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Letters

Wrong biochemistry results

BMJ 2002; 324 doi: https://doi.org/10.1136/bmj.324.7334.422/a (Published 16 February 2002) Cite this as: BMJ 2002;324:422

Companies and Medical Devices Agency must act to prevent wrong results

  1. Ian D Watson (ian.watson{at}aht.nwest.nhs.uk), consultant biochemist,
  2. K Lawton, principal biochemist
  1. University Hospital Aintree, Liverpool L9 7AL
  2. Sahlgren Academy at Göteborg University, Sahlgren University Hospital, SE-413 45 Gothenburg, Sweden
  3. Sahlgren Academy at Göteborg University, Sahlgren University Hospital/Mölndal, SE-431 80 Mölndal, Sweden
  4. Clinical Chemistry Laboratory, Västerås Hospital, SE-721 89 Västerås, Sweden
  5. Department of Clinical Chemistry, Lund University Hospital, SE-221 85 Lund, Sweden
  6. Department of Clinical Chemistry and Pharmacology, Centre for Laboratory Medicine, University Hospital, SE-751 85 Uppsala, Sweden
  7. EQUALIS AB, Box 977, SE-751 09 Uppsala, Sweden
  8. Department of Laboratory Medicine, University Hospital of Padua, 35128 Padua, Italy
  9. Department of Laboratory Medicine, Università Vita-Salute San Raffaele, 20132 Milan, Italy

    EDITOR—In their editorial Ismail and Barth discuss the possibility of getting wrong biochemistry results, particularly when immunoassays are done.1 Laboratories try to detect these problems and provide an accurate, clinically relevant result. But the large number of assays done has resulted in widespread reliance on automation, particularly for hormones, and the “one size fits all” approach inherent in this makes the likelihood of inaccurate results quite high.

    What is needed is fit-for-purpose assays on these automated platforms. We are aware, though, of the problems that this may present: we have experienced difficulty in persuading a company that the female testosterone values that its machine produces are analytically incorrect and may lead to inappropriate clinical action if preceded by an oestradiol assay (table). The fact that we elicited similar findings from other centres through a computer mailbase and added this weight of evidence to ours did not matter to the company or, worryingly, to the Medical Devices Agency.

    Readings showing that female testosterone values may be analytically incorrect if preceded by oestradiol assay

    View this table:

    Until companies recognise that, in a clinical governance setting, no-blame reporting is constructive criticism requiring positive action, then inappropriate interventions will continue to affect patients. More critical oversight of analysis and its clinical implications by the Medical Devices Agency is vital. We need confidence that any problem will be addressed either cooperatively or by effective monitoring.

    References

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    Information on incidents with consequences for health should be collected centrally

    1. Göran Lindstedt, professor of clinical chemistry, department of clinical chemistry and transfusion medicine (goran.lindstedt.gu{at}telia.com),
    2. Ernst Nyström, professor, section of endocrinology, department of medicine,
    3. Rolf Ekman, professor of neurochemistry, Institute of Clinical Neuroscience,
    4. Roseanne Forberg, top grade biochemist,
    5. Anders Isaksson, associate professor,
    6. Mats Stridsberg, associate professor,
    7. Lena Hård, biomedical scientist,
    8. Gunnar Nordin, managing director
    1. University Hospital Aintree, Liverpool L9 7AL
    2. Sahlgren Academy at Göteborg University, Sahlgren University Hospital, SE-413 45 Gothenburg, Sweden
    3. Sahlgren Academy at Göteborg University, Sahlgren University Hospital/Mölndal, SE-431 80 Mölndal, Sweden
    4. Clinical Chemistry Laboratory, Västerås Hospital, SE-721 89 Västerås, Sweden
    5. Department of Clinical Chemistry, Lund University Hospital, SE-221 85 Lund, Sweden
    6. Department of Clinical Chemistry and Pharmacology, Centre for Laboratory Medicine, University Hospital, SE-751 85 Uppsala, Sweden
    7. EQUALIS AB, Box 977, SE-751 09 Uppsala, Sweden
    8. Department of Laboratory Medicine, University Hospital of Padua, 35128 Padua, Italy
    9. Department of Laboratory Medicine, Università Vita-Salute San Raffaele, 20132 Milan, Italy

      EDITOR—Like Ismail and Barth, we expect analytical interference in immunoassays to have a greater impact in the future.1 Paradoxically, the increased degree of automation has led laboratory managers to believe that, once automated, assays no longer need supervision by professionals competent in immunoassay. Yet a vital component of the immunochemical assay is antigen-antibody reactions, which may be influenced by several factors, including patient-specific interference.

