BMJ : British medical journal
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European height and weight growth charts commonly extend from the 3rd to the 97th centile, whereas in North America the extremes are usually the 5th and 95th centiles. There is no good reason for the difference, and neither chart is particularly useful for screening owing to the high false positive rate associated with a cut off based on the lowest centile. The World Health Organisation's international growth reference uses cut offs based on standard deviation scores rather than centiles, which are more suitable for the extremes of growth status seen in the developing world. ⋯ Here a unified growth chart is proposed: it has nine rather than seven centiles, and they are spaced two thirds of a standard deviation score apart rather than the more usual unit spacing. This gives a set of curves very like the conventional 3rd to 97th centiles, but with additional curves at 2.67 standard deviation below and above the mean (roughly the 0.4th and 99.6th centiles). The 0.4th centile is a more practical cut off for screening purposes than the 3rd or 5th centile.
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To describe the natural course of recent acute low back pain in terms of both morbidity (pain, disability) and absenteeism from work and to evaluate the prognostic factors for these outcomes. ⋯ The recovery rate from acute low back pain was much higher than reported in other studies. Those studies, however, did not investigate groups of patients enrolled shortly after the onset of symptoms and often mixed acute low back pain patients with patients with exacerbations of chronic pain or sciatica. Several sociodemographic and clinical factors were of prognostic value in acute low back pain. Factors which influenced the outcome in terms of episode recovery (mainly physical severity factors) were only partly predictive of absenteeism from work. Time off work and return to work depended more on sociodemographic and job related influences.