False Positive COVID Tests; Cannabis and Car Accidents

TTHealthWatch is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media for Johns Hopkins Medicine, and Rick Lange, MD, president of the Texas Tech University Health Sciences Center in El Paso, look at the top medical stories of the week.

This week’s topics include false-positive COVID tests, COVID in kids and diabetes risk, cannabis and car accidents in Canada, and two diabetes drugs for weight loss.

Program notes:

0:51 COVID in kids and diabetes development

1:53 Did increase in some more than 100%

2:50 An immune response?

3:23 False positives in antigen tests for COVID

4:23 Abbott antigen test device

5:25 Number of positive in almost a million

6:20 Cannabis among those who’ve had car accidents

7:21 Drivers treated in trauma centers

8:22 Put some teeth into reducing

8:45 Semaglutide and liraglutide in overweight adults without diabetes

9:50 Followed 68 weeks

10:35 Semaglutide appears better

11:30 Prevention first

12:18 End

Transcript:

Elizabeth Tracey: False positive tests with rapid antigen tests for COVID.

Rick Lange, MD: Are kids with COVID infection at a higher risk of developing diabetes?

Elizabeth: Can diabetes drugs be used to help people lose weight even when they don’t have diabetes?

Rick: And marijuana legalization and its detection in injured automobile drivers.

Elizabeth: That’s what we’re talking about this week on TT HealthWatch, your weekly look at the medical headlines from Texas Tech University Health Sciences Center in El Paso. I’m Elizabeth Tracey, a Baltimore-based medical journalist.

Rick: And I’m Rick Lange, president of Texas Tech University Health Sciences Center in El Paso where I’m also dean of the Paul L. Foster School of Medicine.

Elizabeth: Rick, for both of us, gosh, COVID, continuing apace in rapid increases in hospitalizations in both our necks of the woods. Why don’t we turn first to MMWR? We are seeing this rather disturbing increase in hospitalizations and certainly infections among children. What about this relationship with the development of diabetes?

Rick: It appears that in adults that COVID infection may put them at an increased risk of diabetes. These investigators sought to ask the question, “Gosh, in kids less than 18 years of age who have COVID infection, does it increase the risk of diabetes shortly thereafter?”

They looked at kids that had been infected and they compared them to both kids pre-pandemic — they also had kids during the pandemic, but didn’t have COVID infection. Then they also some that had an acute respiratory infection, but it wasn’t COVID at all. Then they followed them over the course of time and said, “OK, we know what the incidence of diabetes was pre-pandemic, during the pandemic in kids that didn’t have infection, and those with acute respiratory infection. Is it higher in individuals that had COVID infection?”

What they found was that’s exactly the case. Depending on which population they looked at, it increased the risk anywhere from 31% to 166%. It could be either type 1 or type 2. It even increased at 116% compared to kids that had had a non-COVID respiratory tract infection. It’s not just having a respiratory tract infection that does it, it actually is being COVID-infected.

There is the misperception that kids do fine if they get COVID, but this goes to the fact that they could have either long-term symptoms, they could develop an inflammatory response a month later, and now we know that they could also have an increased risk of diabetes after COVID infection.

Elizabeth: I think the thing I’m wondering about is whether this resolves over time and I don’t think we know the answer to that one yet. I mean, we certainly see especially type 2 diabetes go away in adults, for example, after they have bariatric surgery or even significant weight loss by other means.

Rick: That’s a good point. This study didn’t address that. In fact, it didn’t address whether it was type 1 or type 2 diabetes. Type 1 diabetes does not go away. We don’t really know why the risk of diabetes goes up. It could be that the virus is directly attacking pancreatic cells, or it could be an immune response doing that. Or these are maybe kids that have pre-diabetes and it just tips them over into diabetes. The next step would be validating it, saying, “Is it long standing?” Then, third is what’s the mechanism behind it.

Elizabeth: Right. I would note on a positive, though, aspect of SARS-CoV-2 infection in kids right now that, at least with the Omicron variant, it appears that MIS-C is occurring less often in kids than it was before. It was already rare, but it seems like it’s occurring less often.

Rick: And that MIS-C is that multi-inflammatory system complex.

Elizabeth: Let’s turn to JAMA. This is a research letter that’s taking a look at something that right now is front and center. Gosh, I don’t know about you, but I have been hearing about all these people out there buying all these rapid antigen tests that they can use at home to see whether or not they have got COVID, and the prices have skyrocketed. There are all these ones out there that aren’t even real.

This raises the issue of, well, how often do these rapid antigen tests give a false positive result? This is clearly really important right now for, I would suggest, people who work in health care. Because even though the CDC is saying, “Now you need to isolate for 5 days rather than 10,” we are still experiencing these acute health care worker shortages because they’re infected.

This is a study that was done in Canada. They were looking at asymptomatic employees who were screened twice weekly from January 11 of last year to October 13^th. They were provided with this Abbott Panbio COVID-19 antigen rapid test device. They looked at these false positive results among these people. They administered almost a million of these things over 537 workplaces — and they only gleaned 1,322 positive results among those folks — and then they confirmed the positives with PCR.

Ultimately, this turned out to be the number of false positive results, 0.05% of these screens. The vast majority of those occurred — 60% — in two workplaces and were the result of this particular device, a lot of this particular device that I have already identified.

The authors conclude that these results demonstrate that you really need to have a comprehensive data system — we know we are not going to get that, so let’s not even think about that right now — and then just being aware if you get a cluster, if you will, of those kinds of positive tests and see if this might be a possibility.

