Clinical examination variables discriminate among treatment-based classification groups: a study of construct validity in patients with acute low back pain.

BACKGROUND AND
PURPOSE: Treatment-based classification (TBC) provides matched interventions for patients with acute low back pain (LBP) through key history and clinical findings. This study investigated the discriminant validity of TBC by determining whether commonly used clinical examination variables discriminated among TBC groups.
SUBJECTS: The mean age of the 131 participants was 37.7 years (SD=10.1), 66 participants (50.4%) were female, mean duration of LBP was 16.5 days (SD=16.1), and 60 participants (45.8%) had a prior history of LBP. Fifty-one study participants (38.9%) were classified for specific exercise, 42 (32.1%) for mobilization, 28 (21.4%) for immobilization, and 10 (7.6%) for traction.
METHODS: One-way analyses of variance and Kruskal-Wallis tests were used to investigate differences in clinical variables by TBC group. Then, discriminant function analysis (DFA) predicted TBC group membership.
RESULTS: The TBC groups differed on present pain intensity, duration of LBP, and history of LBP. Present pain intensity, duration of LBP, total lumbar flexion, presence of leg pain, and history of LBP produced 2 statistically significant discriminant functions that predicted TBC group membership. These functions correctly classified (cross-validation value in parentheses) 65% (65%) for specific exercise, 45% (40%) for mobilization, and 32% (32%) for immobilization. DISCUSSION AND
CONCLUSION: This study provided evidence supporting the discriminant validity of TBC. Additional diagnostic information related to TBC groups was generated.