@@@@ likehood ratio ??? - icu

[ArchivalUser]

a pt. with high psa ratio if the senestivity of the test is 80% and specificity 90% and case control study showed 10% of the the same age group have the cancer ... what is the like hood ratio if having the same condition for this patient ?
a- 47%
b- 35%
c- 17%
d- 67%
e- can't determined
ps... say why and how to calculate it thanks

[ArchivalUser]

Ans 47%

Lets assume sensitivity(80%) means all disease= 80
and specificity (90%)means all well=90
(TP)True +ve=80 (FP)false +ve= 90 sum= 170
(FN)False -ve=20 (TN) True -ve= 810 sum=830
sum=100 sum=900

and we r looking for the PP (+ve predictive value) right?

so pp=Tp/ Tp+FP= 80/170= .47 or 47% correct me if I'm wrong.

GL

[ArchivalUser]

rt answer thanks