Dose Escalation of Antidepressants in Unipolar Depression: A Meta-Analysis of Double-Blind, Randomized Controlled Trials

Dose-response effects of selective serotonin reuptake inhibitor monotherapy for the treatment of depression: systematic review of reviews and meta-narrative synthesis

Objective

To assess and clarify the relations between selective serotonin reuptake inhibitor (SSRI) dose efficacy, acceptability (early treatment discontinuation (dropouts)), and tolerability (reported adverse drug effects), and critically evaluate methods previously used to examine SSRI dose-response effects for the treatment of depression in adults.

Design

Systematic review of reviews and meta-narrative synthesis.

Data sources

Embase, Medline, PsycINFO, Scopus, and the Cochrane Collaboration library, from 1975 to December 2021. Reference lists of national depression treatment guidelines were systemically searched by hand.

Eligibility criteria for selecting studies

Reviews assessing SSRI monotherapy dose-response effects for the treatment of depression in adults (age ≥18 years) reporting efficacy, acceptability, or tolerability. Reviews meeting inclusion criteria had a high degree of heterogeneity, due to methodological diversity; therefore, a meta-narrative synthesis approach was applied. Standard daily doses were defined as 20 mg citalopram, fluoxetine, paroxetine; 50 mg sertraline; and 10 mg escitalopram. Risk of bias was assessed using the Risk of Bias in Systematic Reviews tool, in line with Cochrane recommendations.

Results

The search identified 9138 records; 387 full text reports were assessed for eligibility, 42 of which matched the inclusion criteria. The majority, 83% (n=35), of reviews included data for studies with a duration of ≤12 weeks (ie, the acute phase of depression treatment). Of 39 reviews assessing efficacy, the majority (n=26) indicated that individual SSRIs and SSRI class demonstrated flat dose-response effects; standard doses were optimal for efficacy. Acceptability or tolerability were assessed in 28 reviews. Higher than standard daily doses were associated with higher dropout rates and a greater incidence of adverse drug effects (eg, nausea, sexual dysfunction, fatigue, anxiety). Despite a range of methods being reported, there was an overall consensus regarding SSRI dose related efficacy, dropouts, and adverse drug effects.

Conclusion

Standard daily doses of SSRIs for the treatment of depression in adults provide a favourable balance between efficacy, acceptability, and tolerability. Patients are encouraged to talk to their prescriber or community pharmacist if they experience adverse effects or have any concerns about their drug treatments.

Dose-Response Relationship in Selective Serotonin and Norepinephrine Reuptake Inhibitors in the Treatment of Major Depressive Disorder: A Meta-Analysis and Network Meta-Analysis of Randomized Controlled Trials

INTRODUCTION

Selective serotonin and norepinephrine reuptake inhibitors (SNRI) are among the most prescribed antidepressants, and dose escalation is a frequently applied strategy after non-response to an initially prescribed dose.

OBJECTIVE

This meta-analysis aimed to find evidence of a dose-response relationship or to the contrary in direct comparisons of different SNRI doses in patients with major depressive disorder.

METHODS

A systematic literature search for RCTs comparing at least two doses of SNRIs was carried out in CENTRAL, PubMed, PsycINFO, and EMBASE. Doses were classified as high, medium, and low according to manufacturers' product monographs and analyses at the level of SNRIs as a group and for single substances, accompanied by sensitivity network meta-analyses (Prospero CRD42018081031).

RESULTS

From 2,070 studies screened, we included 26 studies with a total of 10,242 patients. Comparisons of medium versus low and high versus medium doses resulted in clinically and statistically non-significant standardized mean differences of -0.06 (-0.16 to 0.04) and -0.06 (-0.16 to 0.03) in favor of higher doses. In the analyses of single substances, no statistically significant results emerged, and many contrasts yielded very small effect sizes. Dropouts due to side effects tended to be more frequent with higher doses. Heterogeneity was low. Network meta-analyses of direct comparisons supported the findings, as did a risk of bias analysis.

CONCLUSION

Based on the lack of positive evidence for a dose-response relationship in SNRIs as a group and in single SNRIs, we recommend prescribing medium doses. In case of insufficient response, we do not recommend increasing the dose of SNRIs.

Evidence on sociodemographic and clinical correlates of antidepressant combination or augmentation with second-generation antipsychotics in major depressive disorder

About two thirds of the patients with major depressive disorder (MDD) do not sufficiently respond to monotherapy with antidepressants (ADs) which makes them reliant on further treatment approaches. Hereby, combination of different ADs and augmentation with second-generation antipsychotics (SGAs) are widely used and recommended psychopharmacotherapeutic strategies. The present secondary analyses are based on an international, naturalistic, cross-sectional multicenter study conducted by the European Group for the Study of Resistant Depression. Comparing socio-demographic and clinical characteristics of 436 adult MDD patients receiving either SGAs (N = 191, 43.8%) or ADs (N = 245, 56.2%), that were additionally administered to their first-line AD psychopharmacotherapy, we aimed to identify possible trajectories of decision-making for clinicians regarding which treatment option to prefer in individual patients. Our most robust findings represent an association of SGA augmentation with the presence of psychotic symptoms, longer mean duration of lifetime psychiatric hospitalizations, employment of further augmentation strategies with mood-stabilizers and benzodiazepines, and a trend towards higher mean daily dosages of their first-line ADs and current suicidal risk. Treatment outcome was not significantly different between patients receiving either SGA augmentation or AD combination. Being aware of limitations inherent to the cross-sectional study design and the lack of randomization, more severe and rather chronic conditions in MDD seemed to encourage clinicians to choose SGA augmentation over AD combination. The fact that mood-stabilizers and/or benzodiazepines were more frequently co-administered with SGAs may represent a requirement of an overall refined psychopharmacotherapy including additional fast-acting agents with potent AD, tranquilizing and anti-suicidal effects in MDD patients experiencing challenging clinical manifestations. New glutamatergic substances seem to be promising in this regard.

Pregabalin augmentation of antidepressants in major depression - results from a European multicenter study

BACKGROUND

We aimed to investigate the prescription pattern of pregabalin augmentation of antidepressants in major depressive disorder (MDD) and to explore variables associated with add-on pregabalin treatment.

METHODS

1410 MDD patients participated in this naturalistic European multicenter study with retrospective assessment of treatment response. Analyses of covariance, chi-squared tests, and binary logistic regressions were accomplished to determine differences in socio-demographic and clinical characteristics between MDD patients with and without pregabalin augmentation.

RESULTS

Add-on pregabalin was established in 102 (7.23%) MDD patients. Compared to those without receiving pregabalin, pregabalin-treated patients were characterized by a significantly higher likelihood for older age (mean: 54.74 ± 13.08 vs 49.93 ± 14.13 years), unemployment (78.43% vs 51.23%), melancholic features (83.33% vs 58.94%), inpatient treatment (72.55% vs 31.65%), previous psychiatric hospitalizations (13.52 ± 24.82 vs 4.96 ± 19.93 weeks), any somatic comorbidity (68.63% vs 44.57%), comorbid hypertension (37.25% vs 17.51%), more severe depressive symptom severity at the onset of the current episode (mean MADRS: 37.55 ± 9.00 vs 33.79 ± 7.52), receiving augmentation/combination treatment strategies in general (mean number of psychotropic drugs: 3.64 ± 0.92 vs 2.07 ± 1.17), and with antidepressants (50.00% vs 27.91%) and antipsychotics (46.08% vs 24.08%) in particular.

LIMITATIONS

Due to its observational cross-sectional study design, our patient sample might not be fully representative for MDD patients in primary care settings.

CONCLUSIONS

Our findings suggest that add-on pregabalin is particularly administered in more severe/difficult-to-treat MDD conditions, whereas no association between the prescription of adjunctive pregabalin and comorbid anxiety symptoms could be determined.

Sex-related effects in major depressive disorder: Results of the European Group for the Study of Resistant Depression

BACKGROUND

Sex-related effects on the evolution and phenotype of major depressive disorder (MDD) were reported previously.

METHODS

This European multicenter cross-sectional study compared sociodemographic, clinical, and treatment patterns between males and females in a real-world sample of 1410 in- and outpatients with current MDD.

RESULTS

Male MDD patients (33.1%) were rather inpatients, suffered from moderate to high suicidality levels, received noradrenergic and specific serotonergic antidepressants (ADs) as first-line AD treatment, generally higher mean AD daily doses, and showed a trend towards a more frequent administration of add-on treatments. Female MDD patients (66.9%) were rather outpatients, experienced lower suicidality levels, comorbid thyroid dysfunction, migraine, asthma, and a trend towards earlier disease onset.

CONCLUSIONS

The identified divergencies may contribute to the concept of male and female depressive syndromes and serve as predictors of disease severity and course, as they reflect phenomena that were repeatedly related to treatment-resistant depression (TRD). Especially the greater necessity of inpatient treatment and more complex psychopharmacotherapy in men may reflect increased therapeutic efforts undertaken to treat suicidality and to avoid TRD. Hence, considering sex may guide the diagnostic and treatment processes towards targeting challenging clinical manifestations including comorbidities and suicidality, and prevention of TRD and chronicity.

Combining psychopharmacotherapy and psychotherapy is not associated with better treatment outcome in major depressive disorder - evidence from the European Group for the Study of Resistant Depression

Despite plenty of effective antidepressant (AD) treatments, the outcome of major depressive disorder (MDD) is often unsatisfactory, probably due to improvable exploitation of available therapies. This European, cross-sectional, naturalistic multicenter study investigated the frequency of additional psychotherapy in terms of a manual-driven psychotherapy (MDP) in 1410 adult in- and outpatients with MDD, who were primarily treated with AD psychopharmacotherapy. Socio-demographic and clinical patterns were compared between patients receiving both treatments and those lacking concomitant MDP. In a total of 1279 MDD patients (90.7%) with known status of additional MDP, those undergoing a psychopharmacotherapy-MDP combination (31.2%) were younger, higher educated, more often employed and less severely ill with lower odds for suicidality as compared to patients receiving exclusively psychopharmacotherapy (68.8%). They experienced an earlier mean age of MDD onset, melancholic features, comorbid asthma and migraine and received lower daily doses of their first-line ADs. While agomelatine was more often established in these patients, MDD patients without MDP received selective serotonin reuptake inhibitors more frequently. These two patient groups did not differ in terms of response, non-response and treatment resistant depression (TRD). Accordingly, the employment of additional MDP could not be related to better treatment outcomes in MDD. The fact that MDP was applied in a minority of patients with rather beneficial socio-demographic and clinical characteristics might reflect inferior accessibility of these psychotherapeutic techniques for socially and economically disadvantaged populations.

Neglected but not negligible aspects of antidepressants and their availability in bipolar depression

OBJECTIVES

Although many antidepressants are available, they are not always used appropriately. For appropriate use of antidepressants, the old concept of a linear dose-response relationship, in which the dose is linearly increased to achieve a sufficient antidepressant effect, should be reconsidered. Furthermore, there is ongoing debate on the safe and appropriate use of antidepressants in patients with bipolar depression. Antidepressants may be used under certain conditions in patients with bipolar depression. These neglected-but not negligible-aspects of antidepressants have been discussed herein.

METHODS

A narrative qualitative review RESULTS: Dose-response relationships of antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are not linear. They may be bell-shaped, with efficacy initially increasing with an increase in dose but decreasing when the dose is increased beyond a certain point. Despite using international diagnostic criteria, uncertainty remains on whether operationally diagnosed depression is latent bipolar I depression, latent bipolar II depression, or true depression. Furthermore, operationally diagnosed bipolar II depression may be latent bipolar I depression, true bipolar II depression, or depression with false hypomanic episodes. Manic/hypomanic switches are most likely to occur in patients receiving tricyclic antidepressants, followed by those receiving serotonin and noradrenaline reuptake inhibitors and SSRIs, in that order. Also, these switches are most likely to occur in patients with bipolar I depression, followed by those with bipolar II depression and true depression, in that order.

CONCLUSIONS

Considering the diagnostic subtype of bipolar depression and antidepressant properties may help to determine the optimal treatment strategy.

Exploring the metabolic characteristics and pharmacokinetic variation of paroxetine in healthy volunteers using a pharmacometabonomic approach

The pharmacokinetic parameters of paroxetine vary between individuals, leading to differences in efficacy. The focus of our research was to predict responses to paroxetine using a pharmacometabonomic approach combining metabolic phenotypes and pharmacokinetic parameters. The pharmacokinetics of 12 healthy volunteers treated with paroxetine over two cycles was determined using high-performance liquid chromatography tandem mass spectrometry. Metabolic profiling and phenotyping were performed on the blood samples that remained after pharmacokinetic studies, using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry. Thirty-nine metabolites (p < 0.05) increased or decreased after treatment with paroxetine. Vitamin B6 metabolism; valine, leucine, and isoleucine biosynthesis; phenylalanine metabolism; pantothenate and coenzyme A biosynthesis; tyrosine metabolism; and glyoxylate and dicarboxylate metabolism were likely to be relevant for the effects of paroxetine. The two-stage partial least squares (PLS) strategy was used to screen potential biomarkers and predict the pharmacokinetic parameters of paroxetine. An orthogonal PLS discriminant analysis strategy was then applied to separate the high- and low-value groups based on the screened biomarkers. Pearson correlation test and receiver operating characteristic curve analysis confirmed the key prediction biomarkers. Seven common biomarkers were able to predict both the area under the curve (AUC) and the maximum concentration (C_max): cortisone, l-tyrosine, phenylpyruvate, l-valine, 2-oxoglutarate, l-lactate, and glycerate. Furthermore, homoprotocatechuate and l-glutamate were unique biomarkers for AUC, and citicoline and fumarate were unique biomarkers for C_max. The selected biomarkers were able to predict the AUC and C_max and discriminate good responders from poor responders to paroxetine treatment. This trial was registered with http://www.chinadrugtrials.org.cn/ (no. CTR20171590).

In search of a dose-response relationship in SSRIs-a systematic review, meta-analysis, and network meta-analysis

OBJECTIVE

Recent meta-analyses on dose-response relationships of SSRIs are largely based on indirect evidence. We analyzed RCTs directly comparing different SSRI doses.

METHOD

Systematic literature search for RCTs. Two raters independently screened articles and extracted data. Across SSRIs, doses defined as low, medium, and high doses, based on drug manufacturers' product monographs, were analyzed in pairwise random-effects meta-analyses and in a sensitivity network meta-analysis with regard to differences in antidepressive efficacy (primary outcome). We also analyzed all direct comparisons of different dosages of specific SSRIs. (Prospero CRD42018081031).

RESULTS

Out of 5333 articles screened, we included 33. Comparisons of dosage groups (low, medium, and high) resulted in only small and clinically non-significant differences for SSRIs as a group, the strongest relating to medium vs low doses (SMD: -0.15 [95%-CI: -0.28; -0.01) and not sustained in a sensitivity analysis. Among different doses of specific SSRIs, no statistically significant trend emerged for efficacy at higher doses, but 60 mg/day fluoxetine are statistically significantly inferior to 20 mg/day. Paroxetine results are inconclusive: 10 mg/day are inferior to higher doses, but 30 and 40 mg/day are inferior to 20 mg/day. Meaningful effects cannot be ruled out for certain drugs and dosages, often investigated in only one trial. Dropout rates increase with dose-particularly due to side effects. Network meta-analyses supported our findings.

CONCLUSIONS

There is no conclusive level I or level II evidence of a clinically meaningful dose-response relationship of SSRIs as a group or of single substances. High SSRI doses are not recommended as routine treatment.

Relapse prevention in recurrent major depressive disorder. A comparison of different treatment options based on clinical experience and a critical review of the literature

BACKGROUND

Reducing the risk of relapses is a critical component of major depressive disorders treatment. Guidelines suggest maintenance with antidepressant drugs in recurrent depression, but this solution has recently been questioned.

OBJECTIVE

The aim of this article is to provide a critical review of the literature of the main treatment options currently available to prevent relapse and recurrence in depression.

METHODS

We compared long-term antidepressant therapy (i.e., indefinite maintenance of antidepressant), intermittent antidepressant therapy (i.e., use of antidepressants mainly limited to the acute phases), use of psychotherapy in the sequential model (i.e., pharmacotherapy in the acute phase and psychotherapy in the residual phase).

RESULTS

We argue that the same solution may not apply to all patients and question the feasibility of a single course of treatment in the setting of complex disorders that are encountered in practice. The clinician should weigh advantages and disadvantages in the individual case.

CONCLUSIONS

The sequential model appears to be particularly indicated in recurrent depression. KEY POINTS Relapse is a major challenge of depressive disorders treatment Treatment options currently available include long-term antidepressants, intermittent antidepressants, addition of psychotherapy to pharmacotherapy in the sequential model Maintenance with antidepressants in recurrent depression has recently been questioned The sequential model appears to be particularly indicated in recurrent depression.

Pretreatment Reward Sensitivity and Frontostriatal Resting-State Functional Connectivity Are Associated With Response to Bupropion After Sertraline Nonresponse

BACKGROUND

Standard guidelines recommend selective serotonin reuptake inhibitors as first-line antidepressants for adults with major depressive disorder, but success is limited and patients who fail to benefit are often switched to non-selective serotonin reuptake inhibitor agents. This study investigated whether brain- and behavior-based markers of reward processing might be associated with response to bupropion after sertraline nonresponse.

METHODS

In a two-stage, double-blinded clinical trial, 296 participants were randomized to receive 8 weeks of sertraline or placebo in stage 1. Individuals who responded continued on another 8-week course of the same intervention in stage 2, while sertraline and placebo nonresponders crossed over to bupropion and sertraline, respectively. Data from 241 participants were analyzed. The stage 2 sample comprised 87 patients with major depressive disorder who switched medication and 38 healthy control subjects. A total of 116 participants with major depressive disorder treated with sertraline in stage 1 served as an independent replication sample. The probabilistic reward task and resting-state functional magnetic resonance imaging were administered at baseline.

RESULTS

Greater pretreatment reward sensitivity and higher resting-state functional connectivity between bilateral nucleus accumbens and rostral anterior cingulate cortex were associated with positive response to bupropion but not sertraline. Null findings for sertraline were replicated in the stage 1 sample.

CONCLUSIONS

Pretreatment reward sensitivity and frontostriatal connectivity may identify patients likely to benefit from bupropion following selective serotonin reuptake inhibitor failures. Results call for a prospective replication based on these biomarkers to advance clinical care.

A register-based approach to identifying treatment-resistant depression-Comparison with clinical definitions

BACKGROUND

Several definitions of treatment-resistant depression (TRD) are used for clinical research, but no verified model for use in register data exists. We aimed to compare a novel model created for use in register data-the Karolinska Institutet Model (KIM)-to the clinical definitions regarding the proportion of patients identified with TRD, their characteristics and clinical outcomes.

METHODS

All patients in Sweden initiating antidepressant treatment with a diagnosis of depression in specialized healthcare 2006-2014 were identified and followed in national registers. In KIM, patients who initiated a third sequential, >28-day antidepressant treatment trial were defined as having TRD. Proportion of TRD and patient characteristics were compared with register adaptations of the European Staging Model (ESM), Massachusetts General Hospital Staging Method (MGH-s), and Maudsley Staging Model (MSM). Differences in patient characteristics were assessed with Chi-square tests and one-way ANOVAs. Hazard ratios for psychiatric hospitalization and for death from external causes were estimated by Cox proportional hazard regressions.

RESULTS

Out of 127,108 antidepressant initiators with depression, the highest proportion of TRD was found using the MGH-s (19.0%), followed by MSM (15.3%), KIM (12.9%), and ESM (9.5%). Clinical characteristics were similar across the models. Compared with TRD patients identified by KIM, those identified by ESM had a marginally higher risk for psychiatric hospitalization (adjusted hazard ratio [aHR] 1.03, 95%CI 1.00-1.05), whereas those identified by MGH-s (aHR 0.92; 0.90-0.94) and MSM (aHR 0.95; 0.94-0.97) had a slightly reduced risk. Patients identified by MGH-s showed a reduced mortality compared with KIM (aHR 0.84; 0.72-0.98).

CONCLUSIONS

This study provides insight into the differing characteristics of patients captured by various TRD models when used for register research. Models yielding lower proportions of TRD seemed to identify patients with greater morbidity. The KIM may be useful for register based research in TRD.

No benefit from flexible titration above minimum licensed dose in prescribing antidepressants for major depression: systematic review

BACKGROUND

In fixed-dose antidepressant trials, the lower range of the licensed dose achieves the optimal balance between efficacy and tolerability. Whether flexible upward titration while side-effects permit provides additional benefits is unknown.

METHODS

We did a systematic review of placebo-controlled randomized trials that examined selective serotonin reuptake inhibitors (SSRIs), venlafaxine or mirtazapine in the acute treatment of major depression. Our primary outcome was response, defined as 50% or greater reduction in depression severity. Secondary outcomes included drop-outs due to adverse effects and drop-outs for any reason. We conducted random-effects meta-analyses to calculate the ratios of odds ratios (RORs) between trials comparing the flexible dose titrating above the minimum licensed dose against placebo and those comparing the fixed minimum licensed dose against placebo.

RESULTS

We included 123 published and unpublished randomized controlled trials (29 420 participants). There was no evidence supporting efficacy of the flexible dosing over the fixed low dose of SSRIs (ROR 0.96, 95% CI: 0.73 to 1.25), venlafaxine (1.24, 0.96 to 1.60) or mirtazapine (0.77, 0.33 to 1.78). No important differences were noted for tolerability or for any subgroup analyses except the superior efficacy of venlafaxine flexible dosing between 75 and 150 mg over the fixed 75 mg (1.30, 1.02 to 1.65).

