It
seems not
Oxford University Press (OUP), Science Daily
A new paper published online in the International Journal of
Epidemiology says that
randomized controlled trials (the gold standard method of evaluation) show that
few currently available screening tests for major diseases where death is a
common outcome have documented reductions in disease-specific mortality.
Screening for disease has long been a key component of modern
healthcare. However, several popular screening tests have met with controversy,
with breast cancer screening for women aged 40-49 and prostate cancer screening
in healthy men losing their endorsement in the United States.
Researchers from the Stanford School of Medicine evaluated
evidence on 39 screening tests for 19 major diseases from 48 randomized
controlled trials (RCTs) and 9 meta-analyses identified via the Cochrane
Database of Systematic Reviews, and PubMed -- to find out whether screening
asymptomatic adults for major disease led to a decrease in disease-specific and
all-cause mortality.
Randomized trials were available only for 19 tests on 11
diseases (abdominal aortic aneurysm, breast cancer, cervical cancer, colorectal
cancer, hepatocellular cancer, lung cancer, oral cancer, ovarian cancer,
prostate cancer, type 2 diabetes, and cardiovascular disease).
The authors'
show that there is evidence of a reduction in mortality in only 30% of the
disease-specific mortality estimates and 11% of the all-cause mortality
estimates from the randomised controlled trials they evaluated.
In the case of
disease-specific mortality, findings from the individual randomised controlled
trials are backed up by evidence from 4 meta-analyses, but none of the 6
meta-analyses that included estimates of all-cause mortality produced evidence
of a reduction in mortality.
Professor John Ioannidis, senior author on the paper, says:
"Our comprehensive overview shows that documented reductions in
disease-specific mortality in randomized trials of screening for major diseases
are uncommon. Reductions in all-cause mortality are even more uncommon. This
overview offers researchers, policy-makers, and health care providers a
synthesis of RCT evidence on the potential benefits of screening and we hope
that it is timely in the wake of recent controversies."
The researchers argue that randomised evidence should be
considered on a case-by-case basis, depending on the disease, adding that
screening is likely to be effective and justifiable for a variety of other
clinical outcomes besides mortality. "However," they conclude,
"our overview suggests that expectations of major benefits in terms of
reductions in mortality from screening need to be cautiously tempered."
The International
Journal of Epidemiology also
publishes three commentaries on this paper online today. Peter Gøtzsche of the
Nordic Cochrane Center in Copenhagen argues that although screening is popular
and has "great public and political appeal," we must "demand
much stronger evidence" that it is effective. Paul Shekelle of UCLA, makes
the point that too much screening has been allowed to get into routine practice
without adequate evaluation.
However, he also points out that mortality is not
the only outcome and patients may value screening tests that decrease the risk
of serious morbidity. Paul Taylor of UCL is more circumspect in his commentary,
stating that "the cautious tempering of expectations advised by Saquib,
Saquib, and Ioannidis is prudent but shouldn't be overdone."
Story
Source:
The above story is based on materials provided by Oxford University Press (OUP).Note:
Materials may be edited for content and length.
Journal
Reference:
Nazmus Saquib, Juliann Saquib, and John Ioannidis. Does screening for disease
save lives in asymptomatic adults? Systematic review of meta-analyses and
randomized trials. International
Journal of Epidemiology, 2015 DOI:10.1093/ije/dyu140
Cite
This Page:
Oxford University Press (OUP). "Does screening asymptomatic
adults for major disease save lives? It seems not." Science Daily,
14 January 2015. <www.sciencedaily.com/releases/2015/01/150114205631.htm>.