Table 1. Baseline characteristics of matcheda cohorts (main analysis).
| TRD cohort | Non-TRD MDD cohort | Std. diff.b (%) |
Non-MDD control cohort | Std. diff.b (%) |
|
|---|---|---|---|---|---|
| N = 3,224 | N = 3,224 | N = 3,224 | |||
| Age at index date (years), mean ± SD [median] | 58.9 ± 14.6 [60] | 59.0 ± 14.6 [61] | 0.9 | 59.0 ± 14.6 [61] | 0.9 |
| Female, n (%) | 2,064 (64.0) | 2,052 (63.6) | 0.8 | 2,066 (64.1) | 0.1 |
| Race, n (%) | |||||
| White | 2,645 (82.0) | 2,671 (82.8) | 2.1 | 2,654 (82.3) | 0.7 |
| Black | 328 (10.2) | 326 (10.1) | 0.2 | 328 (10.2) | -- |
| Asian | 35 (1.1) | 25 (0.8) | 3.2 | 28 (0.9) | 2.2 |
| Other/Unknown | |||||
| Year of index date, n (%)c | |||||
| 2011 | 458 (14.2) | 457 (14.2) | 0.1 | 457 (14.2) | 0.1 |
| 2012 | 681 (21.1) | 679 (21.1) | 0.2 | 678 (21.0) | 0.2 |
| 2013 | 497 (15.4) | 490 (15.2) | 0.6 | 497 (15.4) | -- |
| 2014 | 475 (14.7) | 476 (14.8) | 0.1 | 473 (14.7) | 0.2 |
| 2015 | 516 (16.0) | 522 (16.2) | 0.5 | 521 (16.2) | 0.4 |
| 2016 | 470 (14.6) | 475 (14.7) | 0.4 | 470 (14.6) | -- |
| 2017 | 127 (3.9) | 125 (3.9) | 0.3 | 128 (4.0) | 0.2 |
| Geographical region, n (%) [27] | |||||
| Northeast | 543 (16.8) | 540 (16.7) | 0.2 | 545 (16.9) | 0.2 |
| Midwest | 809 (25.1) | 809 (25.1) | -- | 806 (25.0) | 0.2 |
| South | 1,308 (40.6) | 1,317 (40.8) | 0.6 | 1,312 (40.7) | 0.3 |
| West | 558 (17.3) | 555 (17.2) | 0.2 | 555 (17.2) | 0.2 |
| Unknown | <11 (<0.3) | <11 (<0.3) | -- | <11 (<0.3) | -- |
| Quan-CCI, mean ± SD [median] [28] | 1.4 ± 1.6 [1] | 1.3 ± 1.5 [1] | 6.6 | 1.0 ± 1.3 [1] | 28.9 |
| Top 5 most frequent physical comorbidities, n (%) [29]d | |||||
| Hypertension | 1,955 (60.6) | 1,902 (59.0) | 3.4 | 1,559 (48.4) | 24.9 |
| Diabetes | 924 (28.7) | 937 (29.1) | 0.9 | 795 (24.7) | 9.1 |
| Chronic pulmonary disease | 909 (28.2) | 799 (24.8) | 7.7 | 558 (17.3) | 26.2 |
| Deficiency anemias | 640 (19.9) | 575 (17.8) | 5.2 | 404 (12.5) | 20.0 |
| Hypothyroidism | 564 (17.5) | 537 (16.7) | 2.2 | 425 (13.2) | 12.0 |
| Top 5 most frequent mental comorbidities, n (%) [30] | |||||
| Depressione | 1,808 (56.1) | 1,947 (60.4) | 8.8 | 187 (5.8) | 129.6 |
| Anxiety disorders | 1,016 (31.5) | 879 (27.3) | 9.3 | 245 (7.6) | 63.2 |
| Sleep-wake disorders | 764 (23.7) | 658 (20.4) | 7.9 | 336 (10.4) | 35.9 |
| Substance-related and addictive disorders | 702 (21.8) | 613 (19.0) | 6.9 | 313 (9.7) | 33.6 |
| Other conditions that may be a focus of clinical attention | 500 (15.5) | 446 (13.8) | 4.7 | 235 (7.3) | 26.1 |
| Baseline costs and resource use | |||||
| Had ≥1 healthcare visit/service, n (%) | |||||
| Inpatient | 825 (25.6) | 705 (21.9) | 8.8 | 324 (10.0) | 41.5 |
| ED | 1,109 (34.4) | 961 (29.8) | 9.8 | 592 (18.4) | 37.0 |
| Outpatient | 3,030 (94.0) | 3,050 (94.6) | 2.7 | 2,848 (88.3) | 20.0 |
| Other | 1,729 (53.6) | 1,578 (48.9) | 9.4 | 1,454 (45.1) | 17.1 |
| Total healthcare costs (US $2017), mean ± SD [median] | 26,498 ± 57,243 [7,236] | 22,064 ± 54,182 [5,215] | 8.0 | 11,564 ± 27,935 [3,17] | 33.2 |
| Medical costs | 23,745 ± 56,246 [5,098] | 19,403 ± 52,085 [3,380] | 8.0 | 9,094 ± 25,439 [1,749] | 33.6 |
| Pharmacy costs | 2,753 ± 8,779 [950] | 2,661 ± 9,751 [697] | 1.0 | 2,470 ± 9,568 [543] | 3.1 |
Abbreviations: ED = emergency department; MDD = major depressive disorder; Quan-CCI = Quan-Charlson comorbidity index; SD = standard deviation; Std. diff. = standardized difference; TRD = treatment-resistant depression
Notes
aPatients were matched on propensity score (the probability of being in the TRD cohort vs. the non-TRD MDD or non-MDD cohort), generated using probability estimates from a logistic regression model adjusted for categorical age, sex, race, year of the index date, geographical region, and type of healthcare plan
bFor continuous variables, the standardized difference is calculated by dividing the absolute difference in means of the control and the TRD cohorts by the pooled standard deviation of both groups. The pooled standard deviation is the square root of the average of the squared standard deviations. For dichotomous variables, the standardized difference is calculated using the following equation where P is the respective proportion of participants in each group: (PTRD-Pcontrol)/√[(PTRD(1-PTRD)+Pcontrol(1-Pcontrol))/2].
cThe index date was defined as the date of the first prescription fill for an antidepressant.
dThe top 5 most frequent Elixhauser comorbidities identified in the TRD cohort were reported.
eDepression diagnoses included the following diagnoses ICD-9-CM: 296.2x (MDD—single episode), 296.3x (MDD—recurrent episode), 300.4x (dysthymic disorder), 309.0x (adjustment disorder with depressed mood), 309.1x (prolonged depressive reaction), and 311.x (depressive disorder, not elsewhere classified) or ICD-10-CM: F32x (MDD—single episode), F33x (MDD—recurrent episode), F341 (dysthymic disorder) and F4321 (adjustment disorder with depressed mood).