CONCLUSION

There was no evidence to support added value in terms of efficacy, tolerability or acceptability of flexibly titrating up the dosage over the minimum licensed dose of SSRIs or mirtazapine. For venlafaxine, increased efficacy can be expected by flexibly titrating up to 150 mg.

Results of the European Group for the Study of Resistant Depression (GSRD) - basis for further research and clinical practice

Objectives: The overview outlines two decades of research from the European Group for the Study of Resistant Depression (GSRD) that fundamentally impacted evidence-based algorithms for diagnostics and psychopharmacotherapy of treatment-resistant depression (TRD). Methods: The GSRD staging model characterising response, non-response and resistance to antidepressant (AD) treatment was applied to 2762 patients in eight European countries. Results: In case of non-response, dose escalation and switching between different AD classes did not show superiority over continuation of original AD treatment. Predictors for TRD were symptom severity, duration of the current major depressive episode (MDE), suicidality, psychotic and melancholic features, comorbid anxiety and personality disorders, add-on treatment, non-response to the first AD, adverse effects, high occupational level, recurrent disease course, previous hospitalisations, positive family history of MDD, early age of onset and novel associations of single nucleoid polymorphisms (SNPs) within the PPP3CC, ST8SIA2, CHL1, GAP43 and ITGB3 genes and gene pathways associated with neuroplasticity, intracellular signalling and chromatin silencing. A prediction model reaching accuracy of above 0.7 highlighted symptom severity, suicidality, comorbid anxiety and lifetime MDEs as the most informative predictors for TRD. Applying machine-learning algorithms, a signature of three SNPs of the BDNF, PPP3CC and HTR2A genes and lacking melancholia predicted treatment response. Conclusions: The GSRD findings offer a unique and balanced perspective on TRD representing foundation for further research elaborating on specific clinical and genetic hypotheses and treatment strategies within appropriate study-designs, especially interaction-based models and randomized controlled trials.

Duloxetine plasma level and antidepressant response

BACKGROUND

Major Depressive Disorder (MDD) is associated with a high rate of inadequate treatment response, which is mainly due to the large inter-individual genetic variability in pharmacokinetic and pharmacodynamic targets of antidepressant drugs. Little is still known about the exact association between plasma level of first-line antidepressants and clinical response. This is particularly true for duloxetine, a dual serotonin and norepinephrine reuptake inhibitor recommended as first-line treatment for MDD. The aim of this study was to investigate the association between serum concentration of duloxetine (SCD) and antidepressant response (AR).

METHODS

66 MDD patients treated with duloxetine 60 mg/day monotherapy were recruited in an outpatient setting and followed for three months. Hamilton Depression Rating Scale - 21 (HAMD-21) was administrated at baseline, at month 1, and at month 3 to assess AR. SCD was measured at steady state. Linear regression analysis and nonlinear least-squares regression were used to estimate association between SCD and AR.

RESULTS

SCD showed a high inter-individual variability in our sample, despite the duloxetine fixed oral dosage. We found a strong association between SCD and AR following a bell-shaped function at month 1 and at month 3. Nonetheless, within the recommended SCD range of 30-120 ng/mL a more linear correlation between SCD and AR was observed.

DISCUSSION

Our results suggest that for duloxetine the association between SCD and AR likely follows a bell-shaped quadratic function with poor AR at subtherapeutic SCD and progressive decrease of AR at higher SCD. The maximum antidepressant efficacy seems to require SCD values next to the highest recommended SCD (30-120 ng/mL), probably because of the optimal saturation of both serotonin and norepinephrine transporters. Thus, taking into account the observed high interindividual variability of SCD, our findings suggest that for MDD patients treated with duloxetine, SCD could be a useful tool to guide the treatment by optimizing the oral dosage in order to increase the AR rate.

