This is a critical abstract of an economic evaluation that meets the criteria for inclusion on NHS EED. Each abstract contains a brief summary of the methods, the results and conclusions followed by a detailed critical assessment on the reliability of the study and the conclusions drawn.

The use of laparoscopy-assisted colectomy (LAC) for the treatment of complex sigmoid polyps (CSP). The surgical strategy was chosen according to tumour location. Surgery could be either extracorporeal bowel resection and anastomosis (if the tumour was located more than 20 cm above the anal verge), or medial-to-lateral dissection (if the tumour was located 15 to 20 cm above the anal verge).

Treatment.

Cost-effectiveness analysis.

The study population comprised patients with a diagnosis of CSP (i.e. large sessile or pedunculated benign polyps or malignant polyps that could not be safely or adequately removed by colonofibroscopy, and required surgical intervention).

The setting was a hospital. The study was carried out in Taipei, Taiwan.

The effectiveness and resource use data were collected between January 1997 and December 1999. The price year was not reported.

The effectiveness data were derived from a single study.

The costing appears to have been performed in the same sample population as that used in the effectiveness analysis. The data used may have been collected both prospectively and retrospectively, as a standardised questionnaire was used to collect some data that might have been used in the estimation of costs.

No sample size calculations appear to have been performed in the planning phase of the study in order to assure a certain power. All the patients who were diagnosed with CPS in the Department of Colorectal Surgery (National Taiwan University Hospital), where the study was carried out, were considered for the clinical analysis. Forty-two patients were recruited during the study period and randomised to one of the study groups, 21 to LAC group and 21 to LSBR. The authors did not report any evidence that the study sample was representative of the study population.

This was an open-label, randomised controlled trial that was performed at a single centre. A block randomisation method was used to allocate the patients to the study groups. The authors did not clearly report the follow-up period for the patients, although data were collected from the moment of the surgical intervention to the point at which patients were able to return to work (on average, less than 2 months). Three of the LAC patients withdrew from the study after randomisation, but before the intervention was performed, and sought open surgery at other hospitals. Research assistants blinded to the study groups evaluated some but not all of the outcomes.

The basis for the effectiveness analysis was "treatment completers only", involving 18 LAC patients and 21 LSBR patients. The primary health outcomes used to assess both interventions (LAC and LSBR) were:

the number of hours with postoperative ileus;

postoperative pain, as evaluated by scores on a visual analogue scale (VAS);

the length of operative bound;

the number of patients experiencing postoperative complications (i.e. fever, wound infection, urinary tract infection, anastomotic leakage and myocardial infarction); and

the disability, in terms of the number of weeks required to return to partial activity, return to full activity and return to work.

The severity of surgical insult was evaluated as the coefficient between the postoperative and the preoperative values for several immunological parameters. More specifically, the serum C-reactive protein concentration (CRP), the erythrocyte sedimentation rate (ESR), blood lymphocyte counts and the CD4+/CD8+ ratio. Data were presented as the mean +/ the standard deviations (SD). There were no statistically significant differences between the study groups in terms of age, gender, symptoms, tumour location, localisation method, tumour size, morphology of the CPS, histopathology and accuracy of clinical diagnosis.

LAC patients presented a significantly lower number of hours with postoperative ileus than LSBR patients (48.0 +/ 12.5 hours versus 96.0 +/ 18.4 hours; p<0.05).

The VAS scores for postoperative pain were significantly lower for LAC patients than for LSBR patients (4.2 +/ 1.0 versus 8.5 +/ 1.2; p<0.05).

The length of the operative bound was significantly smaller for LAC patients (4.5 +/ 0.5 cm versus 12.8 +/ 2.0 cm; p<0.05).

There was a significantly smaller number of LAC patients experiencing postoperative complications (1 with postoperative fever) than LSBR patients (2 with postoperative fever, 2 with wound infection, 1 with urinary tract infection, 1 with anastomotic leakage and 1 with myocardial infarction; p<0.05).

Patients in the LAC group required significantly less time than LSBR patients before returning to partial activity (2.0 +/ 0.4 weeks versus 3.0 +/ 0.4 weeks), full activity (4.0 +/1.0 weeks versus 6.0 +/ 0.7 weeks), and work (4.1 +/ 0.3 weeks versus 6.0 +/ 1.0 weeks), (p<0.05).

Compared with LBSR patients, LAC patients showed a significantly lower surgical stress in terms of significantly lower CRP and ESR coefficients, and higher lymphocyte counts and CD4+/CD8+ ratio, (p<0.05).

LAC patients experienced significantly lower pain, fewer postoperative complications, less postoperative stress, and quicker recovery than LSBR patients.

No summary measure of benefit was used in the economic analysis. The study was therefore categorised as a cost-consequences analysis.

The categories of the direct costs included in the economic evaluation were not identified. They might have corresponded to a hospital perspective. Some of the resource quantities were reported separately, but the unit costs used to value them were not given. The sources used to collect the unit cost data were not provided. Therefore, it could not be stated whether the costs were estimated entirely from actual data, or whether some guesses were also made. The price year was not identified. Discounting was not performed, although it was not relevant as a period shorter than 2 years was considered for the economic evaluation. The estimated costs were the average cost per patient for each of the interventions.

The costs were treated stochastically since some of the mean and SDs of the resource quantities and the final costs were reported. The authors reported that a two-tailed Fisher's exact test was used to analyse the categorical data, while Student's t test was used to compare the continuous data.

The indirect costs were not reported.

New Taiwan Dollars (NT$). The authors reported an approximate exchange rate $1 = NT$31.

No sensitivity analyses were reported.

See the 'Effectiveness Results' section.

The average cost per patient was significantly higher for LAC patients (mean NT$188,612, SD 8,105) than for LSBR patients (mean NT$180,354, SD 9,654), (p<0.05).

It could not be inferred whether the costs of treating adverse effects were included in the cost estimation, though they were relevant.

Since a cost-consequences analysis was undertaken, the estimated health benefits and costs were not combined.

The authors reported that the incremental cost of performing LAC instead of LSBR was $266.39 (p<0.05).

The results of this study demonstrated that laparoscopy-assisted colectomy (LAC) can be safely applied to the treatment of complex sigmoid polyps (CSP) with less operative stress and quicker recovery of patients, although it was significantly more expensive than laparotomy with segmental bowel resection (LSBR).

A justification was given for the comparator chosen. LSBR is a traditional used health technology for the treatment of CSP. You should decide if this is a widely used health technology in your own setting.

The study was based on an open randomised controlled trial, which was appropriate for the study question (given the difficulties in performing this type of surgical intervention). Block randomisation was used, which allowed both study groups to be kept comparable at analysis. The authors reported that the randomisation was performed preoperatively and not intraoperatively (as would have been desirable). This led some patients to withdraw from the study. A treatment completers only analysis was performed, and it is not clear whether the results may have been biased as a result (since a rather small sample size was considered for the study). It would appear that the results of this study are internally valid. Since the authors did not report any evidence that the study sample was representative of the study population, it cannot be stated whether the study findings are externally valid.

No summary measure of health benefit was used in the economic analysis. The study was therefore categorised as a cost-consequences analysis.

Since the categories of costs included in the cost estimation were not identified, it was not possible to recognise the perspective adopted for the economic analysis. This introduced considerable uncertainty into the cost estimation, and would make the extrapolation of results to other settings difficult. Some of the resource quantities used were reported separately. Means and SDs for these and for the final costs were provided, which reduced some of the uncertainty surrounding the cost estimation. The price year was not reported, which will limit any future inflation exercises. Discounting was not performed, which was appropriate since the period considered for the estimation of costs was less than 2 years.

The authors did not make appropriate comparisons of the study findings with those from other studies. The issue of the generalisability of the results to other settings was not addressed. The study enrolled patients with a diagnosis of CSP and this was reflected in the authors' conclusions. The authors did not report any further limitations of the study.

The authors suggested that the results encourage the use of LAC in the treatment of CSP if the patient's economic status permits (the equipment-related costs of laparoscopic surgery were not covered by National Health Insurance in Taiwan).

The authors recommended that the following aspects be considered before extensive application of LAC:

the intervention requires an experienced surgeon to perform it safely and with minimal invasiveness on the patients;

the choice of the surgical strategy depends on tumour location; and

there is some risk that a complex polyp may hide a malignancy.

As the authors commented, this study could provide a basis for conducting ongoing clinical trials on the application of this technique to benign and even malignant lesions located in other parts of the colon.

None stated.

Okuda J, Tanigawa N. Colon carcinomas may be adequately treated using laparoscopic method. Seminars in Colon and Rectal Surgery 1998;9:2416.

Wexner SD, Johansen OB. Laparoscopic bowel resection: advantages and limitation. Annals of Medicine 1992;24:10510.