I’m a pathologist, which means that I run the lab, and I’m continually shocked by all the unnecessary lab work that comes my way. Doctors have to find something wrong with you, because preventative measures aren’t sexy. They know that you’re more likely to appreciate them if they tell you something’s wrong, than if they tell you to stop drinking 40 oz sodas. Humans of New York
This week a report was released that documents changes in Australian GPs’ ordering of X-rays and scans in the decade 2002- 2012. The report includes an evaluation of the quality of GP test ordering against available guidelines. The team compared two periods: Apr 2002- March 2005 inclusive (Period 1) and April 2009 to March 2012 inclusive (Period 2). Three factors were found to be relevant:
- The number of encounters between doctors and patients
- The number of problems managed at encounters
- The rate of ordering tests in the management of problems encountered
It was not surprising that people are attending doctors more often and that they are presenting more problems than before. However the rate of imaging tests ordered significantly increased from 8.7 per 100 encounters in Period 1, to 10.2 per 100 in Period 2. Extrapolation of this result suggests an average 8.45 million imaging tests ordered by GPs per year in Period 1 and 12.23 million per year in Period 2, an increase of 44.7%, equating to approximately 3.78 million more orders per year over the 3 years in Period 2 than in the years of Period 1. With respect to the guidelines current ordering behaviour for new back problems, shoulder sprains/strains, knee problems, and knee sprains/strains, has room for improvement, according to the researchers. The results were not entirely unexpected. There has long been a concern about unnecessary test ordering. In a paper published in 2008 unnecessary laboratory tests may be defined as those that have a ‘vanishingly small’ chance of:
- revealing any unexpected pathological process.
- contributing to the diagnosis of the cause of a patient’s presenting symptoms.
- assisting in the monitoring of the progress of a known pathological process.
- helping to assess the management of a known disease process.
An interesting insight is offered:
The millions of dollars spent on unnecessary tests are, in [doctors’] minds, balanced against the tens of millions involved in adverse court judgments.
In this context I recently asked colleagues what test they would perform on me if I presented as ‘tired all the time’, adding that I had no physical signs, was not depressed and was not taking anything (prescribed or otherwise) that would account for my fatigue. The answer was unanimous-‘Thyroid function test’. This was based on published advice on the approach to such patients:
However, even though laboratory evaluations rarely play a crucial role, they should be used to exclude underlying organic illness.
So, I asked my colleagues how they would interpret the findings if my results were found to be just over the limit of normal. What, in their view was the probability that I have hypothyroidism? ‘High’ came the answer. ‘We would put you on thyroxine.’ The published data suggests that the positive predictive value of tests on people in this context is less than 12%. Which means it is highly unlikely that I have anything physical wrong with me, much less that I need to take thyroxine. At a time when there is an increasing demand for GP services, it is going to be helpful for colleagues to be aware of the positive predictive value of the tests they order and to share that information with patients before recommending tests. The article listing laboratory tests to screen for a host of highly unlikely conditions assumes that the doctor has spoken to and examined the patient and that the indications for the tests are based on specific clinical findings. In most cases the patient who has a life limiting pathology does not look or feel well. However every patient needs to know what the test results mean- they are often meaningless and place the patient in harms way. The approach in the Dutch paper to postpone tests for 4 weeks resulted in benefit to people with unexplained fatigue who may otherwise have been harmed by further investigation of equivocal test results. The study is testimony to what can be achieved by practitioners sharing information with patients while harnessing the power of observation, applying a little bit of science and dispensing a tincture of common sense.
Picture by Send me adrift.