Obesity influences rheumatoid arthritis diagnostic tests

Obesity causes patients to receive higher scores in blood tests used to diagnose rheumatoid arthritis even if they do not have the condition, researchers have warned.

Obese patients have higher levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), regardless of whether they have rheumatoid arthritis, researchers have found.

The study published in Arthritis Care & Research, said fat mass could push up CRP and ESR levels, which could be mistaken for arthritis disease activity.

Blood tests to determine CRP and ESR levels are used to assess levels of inflammation in the body, which in turn is used to diagnose rheumatoid arthritis or determine how effective treatment is.

Over 2,100 patients with rheumatoid arthritis were involved in the trial, which was compared with data from the general population.

Among women in the general population and those who had rheumatoid arthritis, CRP levels increased in line with BMI, becoming especially high in those with severe obesity, the researchers found. ESR levels also increased, but at a more modest rate.

In men with rheumatoid arthritis, lower BMI was associated with greater CRP and ESR, contrasting positive associations among men in the general population – who followed the same pattern as women.

Clinicians should keep the association in mind when testing patients, the researchers said.

Rheumatoid arthritis

Lead author Dr Michael George said: ‘Our results suggest that obesity may lead to increased levels of CRP and ESR in women with rheumatoid arthritis.

‘The increase in these levels of inflammation was not because rheumatoid arthritis was worse in these women. In fact, we found that obesity leads to very similar increases in these lab tests even in women without rheumatoid arthritis.

‘Physicians might assume that high levels of inflammation mean that a patient has rheumatoid arthritis or that their rheumatoid arthritis requires more treatment when in fact a mild increase in levels of inflammation could be due to obesity instead.’

GPC clinical and prescribing lead Dr Andrew Green said doctors should look at changes over time in CRP and ESR values to diagnose patients and take into account individual differences.

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins

Register

Already registered?

Sign in

Follow Us:

Just published

Death certification during the coronavirus outbreak

Death certification during the coronavirus outbreak

The MDU's Dr Ed Nandasoma answers questions relating to certifying deaths in all...

Coronavirus: Key guidance GPs need to know about COVID-19

Coronavirus: Key guidance GPs need to know about COVID-19

GPonline provides an overview of the key guidance relating to coronavirus, including...

NICE publishes rapid guidance on managing COVID-19 in primary care

NICE publishes rapid guidance on managing COVID-19 in primary care

New guidance on symptom management in patients with suspected and confirmed COVID-19...

GPs fear missing vital COVID-19 advice as data avalanche swamps NHSmail

GPs fear missing vital COVID-19 advice as data avalanche swamps NHSmail

GPs risk missing vital information during the COVID-19 pandemic because a deluge...

GPs can use NHS volunteers service to check on vulnerable patients

GPs can use NHS volunteers service to check on vulnerable patients

GPs can refer vulnerable patients to the NHS volunteer scheme for support with tasks...

Free coronavirus news and resources on GPonline, MIMS and MIMS Learning

Free coronavirus news and resources on GPonline, MIMS and MIMS Learning

As the coronavirus crisis continues, we at Haymarket are constantly seeking new ways...