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The clinical effectiveness and cost-effectiveness of surgery for people with morbid obesity: a systematic review and economic evaluation |
Clegg A J, Colquitt J, Sidhu M K, Royle P, Loveman E, Walker A |
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Authors' objectives To assess the clinical and cost-effectiveness of surgery for the management of morbid obesity. A secondary aim was to develop a cost-effectiveness model, using the best available evidence, to determine cost-effectiveness in a UK setting.
Searching Sixteen electronic databases were searched from inception to October 2001 for studies published in English. The search strategy for MEDLINE and the Cochrane Library was provided in the paper. In addition, the references of articles for which full papers were retrieved were checked and industry submissions to the National Institute of Clinical Effectiveness (NICE) were examined.
Study selection Study designs of evaluations included in the reviewSystematic reviews of randomised controlled trials (RCTs), systematic reviews of prospective controlled clinical trials (cohort studies with concurrent controls), RCTs, and prospective controlled clinical trials with a minimum follow-up of 12 months were eligible for inclusion.
Specific interventions included in the reviewStudies that assessed surgical procedures, performed either as open procedures or laparoscopically, and including restrictive procedures such as gastroplasty (vertically banded or silicone ring) and gastric banding, and malabsorptive procedures such as biliopancreatic diversion, Roux-en-Y gastric bypass or jejunoileal bypass, were eligible for inclusion. Most of the included studies compared different surgical procedures; in 3 studies the comparison was with a nonsurgical intervention.
Participants included in the reviewStudies that included participants diagnosed as morbidly obese, defined as a body mass index (BMI) greater than 40 kg/m2, or with BMI less than 35 kg/m2 with serious co-morbid disease, in whom previous nonsurgical interventions had failed, were eligible for inclusion. The majority of the participants in the included studies were women in their late 30s to early 50s.
Outcomes assessed in the reviewStudies that assessed measures of weight change, measures of fat content, measures of fat distribution, quality of life (QoL), peri-and post-operative mortality and morbidity, revision rates, and obesity-related co-morbidities as primary outcomes at baseline and follow-up (minimum 12 months) were included. The length of follow-up in the included studies ranged from 12 months to 5 years, with the majority of studies reporting the latter.
How were decisions on the relevance of primary studies made?One reviewer screened the titles and abstracts, with a second reviewer checking the decisions. Two reviewers then independently examined the full text of selected studies, with any differences being resolved through discussion.
Assessment of study quality The quality of the included studies was assessed using a modified version of the Spitzer criteria (see Other Publications of Related Interest). The studies were assessed according to: methods of randomisation; sampling; sample size; definition of outcome measurements; whether the outcome assessment was double-blind; the use of objective criteria to assess the eligibility of the participants; whether attrition rates were provided; whether the groups were comparable at baseline; and whether the results were generalisable. One reviewer performed the validity assessment and a second reviewer checked it. Any disagreements were resolved by discussion.
Data extraction One reviewer extracted the data and a second reviewer checked them. Any disagreements were resolved by discussion. Data on the results and adverse events were extracted.
Methods of synthesis How were the studies combined?The studies were combined narratively, with the results of all included studies tabulated in full. The studies were grouped according to whether or not the comparator was a surgical intervention and then according to the intervention type. Publication bias was not assessed.
How were differences between studies investigated?Differences between the studies were discussed in relation to the different interventions examined and differences in methodological quality.
Results of the review Eighteen studies (total n=2,009) were included: 17 RCTs (n=1,504) and 1 non-randomised clinical trial (n=505).
The methodological quality of the included studies varied. Out of the nine methodological criteria assessed, 1 trial fulfilled only three, 6 trials fulfilled four, 3 trials fulfilled five, 3 trials fulfilled six, 3 trials fulfilled seven and 2 trials fulfilled eight.
What follows is a summary of the main results of the review. For a more detailed discussion of the results, the reader is referred to the relevant sections of the report.
Surgical interventions versus conventional treatment (2 RCTs and 1 non-randomised clinical trial).
