The Central Sensitization Inventory validated and adapted for a Brazilian population: psychometric properties and its relationship with brain-derived neurotrophic factor

Wolnei Caumo,1–4 Luciana C Antunes,1 Jéssica Lorenzzi Elkfury,1 Evelyn G Herbstrith,5 Raquel Busanello Sipmann,6 Andressa Souza,7 Iraci LS Torres,1,8 Vinicius Souza dos Santos,1 Randy Neblett9 1Postgraduate Program in Medical Sciences, School of Medicine, 2Pain and Palliative Care Service, Hospital de Clínicas de Porto Alegre, 3Laboratory of Pain and Neuromodulation, 4Surgery Department, School of Medicine, Universidade Federal do Rio Grande do Sul, Porto Alegre, 5School of Psychology, Pontifícia Universidade Católica do Rio Grande do Sul, 6School of Medicine, Universidade Federal do Rio Grande do Sul, 7Postgraduate Program in Health and Human Development, La Salle University Center, Canoas, 8Pharmacology Department, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; 9PRIDE Research Foundation, Dallas, TX, USA Objectives: The primary aim was to assess the psychometric properties (including internal consistency, construct validity, reproducibility, and factor structure) of the Central Sensitization Inventory (CSI), adapted and validated for a Brazilian population (CSI-BP). Additionally, we evaluated the relationship between the CSI-BP and the serum brain-derived neurotrophic factor (BDNF) and determined if the symptoms elicited by the CSI-BP discriminate between subjects who do/do not respond to the conditioned pain modulation (CPM) task, as assessed by change in numeric pain scale (0–10) score. Patients and methods: A cross-sectional study was conducted in a pain clinic in a tertiary teaching hospital. A total of 222 adults with chronic musculoskeletal pain and 63 healthy control subjects completed the CSI-BP and the Brazilian Portuguese pain-catastrophizing scale (BP-PCS). A team of experts translated the CSI according to the international guidelines. Test–retest, item analysis, convergent validity, and factor analysis were performed. Later, a random subsample (n=77) was used to correlate the CSI-BP adjusted index with change in numeric pain-scale score during the CPM task and a BDNF blood sample. Results: The CSI-BP presented strong psychometric properties (test–retest reliability 0.91, Cronbach’s a=0.91). Confirmatory factor analysis yielded a four-factor structure, supporting the original English version. The CSI-BP adjusted index showed moderate positive correlation with the BP-PCS, and classified more than 80% of patients correctly vs healthy controls. Serum BDNF levels explained 27% of the variation in the CSI-BP adjusted index. Subjects with impairment in the descending modulatory system had higher CSI-BP adjusted index scores than subjects who responded normally to the CPM task: 49.35 (12.1) vs 39.5 (12.33), respectively (P