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Department of Psychiatry and Behavioral Sciences, University of Texas Medical Branch at Galveston, 1.302 Rebecca Sealy, 301 University Blvd, Galveston, TX 77555-0188, USA. Tel: +1 409 747 9791; fax: +1 409 747 8300
Correspondence: e-mail: rohirsch{at}utmb.edu
Declaration of interest R.M.A.H. received an honorarium and travel expenses from Eli Lilly & Co.
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ABSTRACT |
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Aims To highlight the clinical importance of long-term antidepressant therapy in the treatment of depression.
Method The current literature was reviewed to examine the relationship between duration of antidepressant therapy and efficacy.
Results Approximately one-third to a half of patients successfully stabilised in acute-phase treatment will relapse if medication is not sustained throughout the continuation period. Only 10-15% will relapse if medication is continued. For maintenance-phase therapy, approximately 60% of patients at risk will experience a recurrent episode of depression within 1 year if untreated, whereas those who continue in treatment will have a recurrence rate of between 10% and 30%.
Conclusions Risk of relapse and recurrence of depression can be significantly reduced if adequate continuation and maintenance therapy durations are achieved.
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INTRODUCTION |
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Research findings emerging in the 1980s challenged this view. For example, the National Institute of Mental Health Collaborative Program of the Psychobiology of Depression involved a multi-year follow-up of over 400 patients. After 15 years, only one in eight of these patients had recovered from their original episode and stayed well (Keller et al, 1992). Over 80% had suffered at least one recurrence, and 6% had remained chronically depressed throughout the entire 15-year period.
These and other findings, as well as experience with antidepressant pharmacotherapy, have led physicians to return to the Kraepelinean notion of depression as a long-term, recurrent and often chronic illness. Treatment for the disorder has both short-term and long-term aspects: short-term treatment includes acute and continuation phases, while long-term treatment consists of the maintenance phase (Kupfer, 1991).
The acute phase involves stabilisation of the acute symptoms and generally lasts up to 3 months (Fig. 1). However, in complicated cases, acute treatment may take considerably longer. The continuation phase begins with stabilisation and ends at the point at which the depression would have ended had there been no successful treatment (often thought to be an additional 6-12 months beyond acute symptom resolution). If depressive symptoms return during the continuation period, it is considered to be a relapse into the original episode of illness. Thus, treatment for a single episode can take over a year, but in most cases will last 6-12 months. The maintenance phase involves prevention of new episodes (recurrences) and can extend for years.
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ACUTE TREATMENT |
