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Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a rare and disabling immune neuropathy which often has a heterogeneous presentation. Patients usually improve after therapy with steroids, high-dose intravenous immunoglobulin (IVIg) or plasma exchange. Most patients require, however, a prolonged treatment to avoid deterioration. It is unclear which therapy should be first used in these patients and whether there are clues to predict for how long therapy should be continued. Rabin et al1 reviewed the data from 70 patients with CIDP who had responded to therapy and compared the clinical, electrophysiological and laboratory data of 36 patients who could suspend therapy without deterioration (treatment withdrawal) with those of 34 patients who needed to continue the therapy to avoid deterioration (treatment dependent).
The authors found that treatment dependence was more frequently associated with response to IVIg, resistance to steroid therapy, a multifocal deficit and a longer delay from the onset of symptoms to effective therapy. In addition, IVIg were more frequently effective than steroids while the latter were more frequently associated with treatment withdrawal. This confirms what observed in a recent randomised controlled trials (RCT) where monthly IVIg for 6 months were more frequently effective (87.5%) than methylprednisolone (47.6%) given for the same period.2 We should, however, consider that in both studies patients who had failed to respond to steroids within 2 months were shifted to the alternative treatment while the PREDICT study3 showed that the median time to improvement was approximately 4 months after pulsed dexamethasone therapy and 9 months after oral steroids.
One of the most interesting aspects of this study was the fact that treatment with steroids was more frequently associated with the possibility to suspend therapy than treatment with IVIg. Two recent RCT studies showed indeed that the suspension of IVIg after 6 months of therapy was followed by clinical deterioration within 6 months in 40% to 50% of the patients.4 ,5 The follow-up of the PREDICT study showed that the median time to relapse after therapy discontinuation ranged from 11 months for oral prednisolone to 17.5 months for pulsed dexamethasone.6 We observed a similar discrepancy in our study2 with none of the patients on steroids requiring additional therapy within 6 months of suspension compared to 38% of those treated with IVIg. The yet unpublished data on the extension of this study showed, however, that after a median follow-up of 42 months, approximately 80% of the patients in both groups deteriorated even if the median time to deterioration was 4.5 months in IVIg group and 14 months in the methylprednisolone group. All these data indicate that the possibility to suspend therapy is strictly connected with the therapy used.
The authors showed that other factors were significantly associated with treatment withdrawal including an acute or subacute onset, even if the difference was not significant in a multivariate analysis, a symmetrical versus multifocal impairment and a shorter delay from the onset of the disease and the start of an effective therapy. Whether this difference is a predictive factor for treatment withdrawal or for a different response to IVIg or steroid, that influence on their own treatment withdrawal, remains, however, unclear. The same group showed for instance that a multifocal impairment was more frequently associated with a better response to IVIg than to steroids7 which may explain the more frequent treatment dependency in these patients.7 ,8
To summarise, the conclusions of this study should be taken with some caution considering that, given its retrospective nature, it is difficult to clarify whether treatment dependence is related to the clinical features of the patients or whether these influence their response to IVIg or steroids which affect on their own treatment dependence.
Competing interests None.
Provenance and peer review Commissioned; internally peer reviewed.
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