[Question #2202] Quick follow up to Question 2103

45 months ago
As a follow up to my prior question, I ended up doing a 4th generation duo test at 23 days that came back negative.

I've been trying to gather some information on the site about the relative reliability of this and had a couple of follow-up questions I would very much like to run by you.

1. I noticed in some responses Dr. Handsfield suggested a 21 week test was 90% reliable but others suggested maybe it was between 95 and 97% reliable. I understand this is not an exact science but I would be very interested to know what the current thinking is at 23 days if you don't mind.

2. I plan to get a follow up at 31 days, but it seems the current consensus is now 6 weeks for conclusive results. If the 31 day test is negative, based on my facts would you recommend a follow up at 6 weeks? 

3. Would the 31 day result, if negative, still be approaching 99% or more reliability even in light of the new research developments giving rise to the 6 week recommendation?

Thank you again.
45 months ago
Apologies but the reference to 21 weeks above should have been to 21 days.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
45 months ago
Welcome back. I'll be answering your quesiton this time. I reviewed your previous discussion with Dr. Hook. My main thought is to reinforce his comment about how low risk an exposure this was. There is no realistic chance you were even exposed to HIV, let alone infected.

1) Correct, this is not an exact science. So let's say the duo test is 90-98% reliable at 23 days. But for a moment, let's assume it is "only" 90% conclusive. That does not mean there is a 10% chance you have HIV? No, nowhere near it.  If we guesstimate the risk you were infected at something like 1 chance in 100,000, then 90% accuracy means the likelihood you have HIV now around 1 in a million. Looked at in this way, perhaps you'll agree that 95% reliability would make it 1 in 2 million. Does that really seem any different? It doesn't to me and shouldn't to you.

2,3) Also correct:  A recent erudite summary of 4th generation test performance suggested 6 weeks as conclusive instead of 4 weeks, as we often cited on this forum. However, the difference is very small:  the 4 week result probably is "only" 98-99% conclusive, instead of 100%. For the reasons just described, for practical purposes you could indeed consider a negative result at 31 days as conclusive. (Following the math above, odds 9,999,999 out of 10 million that you don't have HIV.) It's up to you whether to consider this sufficiently certain that you can skip the 6 week test.

Does that help? Let me know if anything isn't clear.

HHH, MD
---
45 months ago
Thank you, Dr. Handsfield.  That was very clear and helps put things in perspective.

I'm about out of questions, but will go ahead and do a 4 week and probably 6 week test to confirm, though this has given me a great deal of comfort. I know you get a lot of the same questions so I appreciate your and your colleague's patience.

I'll post those two results to compete the cycle of questions if that's okay, but absent anything unexpected, I feel very comfortable with your advice and am grateful for your time.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
45 months ago
Thanks for the thanks. Stay mellow as you await the time(s) for testing. For the reasons discussed above, you definitely can expect negative results.---
44 months ago
Hi Dr. Handsfield,

I just wanted to follow up with results.  

Duo tests at 31 days and again at six weeks were both negative.  

Is it still safe to consider those conclusive?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
44 months ago
The duo test is always 100% conclusive 6 weeks or more after exposure (usually after 28 days). You can safely stop testing.

That concludes this thread. Since it's your second on this topic, please note the forum does not permit repeated questions on the same topic or exposure. This will have to be your last; future new questions about this exposure and HIV testing will be deleted without reply and without refund of the posting fee. This policy is based on compassion, not criticism, and is designed to reduce temptations to keep paying for questions with obvious answers. In addition, continued answers tend to prolong users' anxieties. Finally, such questions have little educational value for other users, one of the forum's main purposes. I trust you will understand.

Best wishes and stay safe.

---