Health related quality of life is improved by botulinum neurotoxin type A in long term treated patients with focal dystonia

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Abstract
OBJECTIVES The advent of botulinum neurotoxin type A (BoNT/A) gave rise to substantial progress in the treatment of focal dystonias. In the light of the high costs of the toxin and the necessity to establish valid outcome indices for this treatment apart from sheer reduction of dystonic muscle tone and posture, the impact of focal dystonia and its treatment with BoNT/A on patients' health related quality of life (HRQL) was determined. METHODS Fifty patients with cranial and cervical dystonia treated long term with BoNT/A were enrolled in a prospective, open labelled cohort study. The HRQL was assessed using the EuroQol (EQ-5D) and the short form 36 health survey questionnaire (SF-36) at baseline before BoNT/A injections and at two follow up visits after 6 and 12 weeks covering one BoNT/A treatment period with maximum effect size at the first follow up. RESULTS Compared with a general population sample, a considerable negative impact of focal dystonia on HRQL was found in patients under investigation. In both disease types, BoNT/A treatment led to a significant improvement in several HRQL dimensions, in particular providing moderate to marked effect sizes in the fields of mental health and pain. The impairment of HRQL due to pain as well as the BoNT/A induced improvement within this SF-36 subscore were significantly higher in patients with cervical dystonia. Under BoNT/A therapy, no correlation was found between changes of clinical outcome scores and HRQL measures. CONCLUSIONS The data confirm that BoNT/A is able to induce a significant, but temporary amelioration of several aspects of HRQL in both types of focal dystonia. This may substantially contribute to the patients' subjective benefit from the therapy. Moreover, the data provide further arguments to accept high costs of the BoNT/A treatment in these severely handicapped patients, as a consequence of its considerable benefit on quality of life.