Preoperative Nutrition in Patients Undergoing Gastrointestinal Surgery.
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
Primary objective
To evaluate if nutritional support intervention by any route prior to surgery improves clinical outcomes for elective GI surgical patients.
Secondary Objectives
To determine if there are any benefits on nutritional intake or nutritional status measurements of nutritional support interventions prior to elective GI surgery.
Background
Description of the condition
Pre‐operative gastrointestinal (GI) surgical patients that are at risk of malnutrition have an increased rate of mortality, morbidity and length of stay (Correira 2003; Barbosa‐Silva 2005; Schiesser 2009). When the nutritional status of GI surgical patients has been evaluated prior to surgery 14% elective admissions were found to be at risk nutritionally, of which 40% suffered post‐operative complications, and this was significantly greater than for those who were well nourished (Schiesser 2008). In elective GI surgical patients it has been observed that 9% had body mass index indicating under nutrition, although 54% had lost weight unintentionally in the six months prior to surgery and 17% had lost more than 10% of their body weight in the same period, which is clinically significant (Fettes 2002). Malnutrition is a well recognised problem in GI surgical patients and in a recent UK survey 40% of patients with GI disease were reported to be at risk of malnutrition compared to 28% of all hospital admissions (Russell 2008). It has been demonstrated that poor nutritional status detrimentally affects post‐operative outcome in colorectal surgical patients (Schwegler 2010). In prospective studies that have evaluated nutritional intervention in surgical patients some positive effects have been demonstrated for the use of enteral nutrition (Beier‐Holgersen 1996) and for oral sip feeds post‐operatively (Keele 1997). In a consensus review of Enhanced Recovery After Surgery (ERAS) it is recommended that patients receive carbohydrate loading 24 hours pre‐operatively and nutritional supplements are prescribed from the day of surgery until oral intake is achieved (Lassen 2009). In the period prior to hospital admission or more than 24 hours pre‐operatively there is a lack of consensus regarding the provision of nutritional support for weight losing patients or those who are malnourished.
Description of the intervention
Nutrition support intervention includes nutritional formulations that are used for medical purposes administered via the oral, enteral or parenteral route. For this review nutritional support intervention is referring to mixed formulas containing macro and micronutrients with or without immunomodulating components.
How the intervention might work
The presence of malnutrition can contribute to a poor clinical outcome by affecting body structure, function, physical and psychological health (Stratton 2003). Malnutrition has been shown to be a significant prognostic indicator for post‐operative complications (Sungurtekin 2004; Sorensen 2008), which significantly increase length of hospital stay (Leung 2009). Correcting malnutrition pre‐operatively in surgical patients to decrease post‐operative morbidity and mortality would logically, therefore be potentially beneficial. When nutritional support has been instigated in malnourished patients positive effects on clinical outcomes, anthropometry and cost effectiveness have been demonstrated (Smedley 2004; Beier‐Holgersen 1996). Benefits from the provision of nutritional intervention have also been demonstrated in well nourished cohorts and without any direct effect on nutritional status measurements. This implies that there are physiological benefits to nutrition intervention without improvements in anthropometric measurements, which include improved immune, respiratory and cardiac function along with improved wound healing and mobility (Akbarshahi 2008; Clark 2000).
Why it is important to do this review
ERAS is becoming increasing common in the management of GI surgical patients. ERAS includes recommendations on post‐operative nutritional management and feeding with pre‐operative carbohydrate loading (Lassen 2009). However, there is no consensus regarding nutritional intervention in the period preceding hospital admission for patients admitted for elective GI surgery.
Objectives
Primary objective
To evaluate if nutritional support intervention by any route prior to surgery improves clinical outcomes for elective GI surgical patients.
Secondary Objectives
To determine if there are any benefits on nutritional intake or nutritional status measurements of nutritional support interventions prior to elective GI surgery.
Methods
Criteria for considering studies for this review
Types of studies
Published randomised controlled trials, conference abstracts of RCTs where sufficient data can be obtained.
Types of participants
All non‐ emergency GI surgical patients.
Types of interventions
Nutrition support intervention by any route using any nutritional formulation containing both macro and micronutrients. Studies will be included if the nutritional formulation has a carbohydrate, fat and nitrogen source with vitamins and minerals administered over any time, (up to 24 hours pre‐operatively and 3 months prior to surgery). Studies will be included if they have manipulated dietary intake to increase calories and protein. Studies will be excluded if they are evaluating a single nutrient or immuno enhancing agent or any combination of nutritional components that do not meet the inclusion criteria.
