Clinical trial NCT05252442: Association of the Risk for Thrombotic Thrombocytopenia Syndrome and Exposure To COVID-19 Vaccines
Official title: An Assessment of a Relationship Between the Exposure to COVID-19 Vaccines and Risk of Thrombotic Thrombocytopenia Syndrome ATTEST Study (Association of the Risk for Thrombotic Thrombocytopenia Syndrome and Exposure To COVID-19 Vaccines)
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Covid-19
Lead sponsor: AstraZeneca
Sponsor class: INDUSTRY
First posted: 2022-02-23
Enrollment: 7641136
Sex: ALL
Minimum age (years): 16
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: OTHER
Sampling method: NON_PROBABILITY_SAMPLE
Study population: COVID-19 vaccinated English population with in one study historic and concurrent controls; and in the other a self-controlled case series.

Brief summary: Background/Rationale: A very rare syndrome of thrombosis associated with low platelets has been reported in a few cases of recent exposure to COVID-19 vaccine. This thrombotic thrombocytopenia syndrome seems to be affecting patients of all ages and both genders; at present there is no clear signal of risk factors.

Objectives: To evaluate an association between COVID-19 vaccine exposure and thromboembolic events occurring with thrombocytopenia (thrombotic thrombocytopenia syndrome; TTS).

Study design: Two primary study designs will be considered, a case control study and a self-controlled case series (SCCS). A cohort analysis will be considered, in addition or as an alternative to either of the primary study designs, pending feasibility assessment of the follow-up time.

Data Source(s): Data for the study will be accessed through the NHS Digital Trusted Research Environment (TRE), providing national data coverage. Primary care data will be linked with vaccination, hospitalization, COVID-19 test results, mortality data. Initial exploratory analyses will be conducted using the Oxford-Royal College of General Practitioners sentinel network; ORCHID network database (N\>15million).

Subjects of interest are patients who have received a COVID-19 vaccine. However, investigators will require access to data from all subjects in the databases.

Statistical Analysis: The study period will start on December 02, 2020, when the COVID-19 vaccine was first approved in the UK and will end at the end of data availability.

For the case-control design, all cases of TTS will be matched with control using risk-set matching. A case or matched control will be considered exposed if a COVID-19 vaccination will be within risk interval prior to the diagnosis date of the matched case.

For the SCCS, estimates of relative incidence (RI), in all risk intervals will be reported.

For the retrospective cohort design, the incidence of TTS after receiving COVID-19 vaccine will be estimated and investigators will compare this incidence with that occurring in an unvaccinated comparator group about levels of infection across the whole population.

Variables: Demographic, socioeconomic descriptors, clinical diagnosis, vaccines, potential confounders, thrombotic phenomena, COVID-19 infection, and other characteristics as applicable.


Eligibility criteria: Inclusion Criteria:

* A minimum of 12 months medical history prior to the start of the study period

Exclusion Criteria:

* Less than 12 moths medical history prior to the start of the study period

Primary outcomes:
measure: thrombotic thrombocytopenia syndrome; TTS
timeFrame: 9 months
Secondary outcomes:
Other outcomes:
Locations:
city: Oxford
country: United Kingdom
facility: Research site
Study officials:
References: