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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

The clinical and cost-effectiveness of pulsatile machine perfusion versus cold storage of kidneys for transplantation retrieved from heart-beating and non-heart-beating donors

J Wight, J Chilcott, M Holmes, and N Brewer.

Review published: 2003.

Link to full article: [Journal publisher]

CRD summary

This poorly reported review assessed machine perfusion versus cold storage for the preservation of kidneys prior to transplantation. Machine perfusion was associated with a reduction in the incidence of delayed graft function, but with no impact on long-term graft survival. The authors highlighted that this finding was based on poor quality research, with much of it relating to outdated technologies.

Authors' objectives

To evaluate the clinical effectiveness and cost-effectiveness of machine perfusion (MP) versus cold storage (CS) for the preservation of kidneys prior to transplantation. The review also examined whether the use of MP could allow valid testing of kidney viability prior to transplantation.

Searching

A total of 15 electronic databases were searched from their inception to 2001; these were listed in the review. In addition, the reference lists of relevant articles and reviews were checked and various health services research-related resources were consulted via the Internet; these were also listed. No language restrictions were imposed.

Study selection

Study designs of evaluations included in the review

Studies of all comparative designs (randomised or not) were eligible for inclusion in the evaluation of the relative clinical effectiveness of MP and CS. Most of the studies involved pairs of kidneys studied together, one preserved by MP and the other by CS. The method of allocating the kidney to the recipient was unclear.

Specific interventions included in the review

Studies that compared the success of kidneys preserved by MP with those preserved by CS were eligible for the review. The included studies had investigated a range of CS duration and various solutions and techniques (details were given. Similarly, the studies had used various machines for MP with a range of solutions and preservation times (details were given). Some of the studies used a combination of CS and MP.

Participants included in the review

For the evaluation of the relative clinical effectiveness of MP and CS, only studies that were of patients undergoing kidney transplantation were to be included. Studies of transplantation involving kidneys from both live and non-heart-beating donors were eligible for the review. The total number of patients undergoing transplants in all included studies was unclear.

Outcomes assessed in the review

The outcomes of interest were delayed graft function (DGF) and some measure of longer term survival. The most commonly reported outcome in the included studies was some measure of immediate graft function; this was usually the requirement for dialysis in the first week post-transplantation. DGF or the presence of acute tubular necrosis was also reported. Some studies reported longer term survival, more specifically 1-year graft survival.

How were decisions on the relevance of primary studies made?

The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.

Assessment of study quality

The quality of the included studies for the evaluation of the relative clinical effectiveness of MP and CS was assessed according to the Jadad scale. One reviewer undertook the quality assessment and a second review checked it. Any disagreements were resolved by discussion.

Data extraction

One reviewer undertook the data extraction and a second review checked it. Any disagreements were resolved by discussion. Data on the incidence of DGF or long-term graft survival were extracted and used to derive the relative risks (RRs). Data on viability were extracted as reported in each individual study.

Methods of synthesis

How were the studies combined?

The studies in the evaluation of the relative clinical effectiveness of MP and CS were combined in a narrative review, supplemented by a meta-analysis of two outcome measures: DGF and 1-year survival. The meta-analysis was performed using a random-effects model (DerSimonian and Laird) to obtain the pooled RR with a 95% confidence interval (CI). Publication bias was assessed using funnel plots.

How were differences between studies investigated?

The meta-analyses were performed on groups of studies, as appropriate due to study heterogeneity. Statistical heterogeneity within the meta-analyses was investigated using a chi-squared test. The results of the heterogeneity test were not reported in the review.

Results of the review

Twenty comparative studies were included in the review of the evaluation of the relative clinical effectiveness of MP and CS. Only in one of these was the allocation properly randomised.

Evaluation of the relative clinical effectiveness of MP and CS.

The quality of the included studies was generally very poor: only four studies scored 2 out of 5, seven scored 1 and nine scored 0.

Fifteen studies (1,154 kidneys or patients) were combined in the meta-analysis of DGF. The results suggested a 20% reduction in DGF with MP compared with CS (pooled RR 0.804, 95% CI: 0.672, 0.961, P=0.017). It was unclear from the review whether or not this was subject to heterogeneity (value not reported), although the authors stated that they conducted subgroup meta-analyses because of heterogeneity. The results of the subgroup analyses follow; whether there was any heterogeneity in these pooled studies was not reported.

