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Treatment for intestinal helminth infection

BMJ 2000; 321 doi: https://doi.org/10.1136/bmj.321.7270.1224/b (Published 11 November 2000) Cite this as: BMJ 2000;321:1224

Contrary to authors' comments, meta-analysis supports global helminth control initiatives

  1. E Michael, senior research fellow (edwin.michael@ceid.ox.ac.uk)
  1. Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, Oxford OX1 3FY
  2. University of Houston, Houston, TX 77204-5882, USA
  3. Human Development Network, World Bank, Washington, DC, USA
  4. Clinical Trial Service Unit, University of Oxford, Oxford OX3 9DU
  5. Newham General Hospital, London E13 8SL
  6. Control, Prevention and Eradication, World Health Organization, 1211 Geneva 27, Switzerland
  7. Ivo de Carneri Foundation, 10122 Torino, Italy
  8. Epidemiology Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30341-3724, USA
  9. Ivo de Carneri Public Health Laboratory, PO Box 3773, Chake-Chake, Pemba Island, Zanzibar, United Republic of Tanzania
  10. World Health Organization Collaborating Centre for Soil-transmitted Helminthiases, University of Glasgow, Institute of Biomedical and Life Sciences, Glasgow G12 8QQ
  11. Division of Drug Management and Policies, World Health Organization, 1211 Geneva 27, Switzerland
  12. Pan American Health Organization, 525, 23rd Street, N W, Washington, DC, 20037, USA
  13. McGill University, Division of Clinical Epidemiology, Montreal General Hospital, Montreal, Quebec H3G 1A4, Canada
  14. Child Development Programme, University of Natal, Durban 4041, Natal, South Africa
  15. Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT
  16. WHO Representative's Office, PO Box 52, Hanoi, Vietnam 1000
  17. Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, 207 Rui Jin Er Lu, Shanghai 200025, People's Republic of China
  18. Liverpool School of Tropical Medicine, Liverpool L3 5QA
  19. University of Liverpool, Liverpool L69 3GB
  20. King George Medical College, Lucknow, India

    EDITOR—Dickson et al's meta-analysis of the effects of treatment for intestinal helminth infection on growth and cognitive performance in children has produced two important findings, only one of which has been discussed by the authors.1

    The meta-analysis has helped highlight the poor quality of many of the trials carried out so far. The more important result (not remarked on) is the extraordinary finding that, despite the many systematic differences observed between the studies used in the meta-analysis, treatment unfailingly has a positive average effect on both the outcomes studied (table 3). In addition, the fact that many systematic differences were observed between the studies in the meta-analysis seriously questions the value of trying to derive global summary results for any of the comparisons on both statistical and biological grounds.

    The result of the meta-analysis supports an important principle for judging causality from the results of clinical trials—that if different trials address related questions then differences are more likely to occur in the size of any effects than in their direction. When interpreted in this light it is clear that the present results provide quite firm support for the conclusions of the better designed individual trials that anthelmintic treatment may indeed significantly improve child growth and cognitive function; this is in direct contrast to the authors' own pessimistic conclusion. Thus rather than undermining the global helminth control initiatives promoted by the World Bank and World Health Organization, the present review has actually produced evidence in their support.

    References

    1. 1.↵
      1. Dickson R,
      2. Awasthi S,
      3. Williamson P,
      4. Demellweek C,
      5. Garner P
      . Effects of treatment for intestinal helminth infection on growth and cognitive performance in children: systematic review of randomised trials. BMJ 2000;320:1697–1701. (24 June.)
      OpenUrlAbstract/FREE Full Text

    Conclusions should have been based on broader considerations

    1. Alok Bhargava, professor of economics (bhargava@uh.edu)
    1. Wellcome Trust Centre for the Epidemiology of Infectious Disease, Department of Zoology, University of Oxford, Oxford OX1 3FY
    2. University of Houston, Houston, TX 77204-5882, USA
    3. Human Development Network, World Bank, Washington, DC, USA
    4. Clinical Trial Service Unit, University of Oxford, Oxford OX3 9DU
    5. Newham General Hospital, London E13 8SL
    6. Control, Prevention and Eradication, World Health Organization, 1211 Geneva 27, Switzerland
    7. Ivo de Carneri Foundation, 10122 Torino, Italy
    8. Epidemiology Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30341-3724, USA
    9. Ivo de Carneri Public Health Laboratory, PO Box 3773, Chake-Chake, Pemba Island, Zanzibar, United Republic of Tanzania
    10. World Health Organization Collaborating Centre for Soil-transmitted Helminthiases, University of Glasgow, Institute of Biomedical and Life Sciences, Glasgow G12 8QQ
    11. Division of Drug Management and Policies, World Health Organization, 1211 Geneva 27, Switzerland
    12. Pan American Health Organization, 525, 23rd Street, N W, Washington, DC, 20037, USA
    13. McGill University, Division of Clinical Epidemiology, Montreal General Hospital, Montreal, Quebec H3G 1A4, Canada
    14. Child Development Programme, University of Natal, Durban 4041, Natal, South Africa
    15. Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT
    16. WHO Representative's Office, PO Box 52, Hanoi, Vietnam 1000
    17. Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, 207 Rui Jin Er Lu, Shanghai 200025, People's Republic of China
    18. Liverpool School of Tropical Medicine, Liverpool L3 5QA
    19. University of Liverpool, Liverpool L69 3GB
    20. King George Medical College, Lucknow, India

      EDITOR—In their systematic review on the effects of treatment for intestinal helminth infections on growth and cognitive performance in children, Dickson et al note numerous shortcomings in the design of previous studies.1 The authors themselves, however, conclude misleadingly that developing countries should not invest in mass treatment of children against helminth infections. …

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