Data collection

We divided baseline data collection into two stages. The first stage consisted of a structured interview with history taking and questionnaires. The second stage consisted of physical examination. The interview included questions on (i) demographic and patient characteristics, (ii) lifestyle behavior, (iii) symptoms’ characteristics, (iv) psychological factors, and (v) comorbidities. To accommodate for the requirements in text limit a more comprehensive description is provided in Table 1.

Contents of the Brazilian BACE interview.

AUDIT-C, alcohol use disorders identification test; BBQ, Back Beliefs Questionnaire; CES-D, Center for Epidemiologic Studies Depression Scale; FABQ_A, Fear Avoidance Beliefs Questionnaire; FES, Falls Efficacy Scale; NRS, Numeric Rating Scale; PCS, Pain Catastrophization Scale; PSQI, Pittsburg Sleep Quality Index; RMDQ-Br, Roland Morris Disability Questionnaire – Brasil; SCQ, Self-administered Comorbidity Questionnaire; SF 36, Short Form (36) Health Survey.

The physical examination included assessing trunk mobility, measured by finger-to-floor distance test; gait speed measured during a 4.6 m route, then converted to total meters per second (m/s); the Timed Up and Go (TUG) test8 measured in seconds (s); the dominant handgrip strength in kg/F, using a manual handheld dynamometer (SAEHAN Hydraulic Hand Dynamometer, SH5001 – 973, 8 KOREA).