denmark Region and in the North Denmark Region
      2006-2011 (about 5000 patients).
    

Detailed description: 
      Background Prevalence of overweight and obesity is increasing both in Denmark and in most
      other countries, and as conventional treatment of obesity with lifestyle changes (hypocaloric
      diet, physical activity and behavior modification) rarely leads to large and sustained weight
      loss, it is not surprising that bariatric surgery has taken over more and more of the
      treatment of the most severe cases of obesity. Weight losses are greater than with other
      treatments, and importantly the relatively large weight loss is permanent.

      Positive effects of gastric bypass The currently most commonly used surgical method is the
      gastric bypass (RYGB), which has proven to be a highly effective method of achieving a great
      and permanent weight loss with an approximately 30-40% reduction in the weight, which is
      equivalent to 40-60% reduction of the overweight.Moreover RYGB has shown to provide complete
      remission of prior type 2 diabetes in up to 80% of cases at short observation time (up to 2
      years after surgery) and about 50% remission at longer time follow-up (> 5 years).

      Moreover data suggest that after RYGB there is a reduced consumption of antihypertensive
      drugs in 51 % and of lipid-lowering drugs in 59 %.

      Psychiatric complications after gastric bypass There are conflicting results in the
      literature when examining the consumption of antidepressants. Some studies find a reduced
      consumption of antidepressants after bariatric surgery within the first two years, others
      show that consumption is almost unchanged overall and cohort follow-up studies show an
      increased quality of life.

      Nevertheless, there is an increased incidence of suicide after bariatric surgery, which
      argues against an unambiguous improvement in psychological well-being.

      Nutritional complications after gastric bypass Bariatric surgery including RYGB is also
      connected with some medical and nutritional effects or complications. This is not surprising
      since RYGB "bypasses" virtually the entire ventricle and 100-150 cm of the upper part of the
      small intestine, so problems with the inclusion of, for example B12, iron, folate, thiamin,
      fat-soluble vitamins (Vitamin A, D, E and K) copper, zinc and selenium are expected.
      Therefore, it is recommended that all RYGB operated patients substitute vitamin B12, iron and
      vitamin D. Despite this many develop various nutritional problems after RYGB which in the
      long term can result in irreversible neurological damage, osteoporosis and anemia. Such
      complications are sparsely registered in Denmark.

      The complications are often developed long time after the operation, at a time when the
      patients are no longer followed in specialized departments which report all complications to
      the Danish Obesity Register, in the same way as surgical complications are reported. There is
      no international consensus on postoperative vitamin substitution, which may be due to the
      previous lack of evidence of nutritional complications.

      Surgical complications after gastric bypass

      International studies have shown that mortality of bariatric surgery ranges between 0.24 and
      2.77% depending on the operator and the hospital, and perioperative morbidity ranges between
      6.92 and 8.85% also depending on the operator and the hospital.

      Moreover complications such as abdominal pain of varying degree and the development of
      gallstones are frequently seen.

      It is still unresolved how extensive a problem these nutritional complications after
      bariatric surgery in Denmark are, we want to clarify the occurrence of these complications in
      Denmark. This will provide an overview of the positive as well as the negative impact of
      bariatric surgery and thus will be decisive to assess and determine the indications for
      bariatric surgery as well as to optimize the prevention of complications.

      The investigators will in this project make a cohort study in which all RYGB operated
      patients in the Central Denmark Region and the North Denmark Region during the period 2006 -
      2011 (about 5000 patients) will be included and from the combination of the various registers
      (see research plan) we will be able to estimate e.g. mortality, readmissions in the surgical
      department (reoperations), length of stay in the surgical department / intensive care unit
      and the length of patient follow-up in a medical context, referrals and readmissions in
      medical wards,

      The purpose of this cohort study is to describe the prognosis for patients who have had a
      RYGB in the Central and North Denmark Region 2006-2011.

      The specific objective is to compare the Danish data for the occurrence of complications and
      the beneficial effects of RYGB with international data in order to demonstrate the quality of
      RYGB made in Denmark.

      The investigators will examine:

      a Mortality after RYGB surgery (30-day mortality, 90-day mortality and total follow-up
      period: 2-7 years after surgery) b Surgical complications of RYGB by studying such as of
      anastomosis ulcers, bowel obstruction, ileus / internal herniation, peritonitis, gallstones,
      kidney stones, abdominal pain and infections.

      c Consumption of drugs two years leading up to the surgery compared with consumption 2-7
      years after RYGB. Here the focus will be on the consumption of antidiabetics,
      antihypertensives, statins, aspirin, antidepressants and analgetics on prescription to
      illuminate the psychological, medical and nutritional complications following RYGB.

      Thus, the investigators wish to achieve a better documentation of both the positive effects
      after RYGB (weight loss, remission of diabetes, quality of life, etc.) and the negative
      health effects (mortality, surgical and nutritional) in order to provide a better founded
      approach to this form of treatment.

      Method The investigators will include all RYGB-operated persons in the period 2006-2011
      residing in Central Denmark Region (CDR) and in the North Denmark Region (NDR). These
      patients' social security numbers will be provided by the CDR and NDR (agreed). This is
      considered to be about a total of approximately 5,000 people (about 3,300 from CDR and
      approximately 2,000 from RN).

      The variables the investigators want to focus on in relation to this epidemiologic study are:

        1. Mortality after bariatric surgery: Information about death and cause of death will be
           provided from relevant registries (The Danish Register of Causes of Death etc.).

        2. Surgical complications after bariatric surgery: Surgical hospital readmissions after
           bariatric surgery with diagnoses that can be related to the original obesity surgery.

        3. The investigators will use data from the The Danish National Database of Reimbursed
           Prescriptions on the consumption of prescription drugs in this group of people as
           antidiabetics, vitamin substitution as B12/thiamin, iron supplements and
           antidepressants. As a control group will be used consumption of drugs in a sex and age
           matched group.

      Based on these data and data directly from The National Bariatric Surgery Register we will
      get an overview of possible predictors of complications of RYGB such as age, gender,
      preoperative BMI, previous gastric banding surgery and preoperative comorbidity.

      The investigators will conduct a stratified analysis of data from people in Central Denmark
      Region which will be involved in the second subproject.

      This part of the project will be carried out in close collaboration with the Department of
      Clinical Epidemiology at Aarhus University Hospital, who has access to the necessary
      databases.

      Statistical considerations and power calculation In the cohort study, the investigators
      expect a cohort of approximately 5000 patients.

      The statistical evaluation of the data will be performed in collaboration with the Department
      of Clinical Epidemiology, Aarhus University Hospital.

      There will be conducted statistical analysis to identify possible predictors of complications
      of RYGB such as BMI before surgery, age, comorbidity, etc. Statistical analysis will be
      carried out by the philosophiae doctor (PhD) student.

      Description of participants We will include all patients who have undergone gastric bypass
      surgery in the Central Denmark Region and the North Denmark Region in the years 2006-2011
      (about 5000 patients).

      Risks, side effects and disadvantages There is not considered to be any risks, side effects
      or disadvantages associated with participation in the epidemiological study.

      Respect for the subjects' physical and mental integrity The project has been approved by the
      Danish Data Protection Agency (no. 1-16-02-153-13)

      The Act on Processing of Personal Data will be respected. The study will also be reported to
      the Clinical Trials and conducted in accordance with the Helsinki Declaration II.

      Publication of results Both positive, negative and inconclusive results will be published and
      sought to be published in English-language, peer-reviewed journals as original publications
      and with the PhD student as first author.

      Perspectives The investigators expect to identify positive and negative consequences for RYGB
      and thus optimize the basis on which patients and physicians in the future will be able to
      decide on surgery. This will also better prevention of complications and thus save patients
      and communities of loss, economic as well as social and personal. The project will hopefully
      form the basis for the continuation of longer follow-up studies. Moreover, the results set
      the stage for the development of new more "gentle" obesity surgery.
    

Intervention name(s): Bariatric surgery
Intervention type(s): Procedure
Other intervention name(s): All patients with a primary gastric bypass operation
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        All patients WHO have had bariatric surgery in the Central and North Denmark Region
        2006-2011
      
Keywords: Bariatric surgery; Complications; Drugs