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Effective Intervention

Background

Dermatomyositis occurs infrequently, with an incidence probably less than 1 per 300,000 per year. It is characterised by an intramuscular microangiopathy mediated by a complement membrane attack complex. There is a loss of muscle capillaries, muscle ischaemia, muscle-fibre necrosis and perifascicular atrophy.

There is an unmistakable rash with purplish appearance on the eyelids, cheeks and light exposed areas. A rash is often seen on the extensor surfaces of knees, elbows and knuckles, and this becomes scaly.

Treatment is usually with steroids, but cytotoxic drugs and immunosuppressants are also added. Many patients do not respond to this treatment and remain physically disabled.

RCT shows startling results

A very well conducted double-blind placebo-controlled randomised control trial of high dose immune globulin has shown that it is an effective treatment. The study from the NIH in Bethesda looked at fifteen patients with therapy resistant dermatomyositis. Patients were block randomised to immune globulin infusion or placebo by disease severity, and they continued on their normal therapy during the study. Immune globulin was infused at 2g/kg body weight, with one infusion each month.

Treatment was for three months, followed by cross-over after a one month washout. Patients were followed for three months after the end of the study before codes were broken.

Response was assessed by neuromuscular symptom scale, the ADL scale, a scale to measure muscle strength and repeated muscle biopsies.

The results were excellent. Of 12 patients treated with immune globulin, 9 had major improvements, 2 had mild improvement and only one had no change. Placebo had no such effect. No unwanted effects were reported with immune globulin infusion.

Muscle biopsies after immune globulin treatment showed an increase in the diameter of muscle fibres, and regenerating muscle fibres became sparse. There was an increase in the number of capillaries and decrease in their diameter, and the ratio of muscle fibres to capillaries returned almost to normal.

Patients back to normal

Perhaps the simplest way of conveying a complex set of objective scale results is to quote from the paper: Speaking of five patients with severe muscle weakness the authors said that "these patients had not felt so strong since the onset of their disease .....Those using wheelchairs were able to get up, run, climb stairs and behave normally."

After the study patients actively sought to obtain continued immune globulin treatment. Six managed to obtain it, and require an infusion approximately every six weeks.

High dose infused immune globulin was effective in treating therapy-resistant dermatomyositis. Patients who were previously disabled returned to normal life.

Cost implications

Treatment for an individual patient at 2g immune globulin every six weeks would be expensive - approaching £20,000 per year. There are very few patients, however. That can, however, be balanced by reduction in other drugs, some, of which are expensive. In addition, the very significant reduction in disability in these patients, enabling many to lead normal lives, would have concomitant economic benefits.

Reference:

Dalakas et al. New England Journal of Medicine 1993 329: 1993-2000.

Questions to be Answered

Q: What need is met by this treatment?
A: Disabled patients with dermatomyositis can be returned to normal life.
Q: What happens at present?
A: Patients are treated with steroids, immunosuppressant and cytotoxic drugs. Many do not respond.
Q: How does the treatment improve effectiveness?
A: Patients resistant to standard therapy can achieve normal life. Intravenous immune globulin therapy can be given at home.
Q: What is the capital cost?
A: None.
Q: What is the treatment cost per case?
A: About £20,000 per year.
Q: Will this increase the total cost of care?
A: Not known. There is a balance between high cost of immune globulin treatment, to be offset against reduced cytotoxic and immunosuppressant drugs, as well as reduced care costs and the economic benefits of returning a disabled patient to health.

Advice to purchasers

  • Will increase quality and effectiveness.
  • Will probably increase total costs.
  • Should consider inclusion in specification for intravenous immune globulins for as part of longer term development of clinical immunology services.
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