On my most recent routine visit to the doctor, I got some odd questions from the nurse who saw me first that put me on edge. Had I stopped taking my meds? Had I missed many doses? Well, it didn’t take too many of those questions for me to ask a couple of my own: do I have a detectable viral load, and what is it?
The answer to my impertinent question (we usually wait until I am with the doctor before I discuss actual numbers) put me back at ease…mostly. The detectable viral load result I had was 125. The immediate follow-up test will tell us if that was just a blip, at least it will when I call for the results after a three-week wait (just to make sure the lab has sent the results back).
Because not everyone who reads this will necessarily be familiar with the terminology or the concept, I thought it might be a good topic to explore here.
Sensitivity of the test
When it comes to a viral load result, it is important to contextualize it with the degree of sensitivity of the test measuring it. When I was first diagnosed, the tests used in Québec were sensitive to 500 copies of the virus per millilitre. Anything below that number would not show up as a “detectable” number of copies of the virus. That undetectable did not mean zero was always underlined by the way my test results came back to me: undetectable was recorded as “499”, which I always found useful as a reminder that there might still be virus there, flying just under the radar, but that there was no way to know just how far below the radar it might be.
In mid-1999, Québec moved to viral load testing with a sensitivity of 50 copies per millilitre. There was great fanfare about that, and a lot of explanations about how it would not necessarily be possible to compare the 500 test result to the 50 one. My lab result of undetectable came back now as “49”, as you might have guessed. Suddenly and without fanfare in mid-2010, we had another change to a test sensitive to 40 copies per millilitre, with reporting of undetectable as “39”. The 50 to 40 change was apparently not so drastic as to require a teaching moment by the clinic.
Plotting the results
I have demonstrated in the past my geeky propensity to chart my test results in order to appreciate them more simply and to see the trends more clearly. Viral load results are plotted on a logarithmic scale, where each step up the side is ten times the previous step. That really brings out the anomalies, as you will notice from my viral load graph. When you look at it, you can clearly see four of the five blips I have had, the fifth one having been as result of 40 where undetectable was reported as 39, so it is practically imperceptible.
Seen in the context of the whole collection of my test results, my blips don’t seem all that dramatic. Most of all, that is because we have always done an immediate follow-up test that has come back “undetectable” again, allowing me to relax and breathe easily. My first blip caused me no small panic, as I thought this was surely the beginning of resistance to my meds and I would be on the road to more difficult things to take, and eventually to running out of options, declining and dying. Good thing I’m not a drama queen, right?
The second one was actually my biggest one, and in the context of the test sensitive to 50 copies, 1169 seemed like a lot. But it turned out to be an anomaly again, and I was right back to undetectable. 187 seemed like small potatoes — I didn’t really worry about that, getting blasé about my capacity to bounce back and having a lot of confidence in my stellar record of adherence. 40? I couldn’t tell if that was a blip, or someone new in the lab deciding to report undetectable as 40 instead of 39. We actually didn’t even do a follow-up test that time.
And now 125. Confident that it will also be a blip and not the early indicator of treatment failure, but we’ll have that confirmed (or denied!) by the follow-up test I had. I’m not losing sleep over it.
What does it mean?
There are a few things that it might mean when you have a spike or a blip in your viral load. It could well be the beginning of resistance and treatment failure, but you need to be patient enough to see the result in the context of the results around it. If the increase were really large, there would probably be more reason to be alarmed, but the broader range of treatment options today means that recovery and viral control is not necessarily further away than a change in meds.
At low-drama levels, I have always understood this to be either the manifestation of the variations in the actual levels of viral loads, or the imprecision of the measuring and the possibility of occasional lab errors. In the former case, it’s always useful to be reminded that the viral load can vary based on a number of factors, including adherence and other kinds of infections, as it can be a call to vigilance in those things. In the latter case, it is a reminder that our science is not as clear-cut and black-and-white as we might think if we watch as much TV as I do (a lot of raised expectations by the forensic detective shows).
Does it mean that I was more infectious during those times? Yes, slightly, but that bears some putting into context as well. I’m no fan of our Supreme Court’s recent judgement on the issue of the criminalization of non-disclosure of HIV status, but their standard of low viral load permitting nondisclosure with condom use would have covered every one of my blips. The threshold the court defined was 1,500 copies per millilitre, and I never got to that.
So we’ll see what my follow-up test says (I’ll share it with you in the comments). In the meantime, I’m making sure that I don’t miss any doses with renewed vigour for a while.