The Covid-19 pandemic resulted in significant amount of illness and death worldwide. During the pandemic, governments instituted lockdowns, widespread testing and vaccination. Several new drugs were proposed to prevent Covid-19 infection, with four newly developed drug therapies being approved in the UK for prevention of severe disease in those who are at most risk. These drugs have been developed at high cost hence the restriction to those who are most likely to benefit.
Ursodeoxycholic acid (UDCA) has been investigated as a possible drug with the potential to prevent Covid-19 in people. UDCA is an inexpensive drug prescribed in those suffering with stones from the gallbladder or those with a condition called primary biliary cirrhosis, which is a liver disease caused by the body's immune system attacking the ducts that drain bile from the liver. UDCA is generally safe and well tolerated. The possibility that it may prevent Covid-19 has resulted in widespread use in China where public concern due to Covid-19 is still high due to less vaccination coverage in the elderly and fewer intensive care beds per head of population. The effectiveness of UDCA in preventing Covid-19 has not been widely investigated but has the potential of being an inexpensive preventative medication. Studying this in a restricted real life population will help investigate whether there is rationale behind UDCA use for persons concerned about Covid-19 infections.
This study aims to study the association between adherence to UDCA prescriptions and the incidence of Covid-19 as documented in primary care.
The study population of interest includes patients that have been recorded as having been prescribed UDCA during the study period. The primary exposure is adherence to UDCA as measured by the proportion of days covered, calculated by the length of the prescription in days divided by the days within the study period. This selection represents patients with similar health conditions that require treatment with UDCA and allows for patients with no prescriptions during the study period to be part of the study population.
This study will take place over 2 outcome phases. 1) 30 June 2020 to 31 December 2020 corresponding to the start of the pandemic and pre-vaccination. 2) 1 July 2020 to 30 May 2021 corresponding to the start of vaccinations to lifting of outdoor restrictions lifted to allow 30 people to mix.
Eligible patients will need to be registered prior to the start of the study period. Patients who register after the start of the study period will not be eligible. Patients who become unregistered or have a death date after the start of the study period will be included.
The study will be a comparative retrospective cohort study where the exposure will both be considered as a continuous (adherence as measured by the proportion of days covered) and categorical (low adherence, high adherence, with the boundary of 80% or over as the differentiator for high adherence) measure.
The recording of COVID-19 within the primary care record will be the primary outcome and will be tested with logistic regression analysis taking into account other covariates that have been listed by the NHS as increasing susceptibility to the Covid-19 virus will be included as confounders.
The outcomes that are measured are described in CPRD Aurum SARS-CoV-2 code list provided in the CPRD data highlights.
Positively tested/diagnosis of COVID-19 include codes that cover 'code types' that include 'Diagnosis', 'Tested/Diagnosis'. 'Possible', 'Tested', 'Vaccination' and 'Advice' will not be considered as a positive diagnosis. Codes for these code types are provided in reference 9. Incidence of tested/diagnosis and diagnosis will be considered as a single outcome indicating positive diagnosis. Time until diagnosis will not be considered.
Simon Wan Yau Ming - Chief Investigator - Health iQ Ltd ( UK ) t/a CorEvitas
Simon Wan Yau Ming - Corresponding Applicant - Health iQ Ltd ( UK ) t/a CorEvitas
Mike Smith - Collaborator - Health iQ Ltd ( UK ) t/a CorEvitas
Mike Smith - Collaborator - Health iQ Ltd ( UK ) t/a CorEvitas