[R] prop.trend.test issue

[Ethan Johnsons]

I have the clinical study data.

		                           Year 0 	Year 3
Retinol (nmol/L) 	N 	Mean +-sd 	Mean +-sd
Vitamin A group 	73 	1.89+-0.36 	2.06+-0.53
Trace group 	           57 	   1.83+-0.31 	  1.78+-0.30

where N is the number of male for the clinical study.

I want to test if the mean serum retinol has increased over 3 years
among subjects in the vitamin A group.

>  1.89+0.36
[1] 2.25
> 1.89-0.36
[1] 1.53
> 2.06+0.53
[1] 2.59
> 2.06-0.53
[1] 1.53


> prop.trend.test(c(2.25, 1.53),c( 2.59, 1.53))

        Chi-squared Test for Trend in Proportions

data:  c(2.25, 1.53) out of c(2.59, 1.53) ,
 using scores: 1 2
X-squared = 0.2189, df = 1, p-value = 0.6399

The issue I am seeing that N of Vitamin A group = 73 seems not reflected.
This leads me to think that I can't implement the test based on the
data just presented.
Nor a two-tailed test is possible.

        2-sample test for equality of proportions with continuity correction

data:  c(2.25, 1.53) out of c(2.59, 1.53)
X-squared = 0, df = 1, p-value = 1
alternative hypothesis: two.sided
95 percent confidence interval:
 -0.6738203  0.4112720
sample estimates:
   prop 1    prop 2
0.8687259 1.0000000

Warning message:
Chi-squared approximation may be incorrect in: prop.test(c(2.25,
1.53), c(2.59, 1.53))

Any ideas, please?

thx

ej