Systematic reviews and meta-analyses: the value for surgery

Glutamine dipeptide for parenteral nutrition in abdominal surgery: A meta-analysis of randomized controlled trials

AIM: To assess the clinical and economical validity of glutamine dipeptide supplemented to parenteral nutrition (PN) in patients undergoing abdominal surgery.

METHODS: A meta-analysis of all the relevant randomized controlled trials (RCTs) was performed. The trials compared the standard PN and PN supplemented with glutamine dipeptide in abdominal surgery. RCTs were identified from the following electronic databases: the Cochrane Library, MEDLINE, EMBASE and ISI web of knowledge (SCI). The search was undertaken in April 2006. Literature references were checked by computer or hand at the same time. Clinical trials were extracted and evaluated by two reviewers independently. Statistical analysis was performed by RevMan4.2 software from Cochrane Collaboration. A P value of < 0.05 was considered statistically significant.

RESULTS: Nine RCTs involving 373 patients were included. The combined results showed that glutamine dipeptide has a positive effect in improving postoperative cumulative nitrogen balance (weighted mean difference (WMD = 8.35, 95% CI [2.98, 13.71], P = 0.002), decreasing postoperative infectious morbidity (OR = 0.24, 95% CI [0.06, 0.93], P = 0.04), shortening the length of hospital stay (WMD= -3.55, 95% CI [-5.26, -1.84], P < 0.00001). No serious adverse effects were found.

CONCLUSION: Postoperative PN supplemented with glutamine dipeptide is effective and safe to decrease the infectious rate, reduce the length of hospital stay and improve nitrogen balance in patients undergoing abdominal surgery. Further high quality trials in children and severe patients are required, and mortality and hospital cost should be considered in future RCTs with sufficient size and rigorous design.

Converted laparoscopic colorectal surgery

BACKGROUND

Conversion rates following laparoscopic colorectal surgery vary widely between studies, and the outcome of converted patients remains controversial.

METHODS

A comprehensive search of the English-language literature was updated until May 1999.

RESULTS

Twenty-eight studies on 3232 patients were considered for analysis. The overall conversion rate was 15.38%. Seventy nine percent of the studies did not include a definition for conversion; in these studies, the conversion rate was significantly lower than in the series where a specific definition was considered (13.7% vs 18.9%, chi-square test, p < 0.001). Converted patients had a prolonged hospital stay (11.38 vs 7.41 days) and operative time (209 vs 189 min) in comparison with laparoscopically completed patients (95% confidence interval (CI), 1.70-4.00 and 35.90-37.10, respectively). The factors associated with an increased rate for conversion were left colectomy (Odds Ratio [OR] = 1.061), anterior resection of the rectum (OR = 1.088), diverticulitis (OR = 1.302), and cancer (OR = 2.944) (for each parameter, Wald chi-square value, p < 0.001).

CONCLUSIONS

In nonrandomized studies, the rate of laparoscopically completed colorectal resections is close to 85%. Because converted patients have a distinct outcome, a clear definition of conversion is required to compare the results of randomized trials. Such trials should also consider a 20% rate of conversion when estimating the sample size for the desired power level. It is likely that converted patients will have a significant impact on the results of future clinical research in laparoscopic colorectal surgery.

The effectiveness of growth hormone, glutamine and a low-fat diet containing high-carbohydrate on the enhancement of the function of remnant intestine among patients with short bowel syndrome: a review of published trials

Many patients who undergo extensive resection of the gastrointestinal tract develop malabsorption which, in the worst cases, requires long-term parenteral nutrition at home, frequently on a permanent basis. Such patients can be defined as having intestinal failure resulting from the short bowel syndrome. In 1995, Wilmore's group hypothesized that the administration of growth factors and nutrients could enhance further adaptation of the remnant intestine and thereby improve absorption. The demonstrated, through controlled clinical trials, the benefit of such treatment among 47 adults with less than 200 cm of small intestine. Over the past few years, similar trials as well as animal experiments have been conducted by the same authors and other groups with conflicting results. We have performed a systematic search on the electronic databases for the purpose of identifying the evidence published so far on this subject. Our analysis suggests that the benefit of administering recombinant human growth hormone alone, or together with glutamine with or without a low-fat diet containing high-carbohydrate (fibre) is, if any, marginal.

Somatostatin and octreotide in the prevention of postoperative pancreatic complications and the treatment of enterocutaneous pancreatic fistulas: a systematic review of randomized controlled trials

BACKGROUND

The aim of this study was to evaluate, through systematic review, the effectiveness of somatostatin and octreotide in the prevention of postoperative pancreatic complications and the treatment of established enterocutaneous pancreatic fistulas.

