There’s a joke about evidence-based medicine that critics like to recite:
Since we’ve never had a randomized clinical trial demonstrating that parachutes save lives when people jump out of planes, evidence-based medicine says we shouldn’t recommend parachutes to skydivers.
“That’s an absurd extreme,” says Karina Davidson, PhD, director of the Center for Behavioral Cardiovascular Health in the Department of Medicine. “But what the critics are saying is that some medical practices are so self-evident they should be adopted.”
There’s no doubt that depression is associated with increased cardiovascular risk, but whether it is causal or modifiable is still unknown.
For the authors of an American Heart Association advisory that recommends that cardiologists screen for depression in their heart attack patients, screening is like a parachute.
Though the advisory’s authors acknowledged the lack of direct evidence to support screening, the advisory was issued in 2008 based on hundreds of studies that show that heart attack survivors who suffer from depression are two to three times more likely to have a second heart attack or to die prematurely than depression-free survivors. Roughly 700,000 Americans each year have a heart attack, with 1 in 5 developing signs of depression soon after.
But as critics like Davidson point out, many seemingly obvious screening practices—such as PSA testing for prostate cancer or mammograms for breast cancer detection in women under 50—have been shown to be misguided only in light of recently conducted trials.
That’s why she’s now putting the depression screening advisory to the test, in a 5-year, multi-center randomized clinical trial set to begin later this year.
“People say we’re withholding a cheap and easy benefit to patients if we don’t screen—I ask questions such as how cheap and how beneficial? Nobody really knows, because surprisingly, no trial has been done on heart attack patients and depression screening,” says Davidson, who has been studying the link between mental and cardiovascular health for decades. “Ours will be the first trial to randomize to screening or no screening, which is the critical comparison to be made.”
The trial will soon enroll 1500 patients at three health systems in Oregon, Minnesota, and North Carolina. Patients’ depressive symptoms will be measured after randomization to screening or no screening, along with quality of life and the costs associated with screening.
“We’re trying to answer the clinical question, should we be recommending universal depression screening to cardiologists,” she says. “If it doesn’t help patients in any way, and particularly if it adds cost to the system, then the answer is probably no.”
Biggest Controversy in the Field Will Remain
Regardless of the outcome of Davidson’s trial, the biggest controversy in the field will remain: Will treatment of depression in heart attack survivors improve both their mental and cardiovascular health?
Should we be recommending universal depression screening to cardiologists? If it doesn’t help, then the answer is probably no.
Some small trials have shown that treatment improves depressive symptoms, Davidson says, but no study has found that treating depression in these patients reduces heart attack recurrence or death.
“It’s tantalizing to think depression treatment could reduce cardiovascular disease and death,” Davidson says. “There’s no doubt that depression is associated with increased cardiovascular risk, but whether it is causal or modifiable is still unknown.”
Only a large clinical trial—with 7,000 to 10,000 participants—would be able to determine if depression treatment reduces cardiovascular disease and death. But until then, researchers will continue to argue.
“It’s clear we need a large, fully powered trial,” she says. “That’s the one thing that everyone in the field agrees on.”
The depression screening trial is funded by grant from the National Heart, Lung, and Blood Institute (R01Hl114924).