Letters

Validation of a rapid whole blood test for diagnosing Helicobacter pylori infection

BMJ 1997; 314 doi: http://dx.doi.org/10.1136/bmj.314.7095.1688a (Published 07 June 1997) Cite this as: BMJ 1997;314:1688

Conflicting results from the Helisal test

  1. Anne Duggan, Research fellowa,
  2. Richard Logan, Reader in clinical epidemiologya
  1. a Department of Public Health and Epidemiology, University Hospital, Nottingham NG7 2UH
  2. b Gastrointestinal Research Unit, Leicester General Hospital, Leicester LE5 4PW
  3. c Department of General Practice, Medical School, University of Birmingham, Birmingham B15 2TT
  4. d Down Lisburn Health and Social Services Trust, Lagan Valley Hospital, Lisburn, County Antrim
  5. e Department of Public Health and Primary Care, Radcliffe Infirmary, University of Oxford, Oxford OX2 6HE
  6. f Oxfordshire Health Authority, Headington, Oxford OX3 7LG
  7. g Bishop Auckland Hospitals NHS Trust, Bishop Auckland General Hospital, Bishop Auckland, County Durham DL14 6AD
  8. h Centre for Digestive Diseases, General Infirmary at Leeds, Leeds LS1 3EX

    Editor—P Moayyedi and colleagues are not correct in stating that the accuracy of the Helisal test for diagnosing Helicobacter pylori had not been independently evaluated before their report.1 As shown in the table, several groups have now reported their findings. The results show a variation in the accuracy of the test that was not revealed by Moayyedi and colleagues' results.

    Why are their results rather better than those of others? They do not mention any problems in interpreting the tests, although two groups found 5-10% of tests difficult to read (Stone et al; Lahaie et al (table 1); we also found a similar difficulty. In one study there was disagreement between two observers in 6% of cases (Stone et al (table 1). Another important point omitted by Moayyedi and colleagues was the type of blinding used to ensure that the tests were read independently. Were the Helisal tests read before or after the endoscopy?

    View this table:
    Table 1

    Accuracy of Helisal test for diagnosing H pylori infection in six studies

    We are puzzled as to why the authors emphasise the number of endoscopies avoided using a test intended primarily for use in primary care. Whereas screening for H pylori in patients already referred to hospital may prove cost effective, the existing evidence suggests that screening for H pylori in primary care and then referring positive cases for endoscopy is not a cost effective strategy.3 It would be even less so if the Helisal test performs as poorly as others have found.

    References

    1. 1.
    2. 2.
    3. 3.

    Assessment lacked certain considerations

    1. R J Robinson, Research fellowb,
    2. M A Stone, Research fellowb,
    3. J F Mayberry, Consultant physicianb
    1. a Department of Public Health and Epidemiology, University Hospital, Nottingham NG7 2UH
    2. b Gastrointestinal Research Unit, Leicester General Hospital, Leicester LE5 4PW
    3. c Department of General Practice, Medical School, University of Birmingham, Birmingham B15 2TT
    4. d Down Lisburn Health and Social Services Trust, Lagan Valley Hospital, Lisburn, County Antrim
    5. e Department of Public Health and Primary Care, Radcliffe Infirmary, University of Oxford, Oxford OX2 6HE
    6. f Oxfordshire Health Authority, Headington, Oxford OX3 7LG
    7. g Bishop Auckland Hospitals NHS Trust, Bishop Auckland General Hospital, Bishop Auckland, County Durham DL14 6AD
    8. h Centre for Digestive Diseases, General Infirmary at Leeds, Leeds LS1 3EX

      Editor—In presenting the results of their validation of the Helisal rapid blood test for diagnosing Helicobacter pylori infection, P Moayyedi and colleagues rightly emphasise that the test needs evaluating in the area in which it is to be used.1 The high sensitivity and specificity found in their study are not …

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