Infection rates in patients with polymyalgia rheumatica or giant cell arteritis (GCA) are strongly associated with daily and cumulative doses of oral glucocorticoids.

A large study of almost 40,000 adult patients in the UK has found all types of infection were higher during periods of steroid use than periods of non-use.

Most patients (82%) had a diagnosis of polymyalgia rheumatica, 11.3% had GCA and 6.8% had both. The mean patient age was 73 years.

Infection rates increased from 12.9% during periods with no steroid use, to 18.0% for doses up to 4.9 mg/day, and to 35.8% for greater than 25 mg/day.

“For every increase of 5 mg daily dose and of 1000 mg cumulative dose in the last year, the increased risks of all-cause infection were 13% and 50%, respectively,” the study authors reported in CMAJ.

The highest rates were seen for bacterial infections (HR 1.70) and the lowest for fungal infections (HR 1.48).

More than a quarter (26.7%) of patients with an infection required hospitalisation with 7.3% dying within seven days or 8.7% within 30 days.

Deaths were mostly due to pneumonia (52.6%), urinary tract infection (3%) and peritonitis (2.2%).

The study authors said the high excess infection risk and high mortality, even for daily steroid doses of less than 5mg, emphasised the need for regular medication review.

“Patients and clinicians should be educated about the risk of infection, need for symptom identification, prompt treatment, timely vaccination and documentation of history of chronic infection (e.g., herpes zoster),” they said.

“The estimates of dose response can be used to conduct benefit–harm evaluations and cost-effectiveness studies of new glucocorticoid-sparing drugs required to guide policy and improve patient care outcomes in patients with polymyalgia rheumatica or giant cell arteritis,” they concluded.