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\begin{document}
\title{How often are statistically significant results clinically relevant? Not
often}
\author[1]{Thomas F Heston}%
\affil[1]{Johns Hopkins University}%
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\date{\today}
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\begin{abstract}
\textbf{Objectives:}~Statistical significance does not equal clinical
significance. This study looked at how frequently statistically
significant results in the nuclear medicine literature are clinically
relevant.~\textbf{Methods:}~A medline search was performed with results
limited to clinical trials or randomized controlled trials, published in
one of the major nuclear medicine journals. Articles analyzed were
limited to those reporting continuous variables where a mean (X) and
standard deviation (SD) were reported and determined to be statistically
significant (p \textless{} 0.05). A total of 32 test results were
evaluated. Clinical relevance was determined in a two-step fashion.
First, the crossover point between group 1 (normal) and group 2
(abnormal) was determined. This is the the point at which a variable is
just as likely to fall in the normal distrubution as the abnormal
distribution. Jacobson's test for clinically significant change was
used: crossover point = (SD1 * X2 + SD2 * X1) / (SD1 + SD2). It was then
determined how many SD's from the mean this crossover point fell. For
example, 13.9 +/- 4.5 compared to 9.2 +/- 2.1 was reported as
statistically significant (p \textless{} 0.05). The crossover point is
10.7, which equals 0.71 std from the mean: 13.9 - (0.71*4.5) = 9.2 +
(0.71*2.1).~ ~\textbf{Results:}~The average crossover point was 0.66
SD's from the mean. The crossover point was within 1 SD from the mean in
26/32 cases, and in these cases averaged 0.45 SD. Thus, for 4 out of 5
statistically significant results, when applied to an individual
patient, the cut-off between normal and abnormal was 0.45 SD from the
mean. This results in a third of normal patients falling into an
abnormal category.~\textbf{Conclusions:}~Statistically significant
results frequently are not clinically significant. Statistical
significance alone does not ensure clinical relevance. ~ ~%
\end{abstract}%
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Thomas Heston\textsuperscript{1} and Richard Wahl\textsuperscript{1}
1. Johns Hopkins University, Baltimore, MD.
\emph{This abstract was presented at the 2009 Annual Meeting of the
Society of Nuclear Medicine in Toronto, Canada.}
Citation: Heston T, Wahl R. How often are statistically significant
results clinically relevant? Not often.
\href{http://jnm.snmjournals.org/content/50/supplement_2/1370}{J Nucl
Med~May 2009~vol. 50~no. supplement 2~1370} ~
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