INTEREST IN CD2, a global patient-centred study of long-term cervical dystonia treatment with botulinum toxin

Background Longitudinal cohort studies provide important information about the clinical effectiveness of an intervention in the routine clinical setting, and are an opportunity to understand how a population presents for treatment and is managed. Methods INTEREST IN CD2 (NCT01753349) is a prospective, international, 3-year, longitudinal, observational study following the course of adult idiopathic cervical dystonia (CD) treated with botulinum neurotoxin type A (BoNT-A). The primary objective is to document long-term patient satisfaction with BoNT-A treatment. Here we report baseline data. Results This analysis includes 1036 subjects (67.4% of subjects were female; mean age was 54.7 years old; mean TWSTRS Total score was 31.7). BoNT-A injections were usually given in line with BoNT-A prescribing information. The most commonly injected muscles were splenius capitis (87.3%), sternocleidomastoid (82.6%), trapezius (64.3%), levator scapulae (40.9%) and semispinalis capitis (26.9%); 35.5% of subjects were injected using a guidance technique. Most subjects (87.8%) had been previously treated with BoNT-A (median interval between last pre-study injection and study baseline was 4 months); of these 84.8% reported satisfaction with BoNT-A treatment at peak effect during their previous treatment cycle and 51.5% remained satisfied at the end of the treatment. Analyses by geographical region revealed heterogeneity in the clinical characteristics and BoNT-A injection practice of CD subjects presenting for routine treatment. Conclusions These baseline analyses provide sizeable data regarding the epidemiology and clinical presentation of CD, and demonstrate an international heterogeneity of clinical practice. Future longitudinal analyses of the full 3-year study will explore how these factors impact treatment satisfaction.