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GPs 'should stop using inflammatory markers as non-specific test'

GPs should stop using CRP and other inflammatory markers as non-specific tests to rule out serious underlying conditions, researchers have recommended. 

The authors of a study published in the British Journal of General Practice called for a review of NICE guidelines for chronic fatigue and irritable bowel syndrome after finding that only 15% of patients with raised inflammatory markers actually had an underlying pathology.

The researchers from Bristol Medical School calculated that per 1,000 inflammatory marker tests performed, 236 false-positive results could be expected, leading to an additional 710 GP appointments being needed, and 24 referrals.

The study looked at just under 137,000 patients who had had an inflammatory marker test in 2014.

They found that in patients with raised inflammatory markers, only 15% had an underlying condition such as an infection, autoimmune condition or cancer. The remaining 85% were classed as false-positives.

Patients who had false-positive results had around 10 GP appointments in the six months following the test, compared with seven in patients who had true-negative results. The false-positive patients also had around 24 further tests requested, compared with 14 in the true-negatives.

Due to the low sensitivity of inflammatory marker tests, they are ‘not suitable’ for ruling out underlying disease in primary care, the researchers concluded.

They said in the paper: ‘Though the unit cost of inflammatory marker tests is relatively low, the total costs, including follow-on consultations, investigations, and referrals, are likely to be substantial. As well as financial costs, patient anxiety and GP workload may be generated. Further studies, including health economic evaluations, may be useful to inform clinical guidelines and recommendations for GPs about when (and when not) to use inflammatory marker tests.’

Dr Jessica Watson, a GP and lead author of the study, said: ‘We recommend that GPs stop using inflammatory markers as a non-specific test to rule out serious underlying disease. We would also like to see a review of NICE guidelines for chronic fatigue and irritable bowel syndrome, which currently promote the use of inflammatory markers to exclude other diagnoses.’

NHS England announced plans in 2018 to require point-of-care CRP testing in primary care before GPs could prescribe antibiotics, in a bid to curb antibiotic prescribing. 

Readers' comments (26)

  • I hope the courts reflect on this advice when we are dues for not following NICE guidance,
    I notice as a GP trainer, my st3 doctors nearly always order a crp for all patients and the partners rarely do so.....
    Until the courts realise the implications on the nhs by ordering so many tests nothing will change as we all adopt extreme defensive medical practice.....”just in case....”

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  • Defensive practice first in this 'Spanish inquisition' type treatment of the medical profession.No one expects the Spanish inquisition,well at the moment we do.So as far as I am concerned defensive practice continues bu**er the cost to the NHS if we are finished off by the combined might of the regulator and the parasitic legal maggots feeding on the rapidly fading medical profession its not the researcher career on the line it is ours.Pandoras box of defesive medicine has been wide open for a while and no amount of ivory tower thinking will close it now.(Sorry showing my age with the Monty Python reference)Rant over!

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  • Fine to miss 15/100 cancers, infections etc then as long as we refer to twr clinic on a 3% threshold!
    ;-)

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  • Does any practising GPseriously think that missing 15% of serious underlying illness will be regarded as acceptable by patients, their relatives, the GMC, the Courts, or anyone outside academia? Bonkers, bonkers, bonkers.

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  • I very rarely use inflammatory markers to rule out serious pathology. Thanks to this study I will start using them regularly.

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  • I’m horrified. That’s a non-disposable tourniquet in the picture. I hope someone has filled in an incident form.

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  • 15% yield is better than most screening tests.... sorry Dr Watson... not following your lead on this one...... the prosecution will always be able to find an expert who will argue you should have ordered a CRP......Im going to keep ordering CRP where I feel its warranted and for vague illness. I take it this is another portfolio GP?

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  • Dear All,
    How raised? WHat was their threshold for a raised crp, anything out of range or the age related calculation? And how many of the follow up tests were repeats of the crp to see what it was doing?
    We all have patients who've lived happily for years with raised ESRs.
    Regards
    Paul C

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  • It’s published in the RCGP journal. That’s how much weight I will give this study. ‘Nuff said.

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  • CRP missing an "a"

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