Statins and Influenza
By Amesh A. Adalja, MD, FACP, January 6, 2012
Because infection with influenza virus is associated with myriad inflammatory changes that determine severity of disease, pharmaceutical modulation of inflammation has been a goal of treatment of influenza. Researchers have been particularly interested in the cholesterol-lowering statins for this purpose. The Journal of Infectious Diseases recently published results of a multistate retrospective analysis of the effect of statins on 30-day mortality of laboratory-confirmed influenza. This study, conducted by Vandermeer and colleagues,1 provides new evidence of the benefits of statins in treating influenza.
Analysis of EIP Surveillance Data
Data on statin use in hospitalized influenza patients was collected from the U.S. Centers for Disease Control and Prevention’s (CDC) Emerging Infections Program’s (EIP) influenza hospitalization surveillance system in effect in 59 counties in 10 states—which covers 7% of the U.S. population. The time period studied was October 1, 2007, through April 30, 2008. Subjects were adults admitted with influenza that was laboratory confirmed with either viral culture, immunofluorescence antibody staining, PCR, a rapid antigen detection test, or serologic testing.1
7% of the U.S. Population
The EIP surveillance system yielded 3,043 eligible subjects with the following demographics:
Median age of subjects: 70.4 years
Of those with known vaccination status, 57.1% were vaccinated against influenza
One-third received statins prior to or during hospitalization for influenza
Of those on statins, 76% were on statins prior to hospitalization (and had them continued during hospitalization)
11% had statins initiated during hospitalization
Compared with those not taking statins, subjects on statins were older, had a greater number of comorbid conditions, and were more likely to have received influenza vaccination, all of which were statistically significant differences. The use of antivirals within 48 hours of admission was not different between the two groups―approximately 25% in each group took antivirals.1
Less Mortality in Statin Group
Overall, 5% of the study population died within 30 days of an influenza diagnosis. Using unadjusted data, no benefit was found for statin users. However, when a model that adjusted for collinearities and other variables was employed, statin use was found to decrease the odds of mortality by 41%. By comparison, in this model, antiviral treatment within 48 hours and receipt of vaccine were not shown to influence 30-day mortality rates. Subgroup analysis of those who initiated statin therapy upon hospitalization (111 patients) was not possible due to small sample size; however, when the analysis was restricted to only those who were taking statins prior to hospitalization (ie, excluding the 111 who began statin therapy during hospitalization) a similar mortality benefit persisted.1
Do Statins Have a Role in Management of Influenza?
This study, which, importantly, was restricted to subjects with laboratory confirmed influenza, adds to the mounting retrospective evidence that statin use may be beneficial for those with influenza. However, several important questions remain to be answered:
Is statin use simply a marker for healthier patients? This question is raised in an accompanying editorial.2
Would statin use be protective if prompt antiviral treatment was initiated?
While it is probably ill advised to stop statin therapy during hospitalization for influenza, is there a benefit to initiating statin therapy upon hospitalization solely for influenza infection?
Are certain strains of influenza more susceptible to statin therapy (eg, H3 vs. H1)?
These and other questions can be best answered by a randomized controlled trial in patients naïve to statin use.
Vandermeer M, Thomas AR, Kamimoto L, et al. Association between use of statins and mortality among patients hospitalized with laboratory-confirmed influenza virus infections: a multi-state study. J Infect Dis 2012; 205:13-19.
Walsh EE. Statins and influenza: can we move forward? J Infect Dis 2012; 205:1-3.
Previous CBN posts related to this topic:
Immunomodulation in 2009 H1N1. Amesh A. Adalja, MD, February 18, 2011
An Alternative Approach to Pandemic Influenza that Clinicians Everywhere Could Use.Guest Editorial by David S. Fedson, MD, July 23, 2010
Cytokines and H5N1: Still No Clear Answers. Eric Toner, MD, July 30, 2007
Could Statins Improve the Outcome of Influenza? Luciana Borio, MD and John G. Bartlett, MD, September 29, 2005