INTRODUCTION: The Backache-Index (BAI) is applied to patients with low back pain (LBP) in order
to help doctors/surgeons perform physical examinations easily and it is carried out within a short
space of time (< 2 min.) without using inclinometric instruments.
PURPOSE/AIM: To explore reliability, validity and responsiveness of the BAI in patients with LBP,
which can fulfil the existing need for a reliable routine examination in the clinical environment.
MATERIALS & METHODS: In total, 75 patients with subacute LBP participated in a randomized
controlled study (1). The BAI consisted of a scoring system that includes pain factors and stiffness
estimation at the end of a series of five different lumbar movements of a patient standing in erect
RESULTS: The (blinded) inter-observer reliability between 2 observers for the BAI was perfect (ICC =
0.96). A BAI change of one unit is able to exclude a measurement error. A significantly good
correlation (P < 0.001) was found between BAI at baseline, and Oswestry Disability Index (ODI, R =
0.62) and MPQ-PRIT, as the total degree of pain rating index (R = 0.57). The effect size and
discriminative ability were explored after two treatment sessions. The greatest level of distinction was
found for MPQ-PRI-T and BAI (AUC > 0.93), followed by ODI (AUC = 0.92). A less distinction was
found for MPQ-NWC-T and Visual Analogue Scale (VAS, AUC > 0.82).
RELEVANCE: the BAI is available in different languages: English, Spanish, French, Dutch, German,
ITALIAN, Portuguese, Russian, Turkish, Hebrew, Chinese, Japanese and Thais.
CONCLUSIONS: The Backache Index or BAI appears to be a reliable and valid assessment of overall
restricted spinal movements in case of LBP and discriminates between successful and unsuccessful
DISCUSSION: The inter-observer reliability after a few minutes for the BAI was sufficient. The validity
of the BAI was found to be good with the ODI and moderate with the VAS. A Backache Index change
of one unit is able to exclude a measurement error.
KEYWORDS: Low back pain; Outcome scales; Reliability; Validity; Impairment; Pain rating scales.
IMPLICATIONS: In a Spanish study (2) the test-retest after 3 days of the same group (n=46) revailed
that the reliability for the 5 outcome scores was good (ICC=0.73). No significant difference was found
between BAI1 (4.65 ± 4.15 ) and BAI2 (4.72 ± 4.20) and the absolute reliability was perfect with an