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HIV Test and Index Value (SIGNAL-TO-CUT OFF RATIO) (INDEX VALUE)
Dec 17, 2008

I am sending donation for your grate service. I would like to know about Index Value in HIV 1&2 Antibody Test. After six months from the possible exposure I have conducted a HIV 1&2 Antibody & p24 Antigen Compo Test. The Test Result is:- Index Value 0.11 (Non Reactive)

Index Value < 0.90 0.90 -1.00 Borderline Provisionally Reactive, > 1.00 Provisionaly Reactive.

What it meant. I am negetive. What are the posibilities to Postive at this 6 months.

Response from Dr. Frascino

Hello,

Your test result at six months of "0.11" is "nonreactive." That means you are definitively and conclusively HIV negative. The "index value" (also called the "signal-to-cutoff ratio") is a technical term having to do with how this type of HIV-antibody test is conducted. Values less than 0.90, like yours, are definitively negative! Values between 0.9 and 1.0 would be equivocal or borderline. And values above 1.0 would be preliminarily positive. These preliminarily positive (or provisionally reactive) tests require a confirmatory test before someone is told they are HIV positive (infected). However, none of this applies to you, as you are conclusively HIV negative.

I'll post below some questions from the archives that discuss the signal-to-cutoff ratio ("index value").

Happy Holidays. WOO-HOO!

Dr. Bob

I'm sure you haven't been asked this before! (SIGNAL-TO-CUT OFF RATIO) Dec 8, 2008

Dear Honorable Dr. Bobalicious!

I just want to clarify a few things regarding my previous posting in which you told me that you could not determine of my HIV status based on my storyline.

I did some research on your website (the postings) and found 2 postings with your answers that I found to be contradicting each other. Too bad I could not find the other 1 posting, but managed to find the other one. The postings are about Condom Breakage / Condom Left Inside The Vagina.

As for my story, let me make it clear, short and simple for you because its been killing me for the past week or so. I hope you can help me this time around.

- I went to a local massage place in Batam, Indonesia, to entertain a client of mine. When I went inside after choosing a girl in her 20s, she began to undress me and herself. I went into the bathroom to wash my dick. While she also washed her vagina, in which she said, Your dick is clean already. My vagina is clean too. I could see it was trimmed neatly and there was no foul smell whatsoever coming out of her vagina. Here, I thought she was quite careful about cleanliness, so I guessed shes at least care about the cleanliness of her guests personal groin areas, as well as hers, therefore low risk of STDs.

- Then she performed oral sex on me, in which did not touch her teeth at all. I assumed she was a pro and that raised my risk for HIV. I ejaculated some semen before she put on the condom. But then all of a sudden, my dick got all limpy. She then put on the green DUREX condom on my dick (half-limp), then put it inside her vagina (in which she licked with her salive to make it wet first). Then, with just 2-3 thrusts, I came inside her, I could still feel the loose condom on my dick (or not sure), then when I pulled out my dick, I did not see the condom anymore! It stayed inside her vagina, in which she said, Oh.. the condom stuck inside. She then took out the condom and then washed it off, a clear sight that I ejaculated inside the condom. I was damn afraid that during the slight pull-out my dick was exposed to her vagina.

And then, 1 week (7 days) after the exposure of the slipped-condom, I went to a diagnostic lag to get my blood tested for HIV. I got my blood withdrawn, and the test came back Non-Reactive with an index of 0.28 (Its <0.90). I know that this test is not conclusive and I plan to get my blood tested again at the 3 months mark, its just that I could not stand the torture of waiting.

Heres my questions:

1) What is the chance of my risk getting HIV here? 2) What does the index ratio 0.28 means? Does it mean that as the number get bigger, the chance of getting HIV is greater too? I read somewhere that the index ratio number does not mean anything.

I am sure nobody asked you this kind of question with Index Ratio before right? So, please answer me this time, with thorough replies, as it will definitely ease up my worries. Please, I am waiting for your reply.

Where can I send my donation too? Considering I am in Batam. Can I just wire-transfer it?

Worried Sick,

James

Response from Dr. Frascino

Hello James from Batam,

Thanks for clarifying (somewhat) your situation. However, if you are "not sure" if the loose condom was around your limp dick, I certainly have no way of knowing either! Since the condom remained entirely within the love canal, I would suggest you consider your HIV risk the same as unprotected insertive penile-vaginal sex. The estimated statistical risk for acquiring HIV from unprotected insertive penile-vaginal sex with a partner confirmed to be HIV positive is 5 per 10,000 exposures. Your estimated statistical risk would be less, as we do not know the HIV status of your Indonesian masseuse.

