Objective: To assess the test-retest reliability of a questionnaire to determine nonspecific low back pain (NLBP) and its characteristics in schoolchildren aged 7 to 12 years.
Methodology: An evaluation of diagnostic technologies was done in 84 schoolchildren (9.2 ± 1.6 years), 50 % girls, selected for convenience. The questionnaire was administered by individual interview, twice, with an interval of 2 to 4 days. We calculated the Intraclass Correlation Coefficient (CCI 2.1) to quantitative variables and Cohen’s and Weighted Kappa Index to qualitative variables with their respective confidence intervals at 95 % (CI95 %).
Results: The prevalence was 20.2 % and 17.9 % in the first and second evaluations, respectively. The reliability of the questions that determine the prevalence of NLBP was very good (k = 0.85, 95 % CI 0.69 – 1.00, n = 84); The number of days with NLBP in the last month got fair reliability (CCI = 0.36; 95 % CI -0.009-0.70), while the duration asked by four categories of response was very good (k = 1.00; IC95 % 1.00-1.00), the intensity assessed by Wong-Baker Faces Pain Rating Scale was very good (ICC = 0.82, 95 % CI 0.54 – 0.93). In relation to consulting a professional for back pain, Kappa indices ranged from k = 0.46 and k = 1.0. In the second evaluation, the children showed a shorter duration of pain (3.9 days) and lower intensity (2.0).
Discussion: The importance of reliability evaluation of the questionnaire to determine DLI and its characteristics is that there can be a valid measure unless the measure has some degree of reliability. The questionnaire to determine NLBP and their characteristics in schoolchildren aged 7 to 12 years are sufficiently reproducible for use in population studies.
Key words: Low back pain, questionnaires, reliability, child, pain measurement.