The clinical importance of variation in analyte mean values

In a previous blog we have discussed the variation in potassium results received from primary care across the year. This is mainly due to poor specimen stabilisation in low temperatures.

We have extended our analysis to compare primary care results with those taken in the Emergency Department (ED). Figure 1 shows this comparison.

Figure 1 Graph of mean monthly potassium in North Devon ED and all GP practices (winter months in pink)

In this figure we can see a few important things :

The monthly mean of potassium in the ED is stable.

In March 2018 the laboratory switched its analyser provider. This was associated with a clear shift in the mean monthly potassium result.

The median result of the individual GP practice means shows variation throughout the year

There appears to be a systematic difference between the ED and GP results.

In this series of blogs we will look at some of these issues in more detail.