Screening

You are currently browsing articles tagged Screening.

Regional Variation in Diagnosis Frequency

May 18, 2010 in Medicaid/Medicare, Supply of Medical Services | 1 comment

For many years, the Dartmouth Atlas has chronicled how variation in medical resource use across the country.  Despite glaring differences in the cost and volume of care across the nation, regions with higher health care costs do not necessarily have better health outcomes.

However, medical treatment is a two step process.  First, the physician must diagnose a disease, and next the physician must decide the course of treatment given the disease the patient is assigned.  Thus, the reason regions have more intensive use of medical services could be 1) they are more likely to diagnose patients as having a more severe disease, or 2) they are more likely to use more expensive medical services in the treatment of that disease.

A recent paper in the New England Journal of Medicine does find that there is significant regional variation in how patients are diagnosed.  Simply examining regional variation in diagnoses may simply indicate that one region has more sick people than another.  To get around this problem, the authors examine what happens when Medicare beneficiaries move.  As people age, they are more likely to become sicker and thus accumulate more diagnoses.  However, individuals who moved to high cost regions were more likely to acquire more and more serious diagnoses than those who moved to lower cost regions.

To determine diagnose severity, the authors used Hierarchical Condition Categories (HCCs)–which Medicare uses as a risk adjustment mechanism to reimburse Medicare Advantage managed care plans–to create a risk score. Ranking individuals by risk score quintile,  this chart clearly shows a trend that when individuals move to higher cost regions, they are more likely to accumulate more diagnoses and increase their HCC risk score.

The authors conclude by pointing out the following:

“A major concern about both payment reforms and performance-measurementinitiatives is their potential for adversely affecting behavior. For example, if providers are more highly compensated for treating patients with more diagnoses, they could conceivably be inclined to perform more intensive screening and diagnostic testing, with clear effects on costs and uncertain effects on health outcomes.”

Tags: , , , , ,

The paradox of better screening

December 12, 2008 in Economics - General | No comments

Does better screening lead to improvements in health outcomes?  Conventional wisdom holds that this is always true.  For instance, catching breast cancer at an early stage greatly improves survival probabilities.  However, early screening can lead to a statistical anomaly where better screening appears to improve mortality rates even when treatments are entirely ineffective.

Here is an example using the dreaded disease economicitis.  Let us divide people into 3 groups.

  • Healthy: You live forever.
  • 1st stage economicitis is asymptomatic. Life expectancy when 1st stage economicitis begins is 10 years.  One half of economicisits cases are 1st stage.
  • 2nd stage economicitis appears when individuals mysteriously grow a third or possibly fourth hand.  Life expectancy with second stage economicitis is 2 years.  One half of economicitis cases are 2nd stage.

Before any screening was developed, individuals would learn they had  economicitis  when they started growing extra hands.  Thus, documented life expectancy for those with  economicitis was 2 years, since all individuals who were recorded as having  economicitis were in the 2nd stage.

Let us assume that a screening technique is now available.  If the screening device is able to detect 100% of stage 1 and stage 2 economicitis cases, then we will see that life expectancy will increased to 6 years (10/2+2/2=6). Statisticians looking at the data may claim the following: “The economicitis screening test has increased life expectancy after diagnosis from 2 to 6 years!”

This claim, however, is false since there is no effective treatment for  economicitis.  The increase in average life expectancy is not due to any improvement in health care, but only because the relatively healthier individuals with 1st stage economicitis are now being detected by the test.

Tags: ,