A simple and quick assessment tool for risk of serious infection in rheumatoid arthritis could help with clinical decision making around medications, prophylaxis or patient monitoring.

A Melbourne study, published in the European Journal of Rheumatology, found 13% of 263 patients in a dedicated RA clinic experienced a serious infection requiring hospitalisation between January 2018 and July 2019.

Respiratory infections, especially community-acquired pneumonia and infective exacerbations of COPD, and UTIs were the most common serious infections.

The median length of hospital stay was four days, most received antimicrobial therapy (88%), and two patients died from severe respiratory infections.

A comparison of RA patients who experienced serious infections and those who did not revealed the predictive potential of low lymphocyte count (OR 4.08), severe infection in the past three years (OR 3.58), Charlson comorbidity index (excluding age) >2 (OR 2.69), and higher DAS28 (OR 1.35).

“An algorithm incorporating these factors and age had a high predictive ability with an AUROC of 0.82,” the study said.

“These findings indicate the potential for routinely available clinical data to be used as a screening tool to identify patients at high risk of severe infection.”

The authors, from Monash University, said in their study that other prediction tools such as the German RABBIT risk score required more extensive data which limit its usefulness in routine practice.

Senior investigator on the Australian study Professor Michelle Leech told the limbic that most clinicians have easy access to the relevant information required to assess infection risk.

“Most clinicians will have a recent white cell count for example. Most clinicians will have some idea of how active the RA is on that day.”

And it was easy to add a quick question such as ‘Have you been in hospital with an infection in the last year’.

Professor Leech said the study team were surprised at how many patients had been in hospital with a serious infection requiring IV antibiotics in the previous year.

“That was a bit of a shock to me and I think we have quite high surveillance in this tertiary clinic. So I have started to be more vigilant about asking patients if they have been in hospital recently because they don’t always come into your own hospital and you don’t always know.”

“It doesn’t take very long to ask that pretty simple question but it turns out we obviously weren’t asking it.”

She said good clinicians probably consider all this information and are thinking about infection risk although they might not do it formally.

However infection risk assessment could perhaps be built in more systematically into an annual or biannual visit.

“I don’t think it’s practical for busy clinicians to think about everything every time. You would really run out of time if you think about bones, infection, drugs, understanding steroids, understanding disease activity, and cardiovascular risk….it’s quite a lot to do and quite a lot to explain to the patients.”

Professor Leech, Deputy Dean of Medicine, Nursing and Health Sciences at Monash, said minimising infection was a fine balancing act in patients with RA.

“… high disease activity itself increases the risk of infection because the immune system is busy looking the other way and fighting a war against itself. Those people need to increase their drugs. In others, they are getting infections because their immune system is suppressed …their medications might be a bit too high.”

“Every person is a bit different,” she said. “Every single patient needs to be weighed up separately. Treatment is not one size fits all unfortunately.”

The study team said their model needs to be validated in independent cohorts.