As for the signal-to-control-index ratio (also called the signal-to-cut off ratio), what you read is correct. If it's less than the cutoff value (in your case, less than 0.90), then the test is negative. Whether the number is larger or smaller doesn't matter as long as it's less than the cutoff value. Negative is negative! As for nobody asking me these types of questions before, see below! The range and scope of questions I responded to over the years is impressively vast.

Since this confusion surrounding signal-to-cut off ratios comes up fairly frequently let me take a moment to try and explain it once again. The signal-to-cut off ratio varies from laboratory instrument to laboratory instrument and it also varies with each run of the test assay. A cut off value is analogous to a noise signal from the instrument when a blank sample is run. The "signal" is a real signal coming from the anti-bodies that are being tested in the plasma. If the ratio greater than or equal to 1, it means that the anti-body signal is equal to or higher than the threshold value, which also means that there are significant amount of anti-bodies in the sample being tested.

On the other and, a signal-to-cut off ratio is less than 1 (any value less than 1) means that the signal from the anti-bodies is much less than the baseline value (value from a blank run). The test is designed such that when it detects the anti-bodies, the minimum value it records is 1. A true positive test is usually higher than 1. Values close to 1 can indicate infection or more likely a false positive. The bottom line take home message is that if you have HIV anti-bodies in your blood, you will see signal-to-cut off ratio values greater than 1. Values less than 1 indicate HIV antibodies are not present. (It doesn't matter how much less than one 1. A ratio of .22 is not "more negative" than a ratio of .45.

As for making donations to the Robert James Frascino AIDS Foundation from Batam (or anywhere), yes, bank-to-bank wire transfers work well. The wiring instructions are: Mellon Bank Pittsburgh, P.A. ABA # 043000261 Credit ML Account Number 101-1730 Further Credit to: Robert James Frascino AIDS Foundation Account # 830-04C48 For international transfers add: Swift number MELN US 3P Additional information about donations can be found on the foundation's Web site at www.concertedeffort.org. We accept credit cards, PayPal, checks, money orders, cashier's checks, cash, diamond mines, oil fields, alien spacecraft, you name it. Good luck!

Dr. Bob

Irrational fear?? oral rimming hiv please help me Dr Robert! Apr 29, 2008

Dear Doctor Robert. First I really gotta say you are an angel! I admire your patience and dedication to inform us about the facts. You really make a difference in people's lives and I'm sure you have brought so-much-needed peace of mind and night-sleep to thousands of people out there! The world needs more people like you. I live in a very catholic and conservative society and I can't talk about this to anyone and it just makes this experience worst. My parents would never forgive me if they find out what happened. I've read the forums over and over and I somehow started developing this sort of 'friendship' feeling towards you because reading this forum and your answers is the closest I have to actually talking to someone about this. I hadn't plan on writing because some questions are already answered but I really need your help now. I actually was trying to get some rest right now (3.40am) but I just had a panic attack and I really need to 'hear' from you. Your words about if I should worry or not could really make the difference in my life. I can't sleep and I started shaking of fear! My mouth is so dry that it hurts. I'm having even suicidal thoughts and that is just so not like myself!!. Its horrible. I think I'm being irrational and I can't recognize myself. it makes me want to cry. literally.

I had a bi-curious experience about 4 weeks ago. It was with a guy from whom I don't know his hiv status, and we had: - oral sex (both ways) with a latex sensitive condom -deep kissing (and our bodies rubbed to each other, I had a 'healing pimple' in my abdomen but we were still wearing a condom) and I don't think anything other than his skin from his abdomen touched it -and he performed rimming on me. I suspect he might have spitted saliva from his mouth there to 'lubricate'

It was my first and probably last experience with a guy because I realized it wasn't my thing. Everything was fine, I thought I did good for having experimented in a 'safe' way and find out if wetter I was really Bi or not, but with days I started worrying I could have caught an STD. I was really worried that I got hepB or syphilis (because of the rimming)and I started stressing sooooo much. A week ago I woke up with a white coating and red sores. So now my worry was HIV. First I was worried it was thrush or Oral Hairy Leukopia and It was horrible . I felt so bad for what I had done!! I lied to my parents to get out that night and I feel extreme guilt. I went to the ER next day and doctor there wasn't really very 'open-minded' but told me white coating must have been caused for antibiotics I took just the week after the 'exposure' (I was on 2 pills a day clarythromicyn for 10 days for a sinus I had before)and the extreme stress i was going through for the situation. She didn't know exactly what the white coating in the tongue was (I suspect now it can be hairy geographic tongue based on google pics, but its first time in my life that it happens. coincidence?? see i hate my mind for making those questions), so she told me to get an HIV test (blood taken just 3 weeks after the experience), a syphilis and a hepB test

