2.2 Case Series
The majority of the remaining studies present case series. They present
similar cross-sectional evidence to the questionnaire designed studies
with a common aim of investigating the symptomology of anosmia in the
COVID-19 era. This approach should contribute to limiting the level of
bias in their results when compared to an outcome-based case series but
they are similarly only able to demonstrate association and not causal
effect. The complementary data output, between the questionnaire and
case-series approaches, allows us to compare the two approaches
concurrently in a meta-analysis.