Non-heart-beating donors (3 studies): there was no significant difference between MP and CS in the incidence of DGF (RR 0.847, 95% CI: 0.653, 1.098, P=0.21).

Heart-beating donors (5 studies): there was a statistically significant reduction in DGF with MP compared with CS (RR 0.718, 95% CI: 0.572, 0.903, P=0.005).

Donor status not specified (number of studies not stated): there was no significant difference between MP and CS in the incidence of DGF (RR 0.865, 95% CI: 0.587, 1.275, P=0.46).

Use of University of Wisoconsin solution as perfusate (2 studies): there was a statistically significant reduction in DGF with MP compared with CS (RR 0.703, 95% CI: 0.524, 0.943, P=0.019).

Studies of second and subsequent transplant (5 studies): the was no significant difference in DGF with MP compared with CS (RR 0.863, 95% CI: 0.667, 1.116, P=0.26).

All of the studies with a mean ischaemia time of greater than 24 hours reported a RR of less than 1 for DGF.

Seven studies (420 patients) were combined in the meta-analysis of 1-year graft survival. There was no difference between MP and CS (pooled RR 1.025, 95% CI: 0.963, 1.090, P=0.44); no heterogeneity was reported.

Can the use of MP allow valid testing of kidney viability prior to transplantation?

Eighteen studies were reported for this part of the review. Overall, there was little evidence that non-viable kidneys can be accurately identified when on MP. Further details were provided.

Cost information

Economic modelling was used to determine the cost-effectiveness and cost-utility of MP. It is unlikely that, in the UK health setting, complete cost recovery will be obtained from a reduction in the incidence of DGF. The probability that MP is cheaper and more effective than CS in the long term was estimated to be around 80% for non-heart-beating donor recipients and 50 to 60% for heart-beating donor recipients.

Authors' conclusions

The limited evidence available (based on poor-quality research, much with outdated technologies) indicated that MP is associated with a 20% reduction in the incidence of DGF, but it has no impact on long-term graft survival. Overall, there was little evidence that non-viable kidneys could be accurately identified when on MP.

CRD commentary

The review addressed two clear research questions relating to organ preservation for kidney transplantation. However, the inclusion criteria for the review, and much of the review methodology, were not well reported. The literature search was thorough, but the selection criteria and methods used for synthesis could only be assumed from the results. Thus, the reader cannot be certain that the review was not subject to reviewer and other biases. The data extraction and quality assessment were performed with independent checking and the results of these processes were presented clearly in the review.

The interpretation of the results of the meta-analyses is hampered by the authors' failure to report the results of the heterogeneity test. In addition to the limitations in the reporting of the review, the conclusions that can be drawn are limited by the poor quality and clinical heterogeneity of the primary data, much of which were based on outdated technologies. This was acknowledged by the review's authors.

Implications of the review for practice and research

Practice: The authors stated that MP is associated with a 20% reduction in the incidence of DGF, but it has no impact on long-term graft survival.

Research: The authors stated that a definitive study of the clinical and economic benefit of MP needs to be undertaken. Research is needed to develop a valid test of kidney viability.

Funding

NHS R&D Health Technology Assessment (HTA) Programme, project number 01/35/01.

Bibliographic details

Wight J, Chilcott J, Holmes M, Brewer N. The clinical and cost-effectiveness of pulsatile machine perfusion versus cold storage of kidneys for transplantation retrieved from heart-beating and non-heart-beating donors. Health Technology Assessment 2003; 7(25): 1-94. [PubMed: 14499050]

Other publications of related interest

Wight JP, Chilcott JB, Holmes MW, Brewer N. Pulsatile machine perfusion vs. cold storage of kidneys for transplantation: a rapid and systematic review. Clin Transplantation 2003;17:293-307.

Indexing Status

Subject indexing assigned by NLM

MeSH

Cell Survival; Cost-Benefit Analysis; Cryopreservation; Graft Rejection; Graft Survival; Humans; Kidney /cytology; Kidney Transplantation /economics; Organ Preservation /methods; Organ Preservation Solutions; Pulsatile Flow; Tissue Donors

AccessionNumber

12003008637

Database entry date

30/11/2004

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.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 14499050

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