Measurement properties of the Brazilian-Portuguese version of the PROMIS-29 questionnaire and the Impact Score in patients with chronic low back pain

Background A task force from the US National Institute of Health aimed to establish parameters for surveys with patients with chronic low back pain (LBP) by recommending the use of the Patient-Reported Outcome Measurement Information System 29-item (PROMIS-29) questionnaire and the stratification according to the Impact Score. We aimed to assess the internal consistency, reliability, measurement error, construct validity and responsiveness of the Brazilian-Portuguese version of the PROMIS-29 questionnaire (version 2.1) and the Impact Score in patients with chronic LBP. Methods A prospective cohort study was carried out with patients with chronic LBP who were receiving physiotherapy treatment in clinics in S & atilde;o Paulo and Vit & oacute;ria cities, Brazil. The sample included 102 patients with chronic LBP, aged between 18 and 80 years, and with the ability to read and write in the Brazilian-Portuguese language. Exclusion criteria were patients with serious spinal conditions, cognitive impairment, pregnant women, and patients who had undergone lumbar surgery within the past six months. The PROMIS-29 questionnaire, the 12-item Short-Form Health Survey and the Roland-Morris Disability Questionnaire were applied. The PROMIS-29 questionnaire was reapplied after 24 hours and 4 weeks. Results The PROMIS-29 questionnaire showed Cronbach's Alpha values between 0.81 (anxiety) and 0.91 (depression). The ICC2.1 ranged from 0.85 (95% CI: 0.77 to 0.89) to 0,97 (CI 95%: 0.95 to 0.98). The SEM values ranged between 0.85 (physical function) and 2.62 (ability to participate in social roles and activities). The Impact Score showed Cronbach's Alpha, ICC2.1 and SEM values of 0.91, 0.97 (95% CI: 0.95 to 0.98) and 0.56, respectively. The PROMIS-29 questionnaire and the Impact Score showed sufficient construct validity. The PROMIS-29 questionnaire showed moderate responsiveness, while the Impact Score showed sufficient responsiveness. Conclusions Both the Brazilian-Portuguese version of the PROMIS-29 questionnaire and the Impact Score showed sufficient internal consistency, reliability, construct validity and responsiveness in Brazilian patients with chronic LBP. The results support the US National Institutes of Health's recommendation to use the PROMIS-29 questionnaire and the Impact Score in patients with chronic LBP. We suggest that future studies evaluate the structural validity of the Brazilian-Portuguese version of the PROMIS-29 questionnaire.