3.2 Additional effectiveness analyses
To explore the relations between demographic and clinical
characteristics and the observed clinical effectiveness of agomelatine
on depression we performed several linear regression analyses. The
following characteristics were selected as covariates of interest: age,
sex, severity of depressive disorder at baseline according to HAMD-17
total score, COVID-19 severity, and time passed since COVID 19 infection
onset. Univariate regression analysis showed that depression severity at
baseline (regression coefficient: -0.741; P<0.0001), moderate
severity COVID-19 (regression coefficient: -3.395; P=0.0035), and time
since onset of infection (regression coefficient: -2.395; P=0.0006) were
the parameters with a statistically significant relationship with the
observed decrease in HAMD-17 total score at the end of follow up (week 8
visit). All coefficients were negative indicating that the relations
between these parameters and the observed improvement in depression
severity were reciprocal. However, after multivariate regression
analysis the only parameter remaining significantly related to
improvement in depression severity at week 8 was baseline depression
severity expressed as total HAMD-17 score (regression coefficient:
-0.70; P<0.0001). When univariate regression analyses were
conducted to explore relations between the covariates of interest and
the effectiveness of agomelatine at reducing anxiety severity and
improving patients’ QoL, mean total HAMD-17 score at baseline was again
the only parameter with a significant relation with the observed
improvement in both anxiety and patients’ QoL (Table 2 ).