Types of outcome measures
Primary outcomes
1. Complications
Infective ‐ Including pneumonia, wound infections, abdominal abscess.
Non‐infective ‐ Including anastomotic leak, wound dehiscence, organ failure or thromboembolism
2. Length of hospital stay
Secondary outcomes
1. Nutritional aspects including weight, anthropometric measurements, hand grip strength and subjective global assessment
2. Quality of life (including patient reported outcomes)
3. Within group and between group changes in macro nutrient (calories and protein/nitrogen) intake
4. Biochemical parameters including albumin, prealbumin and C reactive protein
5. 30 day perioperative mortality
6. Adverse effects from feed and route of feeding
All outcomes will be included up to 3 months post‐operatively
Search methods for identification of studies
Electronic searches
We will identify RCTs by searching a number of databases including all EBM Reviews (Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA and NHSEED) MEDLINE, EMBASE, AMED, British Nursing Index Archive using OvidSP to run a search on each database separately then exclude duplicates. Detailed search strategy is shown in Appendix 1.
Searching other resources
Will hand search the reference lists of the articles selected for the review and contact authors of any conference abstracts if further data are required.
Data collection and analysis
Selection of studies
Two review authors will assess the title and abstract to determine relevance and eligibility. We will exclude all papers failing to meet the eligibility criteria. If there is insufficient information in the title and abstract the article will be obtained for clarification. The review authors will assess the full text of all the papers and extract data from those studies meeting the inclusion criteria. We will translate any non‐English articles before assessment if needed. A third review author will be called upon to resolve any conflicts in study selection.
Data extraction and management
A data collection form will be devised that will facilitate the data collection from the articles. This form will allow eligibility to be assessed by linking the studies directly to the research question. The data extraction form will be piloted and modified as required. Two reviewers will undertake the process of data extraction independently and any discrepancies discussed with a third review author. For each trial the following information will be recorded.
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Year of publication, country of origin, source of funding and number of participants.
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Details of participants including proportion of malnourished patients (using body Mass index less than 20kg/m2, weight loss greater than 10% in the previous 3‐6 months, subjective global assessment or nutrition risk derived from a validated tool).
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Number of participants, age, type of surgery, perioperative management ERAS or traditional, gender, diagnosis (noting proportion of cancer and non cancer diagnosis).
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Details of type intervention (nutritional substrate with or without immune enhancing agents), route of intervention (oral, enteral or parenteral) and length of time on intervention, daily volume of nutritional substrate delivered.
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Details of primary and secondary outcomes.
Assessment of risk of bias in included studies
We will rate the quality of each trial in the following areas; random sequence generation, allocation concealment, blinding, complete outcome data, selective outcome reporting and other sources of bias using the Cochrane Collaboration's tool New Reference.
Measures of treatment effect
The estimates of effect of an intervention will be expressed as risk ratios together with 95% confidence intervals.
Unit of analysis issues
For dichotomous outcomes, estimates of effect of an intervention will be expressed as risk ratios together with 95% confidence intervals. Continuous outcomes will be expressed using mean differences and standard deviations to summarise the data for each group.
Dealing with missing data
Authors will be contacted for abstracts and missing data will be obtained from authors where possible.
Assessment of heterogeneity
Clinical heterogeneity will be assessed by examining the type of participants, interventions and outcomes in each study. Meta‐analyses will only be conducted if there are studies reporting similar comparisons for the outcome measures.
Assessment of reporting biases
To evaluate reporting bias funnel plots will be used if appropriate.
Data synthesis
Meta‐analyses will only be conducted if there are studies reporting similar comparisons for the same outcome measures.
Subgroup analysis and investigation of heterogeneity
Sub group analysis will be undertaken on studies including malnourished participants, cancer and non cancer participants, elective versus semi‐elective surgery, those that state the use of an ERAS protocol and route of feeding if data allow.
Sensitivity analysis
Planned sensitivity analysis will be undertaken to examine the difference in the quality of the studies and to examine the difference in studies conducted before and after 1990. This cut date is used because there have been advances in artificial feeding since 1990, including changes in technology, line care, feeding tubes and monitoring. The type and amount of enteral and parenteral nutrition delivered has also changed considerable. Also sensitivity analysis will be conducted on studies that use an ERAS protocol.
