Surgical inpatients who receive seasonal flu vaccines have no worse outcomes than those who are not vaccinated, supporting the CDC's recommendation to to vaccinate hospitalized patients to improve overall coverage rates, researchers reported.
When they compared outcomes among close to 43,000 surgical inpatients who were and were not vaccinated during several influenza seasons, the researchers found no difference in the incidence of fever, infection, and emergency department visits in the 7 days after discharge among the two groups.
Action Points
- Note that this analysis of Kaiser Permanente data found that influenza vaccine administration was not associated with adverse outcomes among surgical inpatients.
- Around 80% of those vaccinated received the vaccine on the day of discharge.
Vaccinated patients did, however, have a slightly higher rate of outpatient, nonemergency physician visits.
"This small increased risk should be weighed against the protective benefits of vaccination," , of Kaiser Permanente Southern California in Pasadena, and colleagues, wrote in an report published Monday.
The CDC's Advisory Committee on Immunization Practices (ACIP) recommends that eligible hospitalized patients receive the influenza vaccine during flu season. But vaccination rates among surgical patients remain low, Tartof told Ƶ.
"One concern among surgeons has been that if patients have an adverse reaction (to vaccination) during their inpatient stay for surgery, it could be confused with a post-op complication or that it might complicate post-op care," she said.
For example, vaccine-associated fever or myalgia could be erroneously attributed to an infectious complication of surgery. Moreover, such effects could influence decision-making during recovery and reflect poorly on surgical performance.
But when Tartof conducted a search of the literature, she found almost no evidence to support this concern.
"It's like an urban legend, only it's more of a clinical legend," she said.
The lack of information on flu vaccine outcomes in the surgical setting led to the newly published retrospective cohort study, which included all patients who had inpatient surgery between Sept. 1 and March 31 each year from 2010 to 2013 at 14 hospitals in the Kaiser Permanente Southern California integrated healthcare system.
The analysis identified all influenza vaccinations administered between the first of August and the end of April in the 2010–2011, 2011–2012, and 2012–2013 influenza seasons.
Outcomes included rates of outpatient visits, readmission, emergency department (ED) visits, fever (temperature ≥38°C), and clinical laboratory evaluations for infection (urine culture, complete blood count, blood culture, and wound culture) in the week following hospital discharge.
Most patients (80%) who were vaccinated received their flu shots on the day of discharge.
Out of about 43,000 surgeries included in the analysis, only 6,420 admissions included a record of flu vaccinations, Tartof and colleagues found.
Rate ratios for various adverse outcomes, for vaccinated versus unvaccinated patients, were as follows, none achieving statistical significance:
- Inpatient visits: 1.12, 95% CI 0.96-1.32
- ED visits: 1.07, 95% CI 0.96-1.20
- Post-discharge fever: 1.00, 95% CI 0.76-1.31
- Clinical evaluations for infection: 1.06, 95% CI, 0.99-1.13
There was a higher risk of outpatient visits in vaccinated patients (RR 1.05, 95% CI, 1.00-1.10, P=0.032), which Tartof and colleagues dismissed as "minimal."
Study limitations cited by the researchers included the lack of data distinguishing planned and unplanned readmissions or outpatient visits and the short follow-up time. Also, there could have been unmeasured factors influencing decisions to offer or accept vaccination. And whether the findings can be generalized beyond the integrated Kaiser system and the southern California population it serves is open to question.
"This study was not able to evaluate overall benefits of influenza vaccination in hospitalized patients because we assessed outcomes only in the 7 days after discharge, which is not long enough for the immune system to respond to vaccination," the investigators wrote.
The researchers noted that efforts to improve vaccination rates within their healthcare system led to higher overall inpatient vaccination rates than have been previously reported. These efforts included automatic prompts to electronic health records reminding providers to vaccinate, the appointment of vaccine champions at each center, and immunization quality metrics.
Tartof noted that the day of discharge appears to be an optimal time to vaccinate patients who have had surgery.
"Before surgery patients tend to be fairly nervous, so this may not be the best time to bring it up," she said. "I would think the best time for the patient and surgery would be on the day of discharge."
Disclosures
The research was funded by the Centers for Disease Control and Prevention.
The researchers declared no relevant relationships with industry related to the study.
Primary Source
Annals of Internal Medicine
Tartof SY, et al "Safety of seasonal influenza vaccine in hospitalized surgical patients" Ann Intern Med 2016; DOI: 10.7326/M15-1667.