      We disagree with the view that quality assurance schemes can do little about this. During the past five years the Swedish quality assurance organisation EQUALIS (external quality assurance in laboratory medicine in Sweden) has distributed serum samples suspected of containing interferents, such as heterophilic antibodies or antiligand antibodies, as part of its endocrinology survey.

      Participants are presented with a brief history and are asked to provide results from assays judged to be informative, together with an evaluation of their data in relation to the question at hand and suggestions for further investigation. The data obtained indicate whether generally available assay methods are affected by patient-specific interferents and which diagnostic companies are involved; they can also alert participants to the possibility that their results may be compromised by analytical interference.

      This scheme provides a comprehensive laboratory evaluation of problematic samples not necessarily affected by interferents. Practical knowledge regarding the detection and elimination of interferents is also highlighted at annual meetings for participants, which give opportunities for discussing information. The main drawback is the limited number of participating laboratories due to the limited amount of serum that can be obtained from each patient.

      The confusion created by false values may result in missed diagnosis, unnecessary prolongation of the laboratory investigations, or even incorrect treatment. For instance, it was observed soon after the introduction of an automated system for thyroid hormone measurements that total and free triiodothyronine values were much too low in many patients.2 This information, however, was withheld by the company concerned, and evaluation of the results was left to the doctors. Doctors must therefore be informed of the risk of analytical interference in methods used for laboratory evaluation—for example, through journals.3

      Diagnostic kits vary in their sensitivity to analytical interference. The Food and Drug Administration takes action against non-serious diagnostic companies and prohibits sales of unreliable products in the United States.4 In Europe, however, this problem has essentially been ignored. Hopefully, future European Union directives on in vitro diagnostic products will improve the situation. The vigilance procedure implies that information on incidents with consequences for a patient's health should be collected and evaluated centrally.5

      References

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      Interdepartmental cooperation may help avoid errors in medical laboratories

      1. Mario Plebani, head,
      2. Pierangelo Bonini, head
      1. University Hospital Aintree, Liverpool L9 7AL
      2. Sahlgren Academy at Göteborg University, Sahlgren University Hospital, SE-413 45 Gothenburg, Sweden
      3. Sahlgren Academy at Göteborg University, Sahlgren University Hospital/Mölndal, SE-431 80 Mölndal, Sweden
      4. Clinical Chemistry Laboratory, Västerås Hospital, SE-721 89 Västerås, Sweden
      5. Department of Clinical Chemistry, Lund University Hospital, SE-221 85 Lund, Sweden
      6. Department of Clinical Chemistry and Pharmacology, Centre for Laboratory Medicine, University Hospital, SE-751 85 Uppsala, Sweden
      7. EQUALIS AB, Box 977, SE-751 09 Uppsala, Sweden
      8. Department of Laboratory Medicine, University Hospital of Padua, 35128 Padua, Italy
      9. Department of Laboratory Medicine, Università Vita-Salute San Raffaele, 20132 Milan, Italy

        EDITOR—Ismail and Barth in their editorial on laboratory errors update our knowledge on analytical interferences in immunoassays and emphasise the need to alert clinicians to possible, albeit rare, wrong biochemical results.1 Kilpatrick and Holding report that 45% of results for urgent requests from accident and emergency units and 29% of those from admission wards are never accessed through the ward terminal.2 They emphasise the need to control and improve all steps, from requesting tests to interpreting results and using the total testing process to improving efficacy in the decision making process and in the management of patients.

        Although there are numerous studies on errors in medicine, there is a shortage of scientific evidence for documenting the types of laboratory errors and their frequency, and few studies consider the clinical impact of laboratory errors on medical and economic outcomes. However, a large percentage of laboratory problems have been shown to occur in the preanalytical and postanalytical phases, with fewer mistakes occurring during the analytical steps. 3 4 As most of these problems depend on flaws in healthcare systems rather than classic laboratory errors, they should be defined as patient investigation errors.

        Moreover, these errors often affect the management of patients, both directly and indirectly, because they are associated with inappropriate care, leading to negative medical and economic outcomes.3 These problems can be reduced by technological improvements, mainly in information technology. For example, handwritten test requests could be avoided, and bar codes containing numerous data, including patient identification and clinical details, could be used. Tests could also be requested on a single label, and results could be communicated electronically. A large body of evidence shows, however, that important differences in the quality of laboratory testing and in error rates depend on the staff and their training.5

        This underlines the importance of human resources in preventing and correcting laboratory errors. The greatest possible reduction in laboratory errors is likely to depend on interdepartmental cooperation designed to improve the quality of the collection of specimens and dissemination of data. Further studies are therefore required, and every effort should be made to achieve a more satisfactory definition of laboratory errors, which should be classified on the basis of their real or potential effect on patient outcomes. Moreover, remedies should be found to reduce all errors in commission and omission, particularly those that are closely related to risk for patients.

        References

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