Is Medical Imaging a Ricardian Derived Demand?


Medical Imaging and the Price of Corn

After the Napoleonic wars, the price of corn in England became unaffordable. The landowners were blamed for the high price, which some believed was a result of the unreasonably high rents for farm land. Economist David Ricardo disagreed.

According to Ricardo, detractors had the directionality wrong. It was the scarcity of corn (the high demand relative to its supply) that induced demand for the most fertile land. That is, the rent did not increase the price of corn. The demand for corn raised the rent. Rent was a derived demand.

Directionality is important. Getting directionality wrong means crediting the rooster for sunrise and blaming umbrellas for thunderstorms. It also means that focusing on medical imaging will not touch healthcare costs if factors more upstream are at play.

Medical imaging is a derived demand. The demand for healthcare induces demand for imaging. Demand is assured by the unmoored extent to which we go for marginal increases in survival.

The Demand for Imaging in Stroke

The treatment of ischemic stroke using thrombolytics and intra-arterial therapy (IAT) is instructive on how imaging can be induced. Lytics improve outcomes but must be administered relatively rapidly after onset of symptoms. IAT, which is treatment at the site of arterial blockage, allows the clock to tick for a bit longer and has recently been shown to be beneficial.

In the MR CLEAN[1] study, patients with acute ischemic stroke with radiographically proven occlusion in the proximal anterior circulation were randomly assigned to IAT or usual care. IAT included local thrombolysis, mechanical break up of thrombus, or stent placement. In both treatment and control groups, most patients also received thrombolysis with alteplase (Activase®).

The results published in the New England Journal of Medicine[1] showed that patients who received IAT within 6 hours of stroke onset had a clinically significant increase in functional independence at 3 months without higher mortality.

Counting the CTs and CT Angiograms

However, patients don’t walk into the emergency department saying, “Good evening, doctor, I have an occlusion in the proximal internal carotid artery. Can we get moving, please?” Sometimes they have classic signs and symptoms of stroke in the distribution of the target artery. Often they have more vague signs and symptoms that could be due to other causes.

(Read more here)

Saurabh Jha, aka @RogueRad, is a contributing editor to THCB and host of Firing Line Podcast.

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7 replies »

  1. Most of the symptoms are lifestyle associated, for which one visits to the clinician. In modern practice, a visit to clinician often results in a prescription with some diagnostic test, prophylactic (preventive) pills (disease for which symptoms) to attain health. The prescription fulfills the mutual desire that ‘‘something be done’’ to ritually and therapeutically justify the visit. The patient tracks down the prescription and struggles to remember to take them on time, and also pay-off for them to restructure their lives. Continue reading…

  2. Dr Itua Cure my Hiv withing two weeks of drinking his Herbal Medicine,His contact…..drituaherbalcenterATgmail.com

  3. This has made budgeting for many people difficult. I need to have someone always available for one of these procedures on short notice. These are fairly sick patients and the procedure is not especially quick. However, we don’t know when they will occur, and it costs money to have someone just hang around waiting to do these. These are mostly Medicare patients so it doesn’t pay well. The true costs for this care are going to be pretty high.


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