  With the increasing breaches and security threats that endanger health data,
ensuring patients' privacy is essential. To that end, the research community
has proposed various privacy-preserving approaches based on cryptography,
hashing, or ledger technologies for alleviating health data vulnerability. To
establish a comprehensive understanding of health data privacy risks, and the
benefits and limitations of existing privacy-preserving approaches, we perform
a detailed review of existing work and distill 10 distinct privacy concerns
occurring in a health data lifecycle. Furthermore, we classify existing
approaches based on their applicability to particular privacy concerns
occurring at a particular lifecycle stage. Finally, we propose a taxonomy of
techniques used for privacy preservation in healthcare and triangulate those
techniques with the lifecycle stages and concerns. Our review indicates heavy
usage of cryptographical techniques in this domain. However, we have also found
that healthcare systems have special requirements that require novel
cryptographic techniques and security schemes to address special needs.
Therefore, we identify several future research directions to mitigate the
security challenges for privacy preservation in health data management.
