Publications

Objectives

Laboratory testing has increased dramatically over the last decades, with repeat testing being a major
contributor. However, much of the increase in laboratory utilisation may be unnecessary, particularly
for repeat testing.

Method

Within a single region in the UK (Oxfordshire) we assessed the rates of initial and monitoring lipid
measurements (total cholesterol, HDL, and triglyceride) from electronic records covering the last 20
years. All tests which were the third or more in a three-year period were considered to be for
monitoring, either of response to treatment or follow-up. We related the number of total cholesterol
tests requested to dates of key publications and guidelines.

Results

Over the 20 years from 1987, there was a more than 15-fold rise in the overall number of tests
requested (total cholesterol, triglycerides, and HDL cholesterol). After a drop in the early 1990's a
steady rise commenced after publication of several large statin trials, with most of the increase arising
from tests requested in primary rather than secondary care. Repeat testing (assumed to be monitoring)
rose from 24% of the tests between 1993 and 1995 to 61% between 2005 and 2007, with more than
half of these tests (190,000, 56%) possibly being unnecessary. Mean cholesterol values were lower in
males, increased per decade of age until 60 or 70 years and then decreased, and declined over time
from 1996 onwards.

Conclusions

The number of cholesterol tests performed in Oxfordshire fell briefly then rose dramatically during the
past 20 years, with a 10-fold increase overall. The fall and rise appear to closely follow the publication
of systematic reviews and trials. Given the advent of statin treatment, the rise is generally appropriate.
However, much of the rise appears to be for monitoring purposes rather than case finding or risk
assessment. Given that frequent monitoring of cholesterol may reflect measurement error rather than
true changes, the majority of cholesterol tests requested may be unnecessary.