Analysis in matched sets
Before matching, 1016 Group A patients moderately differed from 95984
Group B patients in a range of covariates (listed in Table 2) (Appendix,
Table A5), and 749 of the former could be exactly matched to 31336 of
the latter (Appendix,Table A5). All but one Group A patients and 86.2%
Group B patients were prescribed with at least one drug from the ATC
groups N05 (psycholeptics), N06 (psychoanaleptics) and N07 (other
nervous system drugs) at any time between January 1 2019 and the date of
the index COVID-19 diagnosis. Next, 866/1016 Group A patients could be
exactly matched to 222792/275804 Group C patients (Appendix , Table A6),
and 82323/95984 Group B patients could be exactly matched to
268778/275805 Group C patients (Appendix, Table A7).
Incidence of COVID-19-related hospitalizations and of COVID-19-related
mortality was <1.5% in all matched sets, while all-cause
hospitalizations were considerably more common (Figure 3). There was no
indication that outpatients prescribed fluvoxmine around the time of
COVID-19 diagnosis (Group A) were at a reduced risk of any of the
outcomes as compared to their peers burdened with similar psychiatric
difficulties but not prescribed fluvoxamine over the critical period of
time (Group B), or as compared to COVID-19 outpatients free of
psychiatric difficulties and related treatments (Group C) (Figure 3):
all relative risk estimates, frequentist and Bayesian with different
priors, were around 1.0 or somewhat higher than 1.0. Comparisons between
matched Group B and Group C patients were based on considerably larger
number of subjects than other comparisons (Figure 3), hence estimates
were much more precise (narrower confidence intervals), but in terms of
the point-estimates, A vs. C and B vs. C differences were closely
similar.