but subsequent tests will not be at that
level, and decisions based on them
are likely to be erroneous.
Second, Brown refers to a conun¬
drum by O'Brien: "Suppose a clinical
investigator at MegaClinic conducts a
clinical trial on treatments A, B, and
C in three groups of patients. At the
conclusion of the trial, the data ana¬
lyst might perform three compari¬
vs C. The
sons: A vs B, A vs C, and
well-trained analyst would see that
the
value for each comparison
should be adjusted downward from
the overall =£.05. That is, he/she
would penalize himself/herself for
doing three statistical tests."
The point is that when the analyst,
X, performs the first comparison (A
vs B), there is no difficulty. When the
second comparison, A vs C, is made,
X is using the same group A as in the
first comparison, and it is likely that
be
The extent
dence is unknown, and the value
effectively decreases by an unknown
amount. When X performs the third
comparison, vs C, X is performing
a test that is likely to have depen¬
dence with the first test, which used
group B, and with the second test,
which used group C. Hence, the
value should be adjusted, to an un¬
known extent, downward from the
overall P^.05. The analyst should pe¬
nalize himselfyherself for doing three
statistical tests.
On the other hand, "suppose that
out in Podunk a study was conducted
of just A vs B. Another investigator in
Boondock studied A vs C. A third re¬
searcher in Foozball studied vs C.
They each used, quite appropriately,
P«.05 for evaluating their two sam¬
Why should the in¬
ple results.
has
the most compre¬
who
vestigator
hensive overview of treatments A, B,
and C be punished with an adjust¬
value that is not
ment to the
the
on
separate studies done
imposed
in three less elaborate trials?" The
answer is that, in the three separate
studies, there is presumably no de¬
pendence between the tests per¬
formed and in the single study, there
is likely to be unknown dependence.
If each group referred to in the "co¬
nundrum" consisted of 100 patients,
altogether, 300 patients are in the first
study. In the separate studies, each of
the three comparisons involves 200
patients (ie, 600 patients altogether).
As fewer patients are involved, we
would expect the first investigation to
Neonates:
the two
comparisons
dependent.
.
.
.
mutually
of depen¬
are
disadvantaged in some way com¬
pared with the second.
Analysts should heed Brown's
warning that repeated statistical tests
on the same elements or subjects in¬
troduce an increase in the risk of a
type I error. In the same vein, Dr
David Kleinbaum commented dur¬
ing a course on epidemiology held
last year in Sydney, Australia, that "if
you torture data sufficiently, they
will eventually confess to some¬
thing."
TED BYRT, MED
Clinical Epidemiology
and Biostatistics Unit
Royal Children's Hospital
Flemington Rd
Parkville, Victoria 3052,
Australia
1. Brown GW. P values. AJDC. 1990;
144:493-495.
Clavicular Fractures in
Frequency vs
Significance
Sir.\p=m-\Iwish to thank Drs Joseph and
Rosenfeld1 for their evaluation of the
frequency and presentation of clavicular fractures in newborns. This is
useful information for "frontline" pediatricians like myself, but I would
like to make the following comments.
The fact that the occurrence of newborn clavicular fractures has remained stable in the Western world
during the past 85 years suggests to
me that the New York State Health
Department may be on the wrong
track if it thinks that this is "an indicator of the quality of care."
Also, it seems that clavicular fractures are benign occurrences that virtually always heal well without intervention. The only reason then to
diagnose clavicular fracture would be
to explain irritability with motion or
asymmetric Moro's reflexes. That
suggests to me that, in children without these symptoms, there may be no
reason to make a significant effort to
make this diagnosis.
MICHAEL J. O'HALLORAN, MD
MIDELFORT CLINIC LTD
733 W Clairemont Ave
Eau Claire, WI 54702-1510
1. Joseph PR, Rosenfeld W. Clavicular
fractures in neonates. AJDC. 1990;
144:165-167.
In Reply. \p=m-\DrO'Halloran points out
that the New York State Health Department may be on the wrong
track in using frequency of newborn
clavicle fracture as a guidelinefor
quality of care. By and large, wethe think
he may be correct. In addition,
requirement for reporting newborn
clavicle fractures in New York State
may lead to unnecessary documentation and costs without any effect on
the quality of care.
Dr O'Halloran also points out that
the only reason to diagnose newborn
clavicle fractures would be to explain
irrisymptoms, such as
tability. Another reason to diagnose
newborn clavicle fractures is to prevent embarrassment at the first office
visit when a large callus is felt covering the healthy broken clavicle. Additionally, we would prefer to make
the diagnosis rather than to have the
parent bring the callus to our attention on or before the first visit.
PAUL R. JOSEPH, MD
Warren Rosenfeld, MD
Department of Pediatrics
unexplained
Winthrop-University Hospital
259 First St
Mineola, NY 11501
Clavicular Fractures
in Neonates
Sir.\p=m-\Weread with interest the article
by Joseph and Rosenfeld1 in the Feb-
ruary 1990 issue of AJDC. We have noticed an increased occurrence of clavicular fractures in our institution
during the last 6 months (12 [1.48%] of
812 newborns). We looked at different
variables, including maternal age, parity, infant's weight, maternal diabetes,
length of labor, oxytocin (Pitocin) induction, delivery methods, local anesthesia, episiotomy, delivery time, and
delivering physician (house staff or attending staff) to find the common factor(s) in these infants.
The only common factor for seven
of the affected infants was a shorter
second stage of labor (mean, 11.4
minutes). In contrast to the authors'
observation that only one of the 18
infants showed "classic" physical
findings, we diagnosed fractures in
11 of 12 infants by the palpation of
instability or crepitation over the fracture site. Roentgenography was used
to confirm our clinical diagnosis. In
one case, two of us (G.C. and J.P.)
and an orthopedist felt a subtle crep¬
itation at the distal end of one clavicle;
however, roentgenography failed to
reveal a clear fracture.
We noticed that a small number of
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