Screening for mannose binding protein gene in routine practice is unnecessaryBMJ 1997; 315 doi: https://doi.org/10.1136/bmj.315.7105.428 (Published 16 August 1997) Cite this as: BMJ 1997;315:428
- Catherine Hawke, Senior registrar in public health medicinea
Editor—John A Summerfield and colleagues suggest that mutations in the mannose binding protein gene are associated with infections in children attending their hospital paediatric department.1 They also conclude that screening for such mutations should be included in the investigation of severe or frequent infections, but they fail to explain why. What is the point of screening? How can identifying such mutations in these children improve outcome? They mention no effective interventions for patients carrying the gene.
The number of new tests introduced into routine laboratory practice has increased steadily,2 and there is no authority responsible for evaluating them. The research and development programme aims to identify priorities for research, and many innovations are being evaluated; an unknown quantity, however, are creeping into practice. To get some idea of the scale of diffusion of new biochemical tests into practice I surveyed three centres in the Anglia and Oxford region. I found that, of new tests introduced in the past five years, only just over half were known to improve clinical outcomes or to be more sensitive and specific than their predecessors. Hospital specialists were the group most influential at getting the new tests into routine practice.
The introduction of new tests often seems to be due to the enthusiasm of individuals rather than to systematic evaluation to prove appropriateness, effectiveness, and good value for money matched with corresponding clinical knowledge and a corresponding research base. The cost of the tests is often low and hidden from commissioners of health care within clinical contracts. The burden falls on other budgets as patients with false positive results are inappropriately investigated and treated.
Screening for the mannose binding protein gene as part of a controlled study to identify the risk conferred or as part of other research is acceptable. We should not, however, rush into recommending that yet another test is introduced into routine practice when there is no evidence to suggest that it will do more good than harm.