Immortal time bias for life-long conditions in retrospective observational studies using electronic health records.

ABSTRACT:

Background

Immortal time bias is common in observational studies but is typically described for pharmacoepidemiology studies where there is a delay between cohort entry and treatment initiation.

Methods

This study used the Clinical Practice Research Datalink (CPRD) and linked national mortality data in England from 2000 to 2019 to investigate immortal time bias for a specific life-long condition, intellectual disability. Life expectancy (Chiang's abridged life table approach) was compared for 33,867 exposed and 980,586 unexposed individuals aged 10+ years using five methods: (1) treating immortal time as observation time; (2) excluding time before date of first exposure diagnosis; (3) matching cohort entry to first exposure diagnosis; (4) excluding time before proxy date of

SUBMITTER: Tyrer F 

PROVIDER: S-EPMC8962148 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature