Table 1. Patient characteristics of the total cohort of major depressive disorder (MDD) and the patient groups established by the TRD definitions: Karolinska Institutet Model (KIM), European Staging Method (ESM), Massachusetts General Hospital Staging Method (MGH-s), and Maudsley Staging Method (MSM).
| Anti-depressant initiator and MDD | KIM | ESM | MGH-s | MSM | p-value | ||
|---|---|---|---|---|---|---|---|
| n patients / n TRD patients | 127,108 | 16,453 | 12,059 | 24,112 | 19,486 | ||
| % TRD patients | 12.9 | 9.5 | 19.0 | 15.3 | <0.001c | ||
| Females (%) | 58.4 | 58.1 | 58.0 | 58.1 | 58.0 | 0.995c | |
| Age in years | 18–29 | 34.2 | 29.7 | 29.0 | 31.5 | 30.8 | <0.001d |
| 30–59 | 51.9 | 53.7 | 53.3 | 53.1 | 53.1 | ||
| 60–79 | 11.6 | 13.9 | 14.8 | 12.8 | 13.5 | ||
| ≥80 | 2.4 | 2.7 | 2.9 | 2.6 | 2.6 | ||
| Age in years, mean (SD) | 41.9 (17.1) | 42.4 (17.3) | 41.1 (17.1) | 41.5 (17.1) | |||
| Income (%)a | Low | 52.2 | 51.1 | 49.9 | 51.8 | 51.3 | 0.049c |
| Average | 45.1 | 46.3 | 47.3 | 45.5 | 46.0 | ||
| High | 2.7 | 2.6 | 2.8 | 2.7 | 2.7 | ||
| Country of birth (%) | Sweden | 79.9 | 79.3 | 79.9 | 79.8 | 79.6 | |
| Nordic country (excl. Sweden) | 2.6 | 3.0 | 2.8 | 2.9 | 2.9 | 0.867c | |
| Europe (excl. Nordic countries) | 7.0 | 7.8 | 7.3 | 7.4 | 7.6 | ||
| Other | 10.4 | 9.9 | 10.0 | 9.9 | 9.9 | ||
| Missing | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | ||
| Charlson Comorbidity Index (%) | 0 | 85.1 | 83.9 | 83.5 | 84.4 | 84.2 | 0.450c |
| 1 | 10.5 | 11.7 | 11.9 | 11.3 | 11.4 | ||
| >1 | 4.4 | 4.4 | 4.6 | 4.3 | 4.4 | ||
| TRD patients identified by other definitions (%) | 0–Exclusively identified by this definition | - | 0.0 | 0.5 | 34.1 | 16.0 | <0.001c |
| 1 –By one other definition | - | 1.8 | 0.1 | 1.4 | 2.4 | ||
| 2 –By more than one other definition | - | 30.4 | 7.0 | 18.3 | 24.5 | ||
| 3 –By all definitions | - | 67.7 | 92.4 | 46.2 | 57.2 | ||
| Days until TRDb | Mean (SD) | - | 78.2 (122.8) | 83.7 (123.5) | 73.3 (132.3) | 75.2 (121.3) | <0.001d |
| Median (IQR) | - | 69 (0–161) | 75 (0–168) | 60 (0–152) | 64 (0–158) | ||
a ‘Low’ income is defined as below the second decile (20) in the general population, ‘Average’ is between the second and the eight decile (20–80) of the general population and ‘High’ is above the eight percentile.
b Days from index date to being defined as a TRD. The index date is the date the patients had had both first filling of the antidepressant and a depression diagnosis; this is the explanation why a small number of patients got 0 days before TRD and not 3 X required length of treatment in the model.
c Chi-square test.
d One-way ANOVA.