four weeks, 48% after eight weeks, 35% after 12 weeks, and at the end of the follow up year 10% of the patients still had low back pain. The rapidly diminishing slope of the survival curve indicates that the chance of low back pain resolving within the following week is highest during the first weeks after the initial visit, diminishing almost to zero at the end of the follow up year (fig 1 ). In chronic cases, the time to recovery appeared to be longer than in recent onset cases (p&lt;0.05). The median time to recovery in chronic cases was 10 weeks (IQR 5 -- 25), and in recent onset cases the median time was six weeks (IQR 3 -- 14). The severity of the pain until recovery from the index episode At the initial visit the median pain was 25 (IQR 15 -- 34) on the 50 point scale. The median pain, if still having pain, quickly diminished after the initial visit and seemed to stabilise if patients did not recover (table 2 ). The median improvement on the 50 mm scale (paired analysis), in patients whose index episode had not yet ended, was 7 mm during the first four weeks (IQR 12 -- 1), 7 mm during the second period of four weeks (IQR 10-1), 2 mm in the next period of four weeks (IQR improved 5 -- aggravated 1), and 0 mm during the remaining part of the follow up (IQR improved 6 -- aggravated 7). Severity