RT Journal
A1 WISWELL TE
T1 ISchemic injury and necrotizing tracheobronchitis
JF American Journal of Diseases of Children
JO American Journal of Diseases of Children
YR 1989
FD November 1
VO 143
IS 11
SP 1259
OP 1260
DO 10.1001/archpedi.1989.02150230017005
UL http://dx.doi.org/10.1001/archpedi.1989.02150230017005
AB Sir.—The article by Hanson et all in the October 1988 issue of AJDC somewhat supported a personal belief that ischemic injury is involved in the propagation of necrotizing tracheobronchitis (NTB). However, I do not believe that their data justify a causal relationship, as the title of the article would imply. Although 58 infants with NTB had either profound hypotension or low 5-minute Apgar scores (the "ischemia" factors that differentiated them from the controls), the remaining 64 affected infants (54%) had neither of these factors. Furthermore, the authors state that their data were analyzed with "a two-tailed t test."1 I suspect that they actually meant that X2 analysis was used. Simplistically, the t distribution is a method of com= paring two group means, while the X2 statistic compares rates or frequencies of discrete findings. The P values presented in the tables are actually those that one would