METHODS

Electronic databases, including Medline and EMBASE, were searched systematically by using keywords including 'somatostatin', 'octreotide', 'fistula' and 'randomiz(s)ed controlled trial'. In addition, citations of relevant primary and review articles were examined. Particular authors were contacted when necessary. Data on patient recruitment, intervention and outcome were extracted from the included trials and analysed.

RESULTS

Use of somatostatin or octreotide for the prevention of postpancreatectomy complications, including pancreatic fistulas, was identified in 14 randomized controlled trials, including one abstract and one conference proceeding, involving a total of 1686 patients. Use of somatostatin or octreotide for the treatment of established enterocutaneous pancreatic fistulas was identified in ten trials involving a total of 301 patients. Significant heterogeneity was found among the identified trials with regard to the definition of fistula, dosage of octreotide, starting time and duration of the treatment, among other factors.

CONCLUSION

There was major disagreement between the studies on whether use of the drugs in question is of value in preventing postoperative complications. This analysis suggests that, in units where the postoperative fistula rate following pancreaticoduodenectomy for neoplasia and other pancreatic conditions exceeds 10 per cent, somatostatin or octreotide administered before operation may significantly reduce the rate of major postoperative complications, particularly pancreatic fistulas. The identified evidence also suggests that there may be a limited role for such drugs in the treatment of established postoperative enterocutaneous pancreatic fistulas. A major conclusion is that further clarification of the roles of these drugs is still required through large, high-quality, randomized trials.

Systematic review of antimicrobial agents used for chronic wounds

BACKGROUND

This paper is one of a series of eight systematic reviews that aim to identify effective interventions for chronic wounds. Here, antimicrobial agents are evaluated.

METHODS

Electronic databases and other relevant sources were accessed to identify published and unpublished material. Studies were eligible for inclusion if they used concurrent controls, recruited participants with chronic wounds, evaluated an intervention designed to prevent or treat chronic wounds, and incorporated an objective assessment of wound healing. All included studies were assessed against a comprehensive checklist for methodological quality. A narrative overview was conducted.

RESULTS

Thirty trials were included, 25 of randomized design. Small sample size and other methodological problems meant that findings were often difficult to interpret. Results do not support the routine use of systemic antibiotics for leg ulcers or diabetic foot ulcers without acute infection, but they may be useful as an adjunct to surgery for pilonidal sinuses. Several topical preparations may be helpful, including dimethyl sulphoxide, silver sulphadiazine, benzoyl peroxide, oxyquinoline and gentamicin.

CONCLUSION

Most of this research requires replication in larger, well designed studies to establish both clinical and cost effectiveness.

Hepatic resection for colorectal liver metastases: A cost-effectiveness analysis

OBJECTIVE

To analyze the cost-effectiveness of resection for liver metastases compared with standard nonsurgical cytotoxic treatment.

SUMMARY BACKGROUND DATA

The efficacy of hepatic resection for metastases from colorectal cancer has been debated, despite reported 5-year survival rates of 20% to 40%. Resection is confined to specialized centers and is not widely available, perhaps because of lack of appropriate expertise, resources, or awareness of its efficacy. The cost-effectiveness of resection is important from the perspective of managed care in the United States and for the commissioning of health services in the United Kingdom.

METHODS

A simple decision-based model was developed to evaluate the marginal costs and health benefits of hepatic resection. Estimates of resectability for liver metastases were taken from UK-reported case series data. The results of 100 hepatic resections conducted in Sheffield from 1997 to 1999 were used for the cost calculation of liver resection. Survival data from published series of resections were compiled to estimate the incremental cost per life-year gained (LYG) because of the short period of follow-up in the Sheffield series.

RESULTS

Hepatic resection for colorectal liver metastases provides an estimated marginal benefit of 1.6 life-years (undiscounted) at a marginal cost of 6,742 pound sterling++. If 17% of patients have only palliative resections, the overall cost per LYG is approximately 5,236 pound sterling (5,985 pound sterling with discounted benefits). If potential benefits are extended to include 20-year survival rates, these figures fall to approximately 1,821 pound sterling (2,793 pound sterling with discounted benefits). Further univariate sensitivity analysis of key model parameters showed the cost per LYG to be consistently less than 15,000 pound sterling.

CONCLUSION

In this model, hepatic resection appears highly cost-effective compared with nonsurgical treatments for colorectal-related liver metastases.

Debate: Albumin administration should not be avoided

The recent Cochrane report on albumin administration is analysed and criticised on the grounds of clinical methodology, content and interpretation. Although it is naïve and illogical to treat hypoalbuminaemia with albumin infusions, a more balanced view on the use of albumin for resuscitation in acute hypovolaemia is necessary. Once the acute phase of critical illness is past, interstitial volume is often expanded causing oedema, with a low plasma volume. We argue for the use of salt-poor albumin solutions in this situation and conclude that, on current evidence, the assertion that albumin should be avoided in all situations is irrational and untenable.