Addressing the Healthy Donor Effect while Studying the Impact of Blood Donation on Donors' Long-Term Health Outcomes
- Publication Type:
- Thesis
- Issue Date:
- 2023
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𝗕𝗮𝗰𝗸𝗴𝗿𝗼𝘂𝗻𝗱
The healthy donor effect (HDE) is a methodological problem that arises in donor health research when comparing donor versus non-donor or regular donor versus casual donor. This may distort the true causal relationship between blood donation and long-term health outcomes.
𝗔𝗶𝗺𝘀 𝗮𝗻𝗱 𝗢𝗯𝗷𝗲𝗰𝘁𝗶𝘃𝗲𝘀
The aim of this thesis was to identify and apply the method/s to provide an unbiased estimate of the impact of blood donation on blood donors' long-term health outcomes (all-cause mortality and some cancers).
𝗠𝗲𝘁𝗵𝗼𝗱𝘀
I conducted a systematic review to identify and summarised the methods that were used to account for the HDE in published studies. I then applied a causal inference method called ‘target trial emulation’ and another less biased method called ‘exposure window’ method to adjust for the HDE using the Sax Institute’s 45 and Up Study data, linked with blood donor data and other health data sets. For all-cause mortality, I used both the target trial and 5-year exposure window methods, along with adjustments from g-methods (inverse probability weighting, targeted minimum loss-based estimator, and sequentially doubly robust estimator). I also investigated the association of regular blood donation with gastrointestinal, colorectal, and haematological cancer using the 5-year exposure window method.
𝗥𝗲𝘀𝘂𝗹𝘁𝘀
The results from the systematic review suggested that most of the existing methods used to mitigate the HDE were inadequate to effectively address this bias. A lack of use of appropriate causal inference techniques was also observed. In my analyses, the target trial emulation technique did not show any statistically significant association between the initiation of blood donation and the mortality risk. The use of the 5-year exposure window method also did not reveal any significant relationship between higher-frequency blood donation and all-cause mortality when compared to lower-frequency donors. For gastrointestinal and haematological cancers, I also found no statistically significant difference in the risk of cancers for the higher-frequency blood donors compared to the lower-frequency donors.
𝗖𝗼𝗻𝗰𝗹𝘂𝘀𝗶𝗼𝗻
Through a systematic review, I found that the methods used in blood donor research to mitigate the impact of HDE are inadequate. Using some of the less biased methods, I found no significant association between regular, higher-frequency blood donation and long-term health outcomes such as mortality and some cancers after adjusting the HDE. The findings from this study can provide crucial insights for the Australian Red Cross Lifeblood’s strategic planning and directing future research.
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