Background rate estimations for thrombosis with thrombocytopaenia: challenges in evaluating rare safety signals following vaccination in real time during a pandemic.
BMJ Open
; 13(1): e063645, 2023 01 13.
Article
in English
| MEDLINE | ID: covidwho-2193770
ABSTRACT
OBJECTIVES:
During COVID-19 vaccination programmes, new safety signals have emerged for vaccines, including extremely rare cases of thrombosis with thrombocytopaenia syndrome (TTS). Background event rates before and during the pandemic are essential for contextualisation of such infrequent events. In the literature, most studies do not report an overall TTS event rate. Rather, background rates are mainly reported for subtypes of thrombotic/thromboembolic diagnoses included in the TTS clinical definition mostly by anatomical location, with reported rates for TTS subtypes varying widely. The objective of this study was to report prepandemic TTS background event rates in the general population.METHODS:
Prepandemic background TTS rates were generated via secondary data analysis using a cohort design in the IBM Truven MarketScan (now Merative MarketScan) US health insurance claims database, from 1 January 2019 to 31 December 2019. Two algorithms were applied thrombocytopaenia occurring±7 days (algorithm 1) or occurring 1 day prior to ≤14 days after the thrombotic/thromboembolic event (algorithm 2).RESULTS:
The study population derived from the MarketScan database analysis included approximately 9.8 million adults (aged ≥18 years; mean age 45 years, 52% females). Using this study population, prepandemic background TTS incidence was estimated as 9.8-11.1 per 100 000 person-years. Event rates were higher in males and increased with age. Similar patterns were observed with both algorithms.CONCLUSIONS:
This study presents an estimate of aggregate prepandemic background TTS event rates including by type of thrombosis/thromboembolism and age group. The background event rates are dependent on the precision of capturing underlying TTS events in variable data sources, and the ability of electronic health records or insurance claims databases to reflect the TTS clinical definition. Differences between reported event rates demonstrate that estimating background event rates for rare, unprecedented safety events is methodologically challenging.Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
Thrombocytopenia
/
Thromboembolism
/
Thrombosis
/
COVID-19 Vaccines
/
COVID-19
/
Anemia
Type of study:
Cohort study
/
Experimental Studies
/
Observational study
/
Prognostic study
Topics:
Vaccines
Limits:
Adolescent
/
Adult
/
Female
/
Humans
/
Male
/
Middle aged
Language:
English
Journal:
BMJ Open
Year:
2023
Document Type:
Article
Affiliation country:
Bmjopen-2022-063645
Similar
MEDLINE
...
LILACS
LIS