Conventional wisdom just isn't what it used to be.
The idea that flu shots might not be protective of the elderly has come up before, but we lack good studies proving, one way or the other, how effective vaccinations are for those over 80.
The Revere's of Effect Measure have produced an excellent analysis of this story.
By Crystal Phend, Staff Writer, MedPage Today
Reviewed by Zalman S. Agus, MD; Emeritus Professor at the University of Pennsylvania School of Medicine.
September 25, 2007
WASHINGTON, Sept. 25 -- Influenza vaccination may save many fewer older patients' lives than generally claimed, according to researchers here.
- Explain to interested patients that this review of influenza vaccination does not support a large mortality benefit in older adults.
- Point out that the CDC recommends annual influenza vaccination for all adults age 65 and older.
The reason is that estimates of a 50% or greater reduction in all-cause mortality have emerged from cohort studies fraught with selection bias, asserted a review article in the October issue of The Lancet Infectious Diseases.
But the real effect with flu shots for those 65 and older during December through March could not have been any greater than 5% to 10%, said Lone Simonsen, Ph.D., of George Washington University here, and colleagues. That's the flu-related mortality burden found in studies of excess all-cause mortality.
Aside from these cohort studies, the evidence is too weak to show any mortality benefit in older adults, who account for 90% of influenza deaths each year, Dr. Simonsen and colleagues added.
However, even a partially effective vaccine is better than no vaccine at all, the researchers said.
"While awaiting an improved evidence base for influenza vaccine mortality benefits in elderly people, we suggest that this group should continue to be vaccinated against influenza," they wrote.
What we know, or what we think we know, is constantly changing. This is particularly true in medicine.
When I was a young medic, 30 years ago, every doctor knew that the very first thing you did for someone in cardiac arrest (after initiating CPR) was to give them a bolus of 1 or 2 amps of Sodium Bicarb to reverse acidosis. Even before attempting to cardiovert. Conventional wisdom said that you couldn't cardiovert an acidotic heart.
And so usually 2 amps of bicarb went in as a matter of course. Because everyone knew that was the right thing to do.
Trouble is, even with our cardiac meds and defibrillators and advanced training, we were losing a lot of patients. By the mid-1980's it became apparent that the bolus of bicarb wasn't helping, and in fact, was probably hurting.
By 1986 several scientific studies had demonstrated that rapid provision of effective ventilation and artificial circulation were entirely adequate means of managing the small amount of respiratory- (or metabolic-) acidosis that accompanied common cardiac arrests. Administration of even 1 amp of Bicarb was linked to poor outcomes.
How could we have gotten it so wrong?
Not only was the problem of acidosis in cardiac arrest overblown, we were reducing our patient's chances of recovery by treating it!
Our scientific knowledge is constantly changing. What seemed like a perfectly good idea in 1980 had become obsolete (indeed, regarded even as dangerous) by 1986. No doubt, some of what we believe to be true or prudent today may be disproved or abandoned five or ten years from now.
Like it or not, we make most of our advances through trial and error. Medicine is still very much an art.
Not much solace for those who are on the receiving end of erroneous assumptions, I suppose.
But we are making progress.