Age, reduced renal function, immunocompromised status, prior procedures, and procedure type were found to represent independent predictors of risk of developing a cardiac implantable electronic device infection, and were used to create an infection risk score, according to a study published in the Journal of the American College of Cardiology.
Data for the study were obtained from the Prevention of Arrhythmia Device Infection Trial (PADIT; Clinicaltrials.gov identifier: NCT01002911), a large crossover study in which the effectiveness of conventional antibiotic treatment vs incremental prophylactic antibiotic treatment in reducing infections in patients after the implantation of a cardiac electronic device was assessed.
The study’s primary outcome of the PADIT trial was occurrence of an infection within 12 months of device implantation. Data on patient demographics and characteristics, procedure and device characteristics, and treatment center characteristics were used to develop a risk assessment score for device infection.
Of the 19,559 patients who had a device implanted and completed the follow-up appointment, 0.9% experienced an infection that required hospitalization. Infections were more common in younger patients, men, and those who had experienced heart failure, had compromised renal function, or were immunocompromised. Age, procedure type, renal insufficiency, immunocompromised status, and number of previous procedures were found to be independent predictors of device infection in multivariate analyses.
Based on these variable, an infection risk score was created to generate a model that could be used in the clinical setting to assess the risk for infection. Points were assigned to each variable and summed to calculate a patient’s risk score, on a 0 to 15-point scale. Patients were categorized as being at low- (0-4 points), intermediate- (5-6 points), or high risk (≥7 points), based on their score.
A total of 0.51%, 1.42%, and 3.41% of patients from the PADIT study were found to be at low-, intermediate-, and high risk categories of developing infections, respectively. The risk score and prediction models were internally validated using a bootstrap method.
Bootstrap method for internal validation indicated adequate agreement and discrimination, and subgroup analyses indicated no significant difference in treatment effect for the 2 antibiotic regimens.
Study limitations include a possible exclusion of predictors, the limited follow-up of patients (1 year postimplantation), and the need for external validation of the PADIT infection risk score.
“This study identified 5 independent predictors of device infection and developed a novel infection risk score in the largest cardiac implantable electronic device trial to date, warranting validation in an independent cohort,” concluded the study authors.
Birnie DH, Wang J, Alings M, et al. Risk factors for infections involving cardiac implanted electronic devices. J Am Coll Cardiol. 2019;74(23):2845-2854.