Table 3.
Independent variables significantly associated with changes in HRQoL from baseline to 6 months
| Independent variables | SF-36 MCS | SF-36 PCS | EQ-5D health state value | EQ-5D VAS | ||||
|---|---|---|---|---|---|---|---|---|
| Number of patients 367 Number of observations 693 | Number of patients 487 Number of observations 818 | Number of patients 371 Number of observations 704 | Number of patients 487 Number of observation 830 | |||||
| Estimate | F, P value | Estimate | F, P value | Estimate | F, P value | Estimate | F, P value | |
| SSI-somatic score at baseline | −3.69 | 22, <0.0001 | – | – | −0.088 | 24, <0.0001 | −5.81 | 26, <0.0001 |
| Occupational status (2 df, reference: working for pay) | Other −4.12 | 11, <0.0001 | Other −3.24 | 15, <0.0001 | Other NS | 12, <0.0001 | Other −6.92 | 20, <0.0001 |
| Unemployed −6.43 | Unemployed −3.62 | Unemployed −0.165 | Unemployed −12.54 | |||||
| Baseline score for the dependent variable | 0.22 | 10, 0.002 | 0.6 | 452, <0.0001 | 0.228 | 22, <0.0001 | 0.25 | 34, <0.0001 |
| HADS-D at baseline | −0.51 | 9, 0.004 | – | – | −0.009 | 8, 0.004 | −0.53 | 6, 0.016 |
| Switch within or between antidepressants class (2 df) (reference: no switch) | Between NS | 5, 0.006 | – | – | Between NS | 5, 0.007 | – | – |
| Within −7.13 | – | – | Within −0.144 | – | – | |||
| Any psychiatric illnesses in 24 months before baseline (reference: none) | −3.13 | 7, 0.009 | – | – | – | – | – | – |
| Gender (reference: male) | Female 2.70 | 5, 0.022 | – | – | Female 0.063 | 7, 0.008 | Female 3.28 | 4, 0.040 |
| Age at first episode | 0.09 | 5, 0.028 | – | – | 0.003 | 5, 0.025 | – | – |
| Age | – | – | −0.09 | 17, <0.0001 | –0.005 | 11, <0.001 | – | – |
| Any functional syndrome (reference: none) | – | – | −2.05 | 7, 0.007 | – | – | – | – |
| Marital status (reference: other) | – | – | Married/domestic partner −1.86 | 9, 0.003 | – | – | – | – |
| Number of previous episodes of depression | – | – | – | – | – | – | −3.28 | 9, 0.003 |
| Duration of current episode of depression | – | – | – | – | – | – | −0.11 | 6, 0.017 |
Estimates represent the change in the dependent variable associated with a difference of 1 unit (or 1 category for categorical variables) in the independent variable. Greater F values and smaller p values give an indication of the relative strength of association of the independent variables with the HRQoL outcome. A dash in the column means the variable was nonsignificant. Other independent variables included in the regression analysis but not significant in any of the HRQoL outcome models were: education (none/mandatory, further), body mass index, number of dependants, smoking (yes, no), HADS-A score, and pain cohort (no/mild pain, explained pain, unexplained pain)
df degrees of freedom, EQ-5D European Quality of Life-5 Dimensions, HADS-A Hospital Anxiety and Depression Scale-anxiety score, HADS-D Hospital Anxiety and Depression Scale-depression score, HRQoL health-related quality of life, MCS mental component summary, NS not significant, PCS physical component summary, SF-36 Short Form 36 Health Status Survey, SSI somatic symptom inventory relates to 21 nonpain somatic items only, VAS visual analog scale