The inter-observer reproducibility of Lasegue's sign in patients with low back pain in general practice

Background. The spectrum of low back pain patients in general practice differs significantly from that in an orthopaedic clinic. The most frequent specific cause of low back pain is nerve-root irritation or compression caused by intervertebral protrusion, and the diagnosis is still problematic. Testing for Lasegue's sign could be a useful way of detecting high-risk patients, but so far the reproducibility of the test has been measured only in hospital-based studies. Aim. To assess the inter-observer reproducibility of Lasegue's sign in general practice. Method. Fifteen General practitioners from Amsterdam and the surrounding areas tested all consecutive low back pain patients who visited them during a period of two years for Lasegue's sign. The test was repeated within two weeks in two samples: sample I consisted of 50 consecutive low back pain patients; sample II consisted of all patients who had pelvic tilt, scoliosis, or positive Lasegue's sign. Results. In sample I, the observation was repeated in 49 patients. The Kappa coefficient was 0.33, and the proportions of positive and negative agreement were 33% and 96%, respectively. In sample II, the observation was repeated in 48 patients. The Kappa coefficient was 0.56, whereas the proportion of positive agreement was 67% and the proportion of negative agreement was 91%. Conclusions. The reproducibility of Lasegue's sign in routine general practice seems to be low, but may be similar to the reproducibility observed in hospital settings in selected patients who have a high chance of low back pain owing to a specific disease.