PCR RNA & DNA NAAT Tests

I would just like to know why the PCR RNA test isn't considered a conclusive test according to the FDA? I've read about many different window periods, some as early as 3 days, and others as early as 14 days. They seem pretty reliable from what I've read, the only problems that seem to be in the way is the cost, and the "high" false positive chances, as high as 2.5%. Which isn't a concern for someone who has gotten a negative because the false negative is even lower than a false positive, I'm guessing under the 1% range, so about a 99% percent accuracy. Which isn't much difference from a Gold Standard ELISA test post 3 months, which is around 99.7%.

Are there any statistically significant numbers that point that a negative PCR test turns into a positive ELISA post 3 months?

Sorry for asking so many questions, but it's just interesting to me why an RNA PCR test isn't considered on the same level of reliability as an ELISA.

They don't seem to have a significant difference in accuracy for one to be FDA approved and the other not to be. PCR tests have been used for a while now, and it just seems odd to me why they aren't considered reliable enough for diagnostic purposes.

I think a much shorter window period would save alot of people of that worry for the 3 month period. The expense is definitely a concern, but for those who have access to this test, it doesn't seem like a 3 month ELISA test is necessary unless for anything than re assurance.

hi sir i am male from india, i had sexual high risk exposure with sex worker and she was hiv positive  after i did pcr proviral dna pcr test after 50 days the result was non reactive then after 6 weeks rapid test  for hiv1/2 (SD bioline 3.0) the result was negative then after 3 months elisa result was non reactive then after 5 months elisa result was negative then after 6 months  4th generation elisa test the result was also non reactivethen after 8 months westernblot test that was also negative, then after 8 months rna pcr viral load test for hiv 1 the result was <20 means not detected  but sir my cd4 cell is 453 and cd8 177 and cd4/cd8 ratio high 2.34, then after 9 months tested by two rapid tests kits result was negative ,now i did 3rd generation hiv rapid test after 10 months the result is negative then after 10,11 and now 12 months sd bioline3.0 rapid test all were negative and now after 13 months i did duo test from dr lal path lab the result is negative now after 15 months i have diagnose with  jaundice my hcv and hbv antibodies tests negative after 15 months  i have some ques regarding this:

1) is hiv 4th generation test conclusive after 13 months?
2) is any case who takes more than 1 year to show positive result?
3) i have white coated tounge from 15 months and pain on it is this cause by hiv/ hcv/hbv?
4) i have 2 kg weight loss is this due to hiv?
5) why my cd4 and cd8 low and cd4/cd8 ratio high?
6) is hiv 4th generation test detects all sub type?
7) is 13 months long enough for hiv testing or i have to wait more?
 

1. Western Blot->19th day->neg
2. PCR DNA    -> 36th day->neg
3. Tridot(J. Mitra)->92nd day->neg
4. Combo test(p24 antigen,hiv1 ab,hiv2 ab)->98th day->neg

Sir please let me know what i should do now...