International Union of Basic and Clinical Pharmacology CIV: The Neurobiology of Treatment-resistant Depression: From Antidepressant Classifications to Novel Pharmacological Targets

Major depressive disorder is one of the most prevalent and life-threatening forms of mental illnesses and a major cause of morbidity worldwide. Currently available antidepressants are effective for most patients, although around 30% are considered treatment resistant (TRD), a condition that is associated with a significant impairment of cognitive function and poor quality of life. In this respect, the identification of the molecular mechanisms contributing to TRD represents an essential step for the design of novel and more efficacious drugs able to modify the clinical course of this disorder and increase remission rates in clinical practice. New insights into the neurobiology of TRD have shed light on the role of a number of different mechanisms, including the glutamatergic system, immune/inflammatory systems, neurotrophin function, and epigenetics. Advances in drug discovery processes in TRD have also influenced the classification of antidepressant drugs and novel classifications are available, such as the neuroscience-based nomenclature that can incorporate such advances in drug development for TRD. This review aims to provide an up-to-date description of key mechanisms in TRD and describe current therapeutic strategies for TRD before examining novel approaches that may ultimately address important neurobiological mechanisms not targeted by currently available antidepressants. All in all, we suggest that drug targeting different neurobiological systems should be able to restore normal function but must also promote resilience to reduce the long-term vulnerability to recurrent depressive episodes.

Depression

Major depression is a common illness that severely limits psychosocial functioning and diminishes quality of life. In 2008, WHO ranked major depression as the third cause of burden of disease worldwide and projected that the disease will rank first by 2030.¹ In practice, its detection, diagnosis, and management often pose challenges for clinicians because of its various presentations, unpredictable course and prognosis, and variable response to treatment.

Optimising first- and second-line treatment strategies for untreated major depressive disorder - the SUN☺D study: a pragmatic, multi-centre, assessor-blinded randomised controlled trial

BACKGROUND

For patients starting treatment for depression, current guidelines recommend titrating the antidepressant dosage to the maximum of the licenced range if tolerated. When patients do not achieve remission within several weeks, recommendations include adding or switching to another antidepressant. However, the relative merits of these guideline strategies remain unestablished.

METHODS

This multi-centre, open-label, assessor-blinded, pragmatic trial involved two steps. Step 1 used open-cluster randomisation, allocating clinics into those titrating sertraline up to 50 mg/day or 100 mg/day by week 3. Step 2 used central randomisation to allocate patients who did not remit after 3 weeks of treatment to continue sertraline, to add mirtazapine or to switch to mirtazapine. The primary outcome was depression severity measured with the Patient Health Questionnaire-9 (PHQ-9) (scores between 0 and 27; higher scores, greater depression) at week 9. We applied mixed-model repeated-measures analysis adjusted for key baseline covariates.

RESULTS

Between December 2010 and March 2015, we recruited 2011 participants with hitherto untreated major depression at 48 clinics in Japan. In step 1, 970 participants were allocated to the 50 mg/day and 1041 to the 100 mg/day arms; 1927 (95.8%) provided primary outcomes. There was no statistically significant difference in the adjusted PHQ-9 score at week 9 between the 50 mg/day arm and the 100 mg/day arm (0.25 point, 95% confidence interval (CI), - 0.58 to 1.07, P = 0.55). Other outcomes proved similar in the two groups. In step 2, 1646 participants not remitted by week 3 were randomised to continue sertraline (n = 551), to add mirtazapine (n = 537) or to switch to mirtazapine (n = 558): 1613 (98.0%) provided primary outcomes. At week 9, adding mirtazapine achieved a reduction in PHQ-9 scores of 0.99 point (0.43 to 1.55, P = 0.0012); switching achieved a reduction of 1.01 points (0.46 to 1.56, P = 0.0012), both relative to continuing sertraline. Combination increased the percentage of remission by 12.4% (6.1 to 19.0%) and switching by 8.4% (2.5 to 14.8%). There were no differences in adverse effects.

CONCLUSIONS

In patients with new onset depression, we found no advantage of titrating sertraline to 100 mg vs 50 mg. Patients unremitted by week 3 gained a small benefit in reduction of depressive symptoms at week 9 by switching sertraline to mirtazapine or by adding mirtazapine.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01109693 . Registered on 23 April 2010.

Predicting antidepressant response by monitoring early improvement of individual symptoms of depression: individual patient data meta-analysis

BACKGROUND

Improvement in depression within the first 2 weeks of antidepressant treatment predicts good outcomes, but non-improvers can still respond or remit, whereas improvers often do not.AimsWe aimed to investigate whether early improvement of individual depressive symptoms better predicts response or remission.

METHOD

We obtained individual patient data of 30 trials comprising 2184 placebo-treated and 6058 antidepressant-treated participants. Primary outcome was week 6 response; secondary outcomes were week 6 remission and week 12 response and remission. We compared models that only included improvement in total score by week 2 (total improvement model) with models that also included improvement in individual symptoms.

