Musculoskeletal corticosteroid injection (CSI) is a frequently used treatment, considered safe with a low incidence of minor side effects.
To investigate whether the incidence of acute coronary syndrome (ACS) is increased following corticosteroid injection for musculoskeletal conditions.
Data were reviewed from 41,276 patients aged over 40 years and hospitalised with ACS between January 2015 and December 2019. Each ACS case was allocated up to 10 control patients from their primary care clinic, matched for age and sex. The cases and controls were reviewed for orthopaedic or rheumatological consultation including a CSI procedure and occurring prior to the hospital admission date. The incidence of CSI was compared between the case and control groups.
Data from a total of 413,063 patients were reviewed, 41,276 ACS cases and 371,787 controls. The mean age was 68.1, standard deviation (SD) = 13.1, 69.4% male. In the week prior to their hospital admission, 118 ACS patients were treated with CSI compared with 495 patients in the control group; odds ratio (OR) = 1.95 (1.56-2.43). In total, 98% of CSI procedures were carried out by orthopaedic specialists. An association between ACS and prior CSI was strongest in the days immediately prior to hospitalisation: OR = 3.11 (2.10-4.61) for patients who were injected 1 day before ACS. The association between ACS and CSI declined with increasing time between injection and hospital admission: at 90 days OR = 1.08 (0.98-1.18). The association remained robust when cardiovascular risk factors, history of rheumatological disease, and other co-morbidity were taken into consideration.
Musculoskeletal corticosteroid injection appears to substantially increase the risk of acute coronary syndrome.

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