Among the 280 patients, two (0.7%) refused to fill in the MADRS-S questionnaire and were excluded from the analyses. The mean patient age was 45.2 ± 11.0 years, 186 (66.9%) were females, 188 (67.6%) had a professional activity, and 218 (78.4%) lived in an urban area. One hundred and sixty-seven patients (60.1%) were recruited by psychiatrists; 137 patients (49.3%) were treated with escitalopram and the remaining 141 (50.7%) received citalopram.
Clinical characteristics are presented in Table . More than half of the patients were experiencing their first episode of MDD, while 46 (16.5%) had a history of psychiatric hospitalisation. Overall, patients had a mean MADRS of 35.9 and a mean CGI-S of 5.1; 57.6% were rated as severely ill (MADRS ≥ 35).
Patients' clinical characteristics at baseline.
No missing values were observed, indicating a high level of patient acceptability of the questionnaire. With the exception of items 4 (appetite), 7 (emotional involvement) and 9 (zest for life), item response distributions had a higher ceiling rather than floor effect, highlighting the initial severity of the disease (Table ). Item-scale correlations showed that all but one item (8, pessimism) achieved the standard value of 0.40 for item-internal consistency (Table ).
Descriptive Statistics of the 9 MADRS-S Items and Total Score.
The results of the factor analysis confirmed the unidimensionality of the MADRS-S: each item contributed to the first factor axis with a factor loading of at least 0.50, explaining 45% of the total variance.
The MADRS-S score was moderately correlated with physicians' severity ratings (MADRS-S with MADRS: r = 0.54, p < 0.001; MADRS-S with CGI-S: r = 0.38, p < 0.001). As expected, the MADRS-S total score did not discriminate as to whether a patient was suffering from their first episode of MDD, nor if they had a history of psychiatric hospitalisation, but did discriminate as to whether a patient's baseline severity was ≥ 35 in the current episode (Table ).
Clinical Discriminative Validity of the MADRS-S.
The ROC curve for perceived remission is displayed in Figure . Using the cut-off value of 5, the MADRS-S-based definition of perceived remission reached a sensitivity of 81.8%, a specificity of 75.4%, and positive and negative predicted values of 77.1% and 80.3%, respectively.
Receiver Operating Characteristic Curve for Perceived Remission. CO: cut-off value for MADRS-S score.
Internal consistency reliability of the MADRS-S was satisfactory, with a Cronbach's alpha of 0.84, allowing group comparisons. The deletion of any of the 9 items would not increase the internal consistency of the total score (Table ).
Among the 120 patients whose CGI-I at week 1 was rated "No change" by physicians, the intraclass correlation coefficient was 0.78, indicating the satisfactory test-retest reliability of the MADRS-S.
Sensitivity to changes
In the sub-sample of 132 remitter patients (i.e. those whose MADRS total score at week 8 was less than or equal to 12), a statistically significant difference of -12.4 ± 4.2 points was found for the total MADRS-S between baseline and week 8. This difference led to an effect size of 2.8, which supported the sensitivity to change of the self-reported version of the MADRS.
When comparing the antidepressant effects of the two therapeutic strategies of the trial, we found that the mean MADRS-S score changes from baseline were in favour of escitalopram (-9.9 ± 5.1 for escitalopram versus -8.6 ± 5.9 for citalopram), the mean difference of 1.3 (standard error of 0.7) being statistically significant (p = 0.046). As a comparison, a mean MADRS difference of 2.1 was found between escitalopram and citalopram (p < 0.05).
Perceived response, defined as a reduction of at least 50% of the baseline MADRS-S score, and perceived remission, defined using the optimal cut-off value of 5 found in the ROC analysis, were also significantly in favour of escitalopram (Figure ). Perceived response rates were 66.4% and 53.9% for escitalopram and citalopram, respectively (p = 0.033). Perceived remission rates were 49.6% and 37.6% for escitalopram and citalopram, respectively (p = 0.043). As a comparison, response rates based on investigators' ratings of the MADRS were 76.1% for escitalopram and 61.5% for citalopram (p = 0.009); remission rates were 56.1% and 43.6% for escitalopram and citalopram, respectively (p = 0.040).
Perceived Response and Perceived Remission at Week 8.