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Cytotoxic drugs and interferons for chronic inflammatory demyelinating polyradiculoneuropathy

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Abstract

Background

Chronic inflammatory demyelinating polyradiculoneuropathy is a disease causing progressive or relapsing and remitting weakness and numbness. It is probably due to an autoimmune inflammatory process. Immunosuppressive or immunomodulatory drugs would be expected to be beneficial.

Objectives

We aimed to review systematically the evidence from randomised trials concerning cytotoxic drugs and interferons for chronic inflammatory demyelinating polyradiculoneuropathy.

Search methods

We searched the Cochrane Neuromuscular Disease Group trials register (searched March 2007), MEDLINE (searched January 1977 to March 2007), EMBASE (January 1980 to March 2007), CINAHL (searched January 1982 to March 2007) and LILACS (searched January 1982 to March 2007). We contacted the authors of the trials identified and other disease experts seeking other published and unpublished trials.

Selection criteria

We sought randomised and quasi‐randomised trials of all immunosuppressive agents such as azathioprine, cyclophosphamide, methotrexate, cyclosporin A, mycophenolate mofetil, and rituximab and all immunomodulatory agents such as alpha interferon and beta interferon in participants fulfilling standard diagnostic criteria for chronic inflammatory demyelinating polyradiculoneuropathy.

Data collection and analysis

Two of us independently selected the trials which met our criteria, judged their methodological quality and extracted the data onto specially designed forms. We wanted to measure the change in disability after one year as our primary outcome measure.

Main results

We found one parallel group open trial of azathioprine for nine months involving 27 participants and another of interferon beta involving 10 participants in a double blind crossover trial with each treatment period lasting 12 weeks. Neither trial provided our primary outcome measure and neither showed a significant beneficial effect on any of the outcome measures selected by the authors or ourselves in the protocol for this review.

Authors' conclusions

The evidence is inadequate to decide whether azathioprine, interferon beta or any other immunosuppressive drug or interferon is beneficial in chronic inflammatory demyelinating polyradiculoneuropathy.

PICOs

Population
Intervention
Comparison
Outcome

The PICO model is widely used and taught in evidence-based health care as a strategy for formulating questions and search strategies and for characterizing clinical studies or meta-analyses. PICO stands for four different potential components of a clinical question: Patient, Population or Problem; Intervention; Comparison; Outcome.

See more on using PICO in the Cochrane Handbook.

Plain language summary

More trials are needed to show whether cytotoxic drugs and interferons are beneficial in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy is an uncommon disease causing progressive or relapsing and remitting weakness and numbness of the arms and legs. It is due to inflammation in the nerves which damages the insulating sheaths (myelin) round individual nerve fibres and in severe cases the actual nerve fibres (axons) themselves. The underlying cause is thought to be an autoimmune response in which the immune cells are misdirected against the myelin. Cochrane reviews have presented evidence that other treatments do help. These are corticosteroids, plasma exchange (in which the abnormal plasma portion of the blood is replaced with a substitute) and intravenous infusions of human immunoglobulin (antibodies extracted from human blood). However, benefit from these treatments is often short‐lived or inadequate and may not occur. Other treatment options include cytotoxic drugs, which kill the cells that might be contributing to the problem. Drugs that regulate the immune system, such as interferons, might also be able to help. There have only been two randomised trials. One was a parallel group open trial of the cytotoxic drug azathioprine for nine months involving 27 participants. The other was a double blind crossover trial of the immune regulating drug, beta interferon , involving 10 participants in with each treatment period lasting 12 weeks. Neither trial showed a significant result but neither was large enough to detect even moderate benefit. Observational studies of these and other drugs, including the cytotoxic drugs cyclophosphamide, cyclosporin A, methotrexate and mycophenolate, and the immune regulating drug alpha interferon have been performed but are insufficient to determine whether any of them are beneficial. Larger trials of beta interferon and methotrexate are in progress.