All the hepatitis b, syphilis and HIV elisa test they all came negative. My worries started AGAIN when I saw my hiv test negative (..3 weeks I guess was too soon) but with a Signal to cut-off ratio (S/co) of 0.42. If the number equals to 1 or above, is positive. Below is negative. But the 0.42.. Is that number relevant?? Having seen that number brought fears on me again because after just 3 weeks I would have expected that number to be lower. Now I'm fearing that number at the 3rd week (so soon in the window period) means I'm 40% into being a HIV positive

I'm so worried ever since that I can't sleep. I can't concentrate in my studies and I can't do anything else in the day than thinking about HIV. I have to wake up in 2 hours for uni and still i can't go to sleep thinking about that. I know its not the end of the world if they detect hiv on me, but still it is serious enough to worry me and making me feel so bad. I decided to stop reading about hiv symptoms because that just made my anguish worst

Please tell me if my experience was risky!! Do I have to worry about it? Do you think that if i wouldn't be so worried I would actually need an HIV test? sorry if its a dull (and long!) question but I swear I need your help. I'm feeling so lonely and worried right now. You are my hope to get back to sanity :'(

Please help me!!

Sincerely yours, Me

Response from Dr. Frascino

Hello Me,

Your post is just one of many that I receive on a routine basis from "very" Catholic ("Christian") conservative communities in which the writer emphatically states their parents "would never forgive me if they find out what happened." This unfortunate combination of guilt and fear can, and often does, lead to incredible emotional anguish, anxiety and desperation. Your 3:40 AM panic attack, stemming from your having absolutely no one to even confide in, is lamentable. Even more tragic are your "suicidal thoughts," which are present even though you clearly realize you are being irrational. Correct me if I'm wrong, but having grown up Catholic, it is my understanding the entire religion is based on forgiveness. Christ dying for the sins of all believers, right? That's why I find it so curious that parents like yours would be so "un-Catholic" as to "never forgive" their own son! Perhaps you aren't giving them enough credit. Perhaps they really would understand your predicament if you gave them a chance. However, I do realize many ultra-religious folks would not. How sad it is their un-Christ-like behavior could (and sometimes does) drive their children to commit suicide! Parents like that should have a very nasty surprise waiting for them when they reach the Pearly Gates! OK, back to your problem!

Your HIV-acquisition risk is insertive and receptive oral sex and getting rimmed. Oral sex carries an extremely low risk for HIV transmission. There are no documented cases of HIV transmission from rimming or getting rimmed.

Next, the inevitable "symptoms" (induced by guilt and irrational fear) began appearing. Your HIV test, syphilis screen and hepatitis B test at three weeks were all negative. However, you are now completely freaked out because your signal-to-cut-off ration (s/co) was 0.42. How unfortunate no one explained to you that an s/co ration less than "1" is negative and that the exact ratio below 1 has absolutely no diagnostic significance! The s/co ration has to do with the specific test assay and in my opinion probably shouldn't even be reported out on the lab slip. The only relevant point is the cut-off value, i.e. above one: positive; below one: negative. That your value was 0.42 does not mean you are 40% on the way to being HIV positive!!! No way. No how! (Just like you can't be partially pregnant! You either are or you "ain't"!

My advice is simple:

1. If you are worried, and clearly you are, get a rapid HIV test at the three-month mark. (HIV-antibody tests taken prior to the three-month mark are not considered to be conclusive.)

2. Whether you are straight as a lawn dart or gay as the Christmas windows at Macy's, I suggest you get some psychological counseling to explore sexual orientation issues. "Bi-curious" is often a stop along the way to understanding and accepting your true sexuality, which in turn is crucial to your ultimate long-term health and happiness.

3. Consider doing something to change the constrictive and unhealthy atmosphere fostered by your "very Catholic" environment. Begin talking about HIV/AIDS awareness to your friends and family.

4. Consider getting a more compassionate and competent physician with whom you can discuss any issue or problem. I'd also recommend you get vaccinated for hepatitis A and B.

5. Read through the wealth of information and testimonials on this Web site to increase your basic understanding of sex, safer sex, HIV acquisition/transmission, HIV prevention and HIV diagnostic tests.

Good luck.

Dr. Bob



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