Rick: Elizabeth, as you noted, the number of positive tests in the almost a million tests they performed were positive. That is 0.15%. Then they took those positive tests and they immediately did PCR. If the PCR was negative, they concluded correctly so that the antigen test was falsely positive. That happened in about 40% of the positive tests. Then when they drilled down a little bit further, they realize that that was due to just two batches of this particular rapid test device. But without a comprehensive data system, there is no way to determine that. I thought this was fascinating because I never even thought that false positives occurred very often.

Elizabeth: Right. If you’re getting that kind of a cluster, maybe it is something to follow up and take a look at the device itself.

Rick: Right, and you can determine if it’s false positive by either getting a second test from a different type of device or subjecting a sample for PCR evaluation.

Elizabeth: Since we’re talking about Canada, let’s turn to the New England Journal of Medicine, this rather disturbing study, I thought, taking a look at rates of cannabis positivity among those who have had car accidents.

Rick: Yeah. So cannabis is the second most commonly used recreational drug worldwide — alcohol being number one. Everybody is aware that its legal status is changing. Recreational cannabis use is legal in South Africa, in Uruguay, in 17 U.S. states, two U.S. territories, and the District of Columbia. Recreational use became available in Canada in 2018.

Canada actually tried to establish guidelines to limit drivers that could be potentially impaired with cannabis. What they did was they set legal limits just like they did for alcohol, they expanded the police’s ability or power to collect evidence of having drug-impaired driving — so everybody that gets injured in an accident gets tested — and then they have also included criminal charges if someone’s levels are too high.

They said, “OK.” They studied drivers treated after a motor vehicle collision in 4 different British Columbia trauma centers from 2013 to 2020, before legalization and afterwards, and asked a simple question, “How often did people have any detectable cannabis?” Then, “Did it exceed the limits?”

No surprise; what happened is after legalization the prevalence of cannabis use, in those drivers that were tested, went up about two- to three-fold. If you’re going to predict which group was more likely to have the highest increase, I would have thought it was younger individuals. No, it was individuals 50 years and older. It was more likely to have a higher prevalence in males than in women.

Elizabeth: OK. Now that we have seen this association, what are the implications of this?

Rick: This just looks at prevalence of cannabis detection in these injured drivers. It doesn’t imply causality. Maybe cannabis is replacing alcohol use. That didn’t prove to be the case.

What they did mention is, they need to continue to have surveillance and they need to look at ways to put some teeth into it so that we have fewer people that are smoking and driving, and particularly older individuals. I mean, those are the ones whose cognitive abilities and reflexes decline. They need more, not less, psychomotor skills to be driving.

Elizabeth: Hmm. I’m wondering what the implications are going to be for this country.

Rick: Try to find more effective ways either through education or through other enforcement activities.

Elizabeth: More to come, no doubt. Let’s turn to JAMA. This is interesting news and good news. This is the use of two different diabetes drugs, semaglutide and liraglutide, in overweight adults to see whether or not it could result in weight loss. These folks who enrolled in this trial did not have diabetes.

The study was conducted at 19 U.S. sites and it enrolled people with a body mass index of 30 or greater, or 27 or greater with one or more weight-related comorbidities like hypertension, but who did not have diabetes — 338 folks, the majority of whom were women. They could either receive once weekly subcutaneous semaglutide at one dosage or a matching placebo, or once-daily subcutaneous liraglutide at a specific dosage or a matching placebo plus diet and physical activity. If they were unable to tolerate the higher dose, they could actually titrate down to a lower one.

They followed these people for quite a while, 68 weeks. Of this number, 319 completed the trial and here is what they found. The weight change from baseline was almost 16% less with semaglutide and 6.4% with liraglutide. Proportions of participants who discontinued treatment for any reason were about 14% with semaglutide and almost 28% with liraglutide. They also found that there were gastrointestinal adverse events, some of them serious, 84% approximately with semaglutide and 82% with liraglutide. In summation, I think it sure sounds like the semaglutide is the way to go and it’s probably worth trying.

Rick: Yeah. Elizabeth, both of these are in the same category of medications called glucagon-like peptide or GLP-1 receptor agonists. As you said, they are used for diabetes, but it was noticed that people that were diabetic and received them had weight loss, and they are now approved for weight loss in people without diabetes. As you said, there appears to be a clear winner. The one administered once weekly had more weight reduction.

By the way, there were other manifestations; it had a better reduction in blood pressure, a better reduction in triglycerides, and a better reduction in cholesterol as well. This is really the first large head-to-head comparison of these two medications.

The nice thing is that 5 out of 6 people that started the study with these medications continued use of the drugs and there weren’t such serious side effects that they had to stop them. I agree with you. This is a really good study that helps us determine in this particular agent group is one better than the other.

Elizabeth: It seems to me like it’s a strategy that’s well worth trying after we try first of all prevention, which we have talked about so many times.

Rick: Yeah. Another thing I should mention is that both of these groups had both diet and physical activity counseling as well. All of these things together help contribute. But a 15% weight loss is substantial. It’s the same amount of weight loss that oftentimes occurs following bariatric surgery and it’s what we are recommending — that there is a 5% to 15% weight loss — to receive the cardiovascular benefits.

Elizabeth: Good news. On that note, then, that’s a look at this week’s medical headlines from Texas Tech. I’m Elizabeth Tracey.

Rick: And I’m Rick Lange. Y’all listen up and make healthy choices.