Rates of blood test ordering in general practice are increasing. It is known that different general practices request very different numbers of blood tests for patients. Part of this difference is because they care for different types of patients. A practice may have more older patients who are more likely to need blood tests to investigate their symptoms, or they may have more patients with long-term conditions which require regular blood tests e.g. diabetes, thyroid diseases. However, even after taking these factors into consideration, big differences in the number of blood tests ordered by general practices remain. It is possible that clinicians in some general practices are more inclined to request all types of blood tests when compared to others. This study aims to investigate whether this might be the case.
Firstly, we will identify the main types of blood tests ordered by general practices. Then, taking into account age, sex and number of patients with long-term conditions, we will find out if general practices tend to order more or fewer blood tests. Next, we will investigate whether general practices that order more or fewer blood tests in one year continue this trend over many years. Finally, we will investigate whether general practices that order more of one type of blood test also tend to order more of quite different types of blood test. It is important to try to understand this behaviour and this could help with techniques to improve the quality of blood test ordering in general practices.
There is considerable variation in blood test ordering behaviour between general practices. This variability has been found to be unrelated to the demographic, socioeconomic and case-mix factors of the practice. An alternative explanation is that variation may be explained by personal characteristics of clinicians or cultural characteristics of the general practices in which they work. This study is intended to understand variation in the ordering of diagnostic blood tests.
The study is a retrospective cohort study. Firstly, we will calculate the rate of blood test ordering in general practices and adjust for age, sex, case-mix and deprivation. We will then describe the trends over time to assess to what extent the rate of blood test ordering is and enduring characteristic of the general practice. Next, we will investigate whether there is any correlation of the rates of ordering between different types of test.
Variations in clinical practice have been a topic of interest to health services research for many years. Variations in blood test use have a number of important public health implications. Higher use of some blood tests may result in more rapid diagnosis of illnesses such as cancers and may be associated with better management of long-term conditions. On the other hand, higher use of some blood tests may result in patient harm through cascades of investigations or false positive results. It is therefore important to understand what factors drive higher or lower rates of diagnostic test use in order to investigate further and find out what underlies these variations. This is a first step in investigating whether general practices have distinct cultures or “personalities” in relation to their use of diagnostic tests in order to understand what an optimum diagnostic test rate would be and to consider how this might be optimised.
The primary outcome is the number of blood tests ordered by general practices.
Tom Marshall - Chief Investigator - University of Birmingham
Rachel Strudwick - Corresponding Applicant - University of Birmingham
Practice Level Index of Multiple Deprivation