Factors Associated with Blood Sample Haemolysis Rates in UK Health Foundation Trust with Particular Emphasis on Exposures that are Controllable via Evidence-Based Staff Training Package

  • Nellie Makhumula-Nkhoma

Student thesis: Doctoral Thesis


The overriding aim of the programme of research was to explore potential factors af-fecting the rates of pre-analytical blood sample haemolysis (PABSH). This was to in-form the design of an appropriate education and training package for clinicians. The experimental phase was based on intervention mapping framework. It includes three experimental chapters detailing a systematic review, a retrospective analysis of bio-chemistry blood results and an investigation into the influence of COVID-19 on PABSH.
The first study, a systematic review investigated the impact of venepuncture training on PABSH reduction. It showed heterogeneity in venepuncture training and inconclu-sive impact on PABSH rate reduction. There was also a lack of high-quality evidence as no randomised controlled trials were identified during the literature search. Variabil-ity in haemolysis rate detection and threshold setting made it impossible to conduct meta-analysis. The second study quantified haemolysis rates from 2017 biochemistry blood samples and explored influential factors in three acute assessment units (AAUs) in one UK National Health Service (NHS) Trust based in the North East of England. The Clinical Decisions Unit (CDU) is based off site in a small rural district hospital. The other two units, Acute Medical Unit, (AMU) and Acute Assessment Unit (AAU) are within the main hospital site. Haemolysis rate was highest (15%) in CDU compared to AMU and AAU, 11% and 12% respectively. Inflated haemolysis rate (24%) was also found in patients of age 95 years and above in the CDU. Irregular venepuncture train-ing and short sample transit time may have been the two most likely causes for the highest haemolysis rate in CDU.
A sub-study investigation of the influence of COVID-19 Disease on PABSH rates in the same three AAUs as in study 2 using interrupted time series (ITS) analysis, followed. The study replaced an initially planned Patient and Public Involvement (PPI) phase of the thesis and responded to the Medical Research Council (MRC) call to researchers to refocus their studies onto COVID-related issues. Biochemistry blood sample results from February 2019 to February 2021 were analysed. Daily haemolysis rate was used as the unit of analysis and the first lock down (23 March 2020) was set as the interven-tion date. The results showed a lack of association between COVID-19 and haemolysis rate. However, there was an inverse relationship between haemolysis rate and the number of events of blood sample analysis.
The PABSH causes reported in the above studies and current evidence were then graded using Grading of Recommendations, Assessment, Development and Evalua-tions (GRADE) framework. Following the Result-Based Management (RBM) catego-ries (input, activities, output, effect, and impact), a causal chain showing the impact the exposures have on PABSH, was drawn-up. The causal chain allowed the design of an evidence-based venepuncture education and training package. A proposal for a pilot cluster randomised controlled trial (cRCT) was then designed to enable the investiga-tion of the impact of the proposed training package on PABSH rate. The cRCT proposal design respond to the finding highlighted in the systematic review, that of lacking high-quality evidence in the subject area.
To achieve a reduction in PABSH there is need for an evidence-based education and training package integrated into practice. Furthermore, it is of great importance that the multidisciplinary team is involved in close monitoring of the education and training and in the conduct of venepuncture. Such involvement would enhance timely process and outcome evaluation in the overall venepuncture services.
Date of Award9 May 2023
Original languageEnglish
Awarding Institution
  • Teesside University
SupervisorSamantha Harrison (Supervisor) & John Young (Supervisor)

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