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A stranger to the lavatory


Laxatives are big business. Over 11 million GP prescriptions were dispensed in England in 1996, apart from over-the-counter sales. Many people have a real or imagined problem with their bowels. So when two linked systematic reviews recently landed on Bandolier's desk they were eagerly grasped for some answers. Alas - all is not as clear as it might be.

The first [1] review of 36 trials was precised in Bandolier 46 . The authors chose mean bowel movement frequency per week. Overall findings showed that laxatives and fibre consistently increased bowel movements compared with placebo (an extra 1.5 bowel movements per week) although there was no conclusion as to the relative merits of laxative or fibre. One of the possible criticisms was that most of the studies were conducted in populations in which the control groups had more than 3 bowel movements a week when one definition of constipation is fewer than three movements a week.

A second review from the Health Technology Assessment stable [2] starts with the epidemiology of constipation (which is really interesting) and definitions of constipation, followed by methods of clinical management. The search was based on the Tramonte article, widened to include a number of other databases and also non-English language papers. It evaluated treatment in the elderly and excluded papers for participants under the age of 55. Without information that elderly patients respond differently, this may not have much logic. The meta-analysis doesn't add a lot, and there are a few errors, which is a pity. In direct comparison treatments, a comparison of magnesium hydroxide versus laxamucil reports laxamucil as more effective but the text reports magnesium hydroxide as being more effective than laxamucil.

Where does this leave things? There is evidence that laxatives and fibre increase bowel movements but we still do not know how well they work. In spite of the paucity of evidence some £45M of laxatives are dispensed in England every year. Money down the drain ?

References:

  1. SM Tramonte, MB Brand, CD Mulrow, et al. The Treatment of Chronic Constipation in Adults - A systematic review. Journal General Internal Medicine, 1997 12: 15-24.
  2. M Petticrew, I Watt, T Sheldon. Systematic review of the effectiveness of laxatives in the elderly. Health Technology Assessment 1997 1: No 13.



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