SAN FRANCISCO – Researchers have devised a five-item scoring formula to quantify the risk for infection in patients undergoing placement, revision, or removal of a cardiac-rhythm device based on data from nearly 20,000 patients enrolled in a recent infection-prophylaxis trial.
The risk score can help identify patients who might benefit from intensified antibiotic prophylaxis, and it can also help during shared decision making with patients to better understand the risk a patient faces from infection, compared with their predicted device benefit,, said at the annual scientific sessions of the Heart Rhythm Society.
The new risk score produced a concordance statistic, the area under the receiver-operator characteristic curve, of 0.704. It showed that, although it could use further validation, the score as it currently stands has substantial predictive value, said Dr. Birnie, professor of medicine at the University of Ottawa and deputy chief of cardiology at the University of Ottawa Heart Institute. “It’s certainly better than anything we have now,” he said in a video interview.
Dr. Birnie and his associates used data they collected on baseline characteristics and infection outcomes of the 19,603 patients enrolled in(Prevention of Arrhythmia Device Infection Trial) who underwent a rhythm-device procedure at 1 of 28 participating Canadian centers. The primary aim of PADIT was to assess the safety and efficacy of an intensified antibiotic-prophylaxis regimen, compared with a standard regimen of a cefazolin infusion just before the procedure. The study’s primary endpoint was the incidence of hospitalization for device infection during 1-year follow-up, and while the intensified prophylactic regimen linked with a 23% relative reduction in the hospitalization rate, compared with standard treatment, the difference was not statistically significant ( ).
The researchers analyzed the baseline patient data and the blindly adjudicated infection outcomes and identified five factors that were independently associated with an increased infection rate. They organized the five factors and produced a formula they call the PADIT score (see chart). Those five factors are: prior procedures (the greater the number the greater the risk), age (which unexpectedly had an inverse relationship with infection incidence), depressed renal function, immuno-compromised status, and type of procedure. A patient can potentially score 0-15 points.
Among the PADIT patients a score of 0 correlated with about a 0.3% rate of hospitalization for a device-related infection during 1 year of follow-up, a score of 5 with about a 1.1% rate, a score of 6 with about a 1.8% rate, and a score of seven or more with a 3.4% infection rate over the following year. About 5% of patients had a score of 7 or more, and roughly another 5% had a score of 5 or 6, Dr. Birnie said. At his center, clinicians have begun routinely calculating scores for patients scheduled for an arrhythmia-device procedure, and they are considering routinely administering added antibiotic prophylaxis to patients with a preprocedural score of 6 or higher. They may also use the score to determine whether to use the antibacterial envelope recently reported to prevent cardiac-device infections ().
“It’s very easy for patients to get to a PADIT score of 7 or higher,” Dr. Birnie noted. As an example, he cited a common patient, an 85-year-old with renal dysfunction who is under consideration for a second replacement of an implantable cardioverter defibrillator. The patient would score 1 point for renal insufficiency, 2 points for the type of device, and 4 points for having a prior history of two devices, and the consequent 3.4% risk for infection might counterbalance the potential benefit this elderly patient could expect from the new device. The score will be very important for targeting treatment, shared decision making, and selection of patients for future intervention trials, he concluded.
“I think this risk score will change practice by giving clinicians a better idea of a patient’s risk for infection,” commented, professor of medicine at the Mayo Medical School, Rochester, Minn., and director of heart rhythm services at the Mayo Clinic in Jacksonville, Fla. The PADIT score will help identify patients for whom leaving a device in place is a better option than taking it out because of their infection risk. The risk score could also help improve the cost effectiveness of preventive treatments, such as antibiotic-eluting envelopes, by targeting treatment to higher-risk patients, Dr. Kusumoto said during a press briefing.
SOURCE: Birnie DH. Heart Rhythm 2019, .