RESULTS

For week 6 response, the area under the receiver operating characteristic curve and negative and positive predictive values of the total improvement model were 0.73, 0.67 and 0.74 compared with 0.77, 0.70 and 0.71 for the item improvement model. Model performance decreased for week 12 outcomes. Of predicted non-responders, 29% actually did respond by week 6 and 43% by week 12, which was decreased from the baseline (overall) probabilities of 51% by week 6 and 69% by week 12. In post hoc analyses with continuous rather than dichotomous early improvement, including individual items did not enhance model performance.

CONCLUSIONS

Examining individual symptoms adds little to the predictive ability of early improvement. Additionally, early non-improvement does not rule out response or remission, particularly after 12 rather than 6 weeks. Therefore, our findings suggest that routinely adapting pharmacological treatment because of limited early improvement would often be premature.Declaration of interestNone.

Clinical correlates of augmentation/combination treatment strategies in major depressive disorder

OBJECTIVE

This multicenter, multinational, cross-sectional study aimed to investigate clinical characteristics and treatment outcomes associated with augmentation/combination treatment strategies in major depressive disorder (MDD).

METHOD

Sociodemographic, clinical, and treatment features of 1410 adult MDD patients were compared between MDD patients treated with monotherapy and augmentation/combination medication using descriptive statistics, analyses of covariance (ancova), and Spearman's correlation analyses.

RESULTS

60.64% of all participants received augmentation and/or combination strategies with a mean number of 2.18 ± 1.22 simultaneously prescribed psychiatric drugs. We found male gender, older age, Caucasian descent, higher weight, low educational status, absence of occupation, psychotic symptoms, melancholic and atypical features, suicide risk, in-patient treatment, longer duration of hospitalization, some psychiatric comorbidities (panic disorder, agoraphobia, obsessive-compulsive disorder, and bulimia nervosa), comorbid somatic comorbidity in general and concurrent hypertension, thyroid dysfunction, diabetes, and heart disease in particular, higher current and retrospective Montgomery and Åsberg Depression Rating Scale total scores, treatment resistance, and higher antidepressant dosing to be significantly associated with augmentation/combination treatment. These findings were corroborated when examining the number of concurrently administered psychiatric drugs in the statistical analyses.

CONCLUSION

Our findings suggest a clear association between augmentation/combination strategies and treatment-resistant/difficult-to-treat MDD conditions characterized by severe symptomatology and high amount of psychiatric and somatic comorbidities.

Low comorbid obsessive-compulsive disorder in patients with major depressive disorder - Findings from a European multicenter study

BACKGROUND

This cross-sectional European multicenter study examined the association between major depressive disorder (MDD) and comorbid obsessive-compulsive disorder (OCD).

METHODS

Socio-demographic, clinical, and treatment features of 1346 adult MDD patients were compared between MDD subjects with and without concurrent OCD using descriptive statistics, analyses of covariance (ANCOVA), and binary logistic regression analyses.

RESULTS

We determined a point prevalence of comorbid OCD in MDD of 1.65%. In comparison to the MDD control group without concurrent OCD, a higher proportion of patients in the MDD + comorbid OCD group displayed concurrent panic disorder (31.81% vs 7.77%, p<.001), suicide risk (52.80% vs 44.81%, p=.04), polypsychopharmacy (95.45% vs 60.21%, p=.001), and augmentation treatment with antipsychotics (50.00% vs 25.46%, p=.01) and benzodiazepines (68.18% vs 33.31%, p=.001). Moreover, they were treated with higher mean doses of their antidepressant drugs (in fluoxetine equivalents: 48.99mg/day ± 18.81 vs 39.68mg/day ± 20.75, p=.04). In the logistic regression analyses, comorbid panic disorder (odds ratio (OR)=4.17, p=.01), suicide risk (OR=2.56, p=.04), simultaneous treatment with more psychiatric drugs (OR=1.51, p=<.05), polypsychopharmacy (OR=14.29, p=.01), higher antidepressant dosing (OR=1.01, p=<.05), and augmentation with antipsychotics (OR=2.94, p=.01) and benzodiazepines (OR=4.35, p=.002) were significantly associated with comorbid OCD.

CONCLUSION

In summary, our findings suggest that concurrent OCD in MDD (1) has a low prevalence rate compared to the reverse prevalence rates of comorbid MDD in OCD, (2) provokes higher suicide risk, and (3) is associated with a characteristic prescription pattern reflected by a high amount of polypsychopharmaceutical treatment strategies comprising particularly augmentation with antipsychotics and benzodiazepines.