Things aren’t always what they seem.
Here are two examples of ‘maybe not’ in relation to diagnostic screening.
On first appearances it seems that there would be no doubts that most screening proposed would make a difference.
But when examined closely, these two studies did not support the medical diagnosis as they should have.
Aaron Carroll, The Incidental Economist, applies four questions when discussing a screening test.
- Is the condition prevalent and severe enough to warrant screening?
- Do we have a cost-effective means to screen the general population
- Does early diagnosis make a difference (that is, do we have treatments available that are more successful when patients are diagnosed earlier?)
- Will an early diagnosis motivate people to use information gained from screening?
The BMJ reported upon the systematic review of studies that looked at the accuracy of tests used to identify pre-diabetes.
The study then reviewed the efficacy of the interventions used to to prevent diabetes.
In an astounding finding, it found the A1C marker that was being tested to identify pre-diabetes could not be relied upon.
Half of the people with an abnormal A1C didn’t have any glycemic abnormalities.
So there is no screening test for pre-diabetes that can be trusted.
That means that it’s both missing people who have prediabetes and putting people who don’t into interventions they may not need.
Since more intervention programs try and get people to adopt healthier lifestyles, there’s little harm in getting them to eat better and be more active. Some trials put people on metformin, though, and that does come with side effects. They all involve costs, too.
In a similar vein, JAMA has reported about an asthma study by Canadian researchers.
They wanted to know whether a diagnosis of asthma could be ruled out after a period of time.
And whether asthma medications could be safely stopped.
This study reviewed 613 people that had been diagnosed with asthma over the previous five years.
(O)ver four visits they gave them a series of drug challenges and spirometry, a physical test of breathing capacity, to confirm or rule out the disorder.
The researchers were able to rule out the diagnosis of asthma in 33% of the participants.
Some patients ( 2%) had been misdiagnosed and some (29.5%) had no clinical or laboratory evidence of asthma.
Needless to say the researchers concluded that patients with physician- diagnosed asthma who were not using daily asthma medications or had been weaned, should have their diagnosis reassessed.
To learn more about diabetes and asthma click here: