Project #30:
Pathology Comparators Short Report.

In this study we will investigate how blood test results can be interpreted in OpenSAFELY. Blood test results give us important information about someone’s health. However, for some tests, the values can be reported as “less than” or “more than” a threshold, typically for values outside the accurate range that the machine can detect. Therefore a test result may appear as “<10”, and for some tests this type of result is very common. However, when conducting research, researchers may wish to group patients together and if the comparators (< and >) are not taken into account we may group the values incorrectly, e.g. the “<10” above would be taken as “10” and incorrectly grouped with values “>=10”. Here we will identify which tests involve comparators most often, and which values they are typically associated with. For example, if a certain test often has values “>5.5” then when creating groups researchers might need to use 5.5 as their highest value. The findings of this audit will be useful in various context, for example (a) assessing patients’ severity of preexisting disease, which may impact their risk from COVID, (b) assessing the impact on patients’ health after contracting COVID or (c) assessing indirect impacts of COVID on healthcare provision (e.g. whether people with diabetes generally experienced worsening disease during the pandemic).