Surgery resulted in a significantly greater weight loss (23 to 37 kg more weight) than conventional treatment. This was maintained at 8 years' follow-up. Although surgery was associated with some worsening of somatic symptoms, other symptoms such as heartburn and joint pain were significantly improved in comparison with nonsurgical interventions. Significant improvements in psychological and social QoL, as well as co-morbidities associated with morbid obesity (particularly hypertension and diabetes), were also observed after surgery. There were no deaths during surgery or in the early post-operative period. However, 2% of surgical patients did require reoperation.
Comparisons of different surgical procedures (15 RCTs).
Comparisons of different types of surgery showed that gastric bypass appeared more beneficial, with a greater weight loss (6 to 14 kg more weight) and/or improvements in co-morbidities compared with either gastroplasty or jejunoileal bypass. It was also associated with fewer complications. Comparisons of open versus laparoscopic gastric bypass and adjustable silicone gastric banding showed fewer serious complications with laparoscopic placement. Although laparoscopic surgery had a longer operation time than open surgery, it resulted in less blood loss, a reduction in the proportion of patients needing to stay in the intensive care unit, and reductions in the length of hospitals stay, days to return to activities of daily living, and days to return to work.
Cost information Yes. The costs of the different interventions varied considerably: from £336 for usual care to £3,223 for vertical banded gastroplasty, £3,333 for open gastric bypass, £3,392 for laparoscopic gastric bypass, and £4,450 and £4,753 for laparoscopic and open silicone adjustable gastric banding, respectively. The total net costs of treating morbid obesity (over 20 years) through surgical procedures ranged from £9,626.90 for vertical banded gastroplasty to £10,795.16 for silicone adjustable gastric banding. All surgical procedures were more costly than treatment through usual care, with total net costs of £36,964.15 over 20 years. The costs were based on several assumptions concerning models of treatment. Authors' conclusions The benefits of surgery for morbid obesity can be classified into three main groups. First, early weight loss resulting in reductions in diabetes and blood pressure, with the effects starting within weeks of surgery. Second, later weight loss leading to improved QoL and reductions in the use of medications. Finally, longer-term health gains from reduced illness such as diabetes and heart disease.
CRD commentary The review question was clearly defined in terms of the interventions, participants, outcomes and study designs. A number of sources were searched for potentially relevant studies, although no efforts were made to identify studies published in languages other than English. Efforts were made to minimise reviewer bias and errors throughout the review process. The quality of the included studies was adequately assessed, and the results of this assessment were used to weight studies in the synthesis. Adequate details of the primary studies were tabulated, and the use of a narrative synthesis was appropriate given the differences between the studies. Overall, the authors' conclusions are consistent with the evidence reviewed and appear robust.
Implications of the review for practice and research Practice: The authors stated that, given the proportions of patients who may benefit from surgery and the need for experienced teams with appropriate facilities, it would seem appropriate that any service should be provided within specialist facilities.
Research: The authors stated that further research addressing the long-term consequences of surgery and its influence on the QoL of patients is required. Economic evaluations comparing the different surgical interventions are also needed.
Funding NHS R&D Health Technology Assessment (HTA) Programme, project number 01/22/01.
Bibliographic details Clegg A J, Colquitt J, Sidhu M K, Royle P, Loveman E, Walker A. The clinical effectiveness and cost-effectiveness of surgery for people with morbid obesity: a systematic review and economic evaluation. Health Technology Assessment 2002; 6(12): 1-153 Other publications of related interest Spitzer WO, Lawrence V, Dales R, Hill G, Archer MC, Clark P, et al. Links between passive smoking and disease: a best-evidence synthesis. Clin Invest Med 1990;13:17-42.
Indexing Status Subject indexing assigned by NLM MeSH Cost-Benefit Analysis; Digestive System Surgical Procedures /economics; Female; Great Britain; Health Services Research; Humans; Male; Obesity, Morbid /complications /epidemiology /surgery; Prevalence; Quality-Adjusted Life Years; Randomized Controlled Trials as Topic; Risk Factors; State Medicine /economics; Treatment Outcome AccessionNumber 12002008532 Date bibliographic record published 31/03/2006 Date abstract record published 31/03/2006 Record Status This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn. |
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