A Randomized Controlled Trial of the Tumor Necrosis Factor Antagonist Infliximab for Treatment-Resistant Depression:  The Role of Baseline Inflammatory Biomarkers

Figure 1. Change in scores on the 17-item Hamilton Scale for Depression (HAM-D) for patients with treatment-resistant depression (TRD) randomly assigned to infliximab or placebo. Using a double-blind, placebo-controlled, randomized design, we examined the change in HAM-D scores in an intent-to-treat mixed-effects model for repeated measures analysis of 60 patients with TRD who were administered 3 infusions of the tumor necrosis factor antagonist infliximab (n = 30) or placebo (n = 30) at baseline and at 2 and 6 weeks of a 12-week trial. There was no main effect of treatment assignment and no treatment × time interaction. However, there was a significant effect of time, with both groups exhibiting significant decreases in HAM-D scores across treatment weeks (P = .01). Depicted is the least squares mean change in HAM-D score from baseline to the indicated week using an unstructured covariance matrix with time as a categorical variable. The error bars indicate SEM.

Figure 2. Relationship between change in score on the 17-item Hamilton Scale for Depression (HAM-D) from baseline to week 12 (infliximab minus placebo) and log baseline plasma high-sensitivity C-reactive protein (hs-CRP) concentration in patients with treatment-resistant depression (TRD) who were treated with infliximab or placebo. Based on an interaction between treatment, time, and baseline log hs-CRP concentration (P = .01), the relationship between baseline log plasma hs-CRP concentration and change in HAM-D score from baseline to week 12 (infliximab minus placebo) was examined in 60 patients with TRD who were administered 3 infusions of either the tumor necrosis factor antagonist infliximab (n = 30) or placebo (n = 30) at baseline and at 2 and 6 weeks of a 12-week trial. The solid line represents the adjusted means of the change in HAM-D score from baseline to week 12 (infliximab minus placebo) at each log baseline hs-CRP value based on the mixed-effects model. The dotted lines represent the 95% CIs. At plasma hs-CRP concentrations greater than 4.98 mg/L, the change in HAM-D scores favored infliximab-treated patients, whereas at plasma hs-CRP concentrations below 4.98 mg/L, the change in HAM-D scores favored placebo-treated patients.

Figure 3. Change in score on the 17-item Hamilton Scale for Depression (HAM-D) from baseline to week 12 (infliximab minus placebo) in patients with treatment-resistant depression (TRD) subgrouped by baseline plasma high-sensitivity C-reactive protein (hs-CRP) concentration. To examine the effect of varying concentrations of baseline plasma hs-CRP on the least squares mean change in the HAM-D score from baseline to week 12 (infliximab minus placebo), the sample of patients with TRD were subgrouped into all participants (overall), all participants with a baseline hs-CRP concentration greater than 1 mg/L (n = 45), all participants with a baseline hs-CRP concentration greater than 3 mg/L (n = 27), or all participants with a baseline hs-CRP concentration greater than 5 mg/L (n = 22). When only participants with a hs-CRP concentration greater than 5 mg/L were considered, a 3.1 difference in the HAM-D score favoring infliximab was found between infliximab- and placebo-treated patients. The error bars indicate 95% CI.

Figure 4. Change in score on the 17-item Hamilton Scale for Depression (HAM-D) from baseline to week 12 for infliximab- vs placebo-treated patients with treatment-resistant depression (TRD) who had a baseline high-sensitivity C-reactive protein (hs-CRP) concentration greater than 5 mg/L and in those who had a baseline hs-CRP concentration of 5 mg/L or less. An intent-to-treat mixed-effects model for repeated measures analysis of patients with TRD who were administered the tumor necrosis factor antagonist infliximab or placebo was conducted separately for patients with a baseline hs-CRP concentration greater than 5 mg/L (n = 22) (A) and those with a baseline hs-CRP concentration of 5 mg/L or less (n = 48) (B). In general, opposite effects of infliximab were found depending on baseline hs-CRP concentration. Infliximab was superior to placebo in improving HAM-D scores for participants with a baseline hs-CRP concentration greater than 5 mg/L, but placebo was superior for participants with a baseline hs-CRP concentration of 5 mg/L or less. Although there was a main effect of time on change in HAM-D scores for patients with a baseline hs-CRP concentration greater than 5 mg/L, there were no effects of treatment assignment and no treatment × time interaction. In addition, no main effects of treatment assignment, time, or their interaction were found in participants with a baseline hs-CRP concentration of 5 mg/L or less. Depicted is the least squares mean change in HAM-D score from baseline to the indicated week using an unstructured covariance matrix with time as a categorical variable. The error bars indicate SEM.

Figure 5. Median change in individual items on the 17-item Hamilton Scale for Depression from baseline to week 12 for infliximab- vs placebo-treated patients with treatment-resistant depression (TRD) who had a baseline high-sensitivity C-reactive protein (hs-CRP) concentration greater than 5 mg/L. To determine which symptoms were differentially improved as a function of infliximab treatment, the median change in the 17 items of the Hamilton Scale for Depression was plotted. Infliximab- vs placebo-treated patients with TRD showed greater improvement in symptoms of anxiety (psychic), retardation, work and activities, suicide, and depressed mood from baseline to week 12 if their baseline plasma hs-CRP concentration was greater than 5 mg/L.

Figure 6. Percentage of treatment responders among infliximab- vs placebo-treated patients with treatment-resistant depression (TRD) and a baseline high-sensitivity C-reactive protein (hs-CRP) concentration of 5 mg/L or less or of greater than 5 mg/L. The percentage of treatment responders, which was defined by a 50% or more drop in the 17-item Hamilton Scale for Depression at any time during treatment, was compared between infliximab- and placebo-treated patients with TRD and a baseline plasma hs-CRP concentration of 5 mg/L or less or of greater than 5 mg/L, as well as combined. Infliximab-treated patients exhibited a higher response rate than placebo-treated patients when the hs-CRP concentration was greater than 5 mg/L, but infliximab-treated patients exhibited a lower response rate than placebo-treated patients when the hs-CRP concentration was 5 mg/L or less. These results did not reach statistical significance (P = .19). No difference was found between the groups when combined (P = .99).

Figure 7. Change in plasma high-sensitivity C-reactive protein (hs-CRP) concentrations across treatment and as a function of treatment response in infliximab- vs placebo-treated patients with treatment-resistant depression (TRD). The plasma hs-CRP concentration was measured across the study in all patients with TRD. Infliximab treatment had a significant main effect on plasma hs-CRP concentration (P < .05), leading to significant decreases in hs-CRP concentrations compared with placebo at all time points. Depicted is the least squares mean change in hs-CRP concentration from baseline to the indicated week using an unstructured covariance matrix with time as a categorical variable (A). Comparing placebo responders vs nonresponders, placebo responders had lower hs-CRP concentrations. Infliximab responders exhibited higher baseline hs-CRP concentrations and lower week-12 hs-CRP concentrations than did infliximab nonresponders, but these results also did not reach statistical significance. There was a main effect of treatment on change in hs-CRP concentration from baseline to week 12 (P < .05). Moreover, infliximab responders exhibited a significantly greater decrease in hs-CRP concentrations from baseline to week 12 than did placebo responders (P < .01) (B). The error bars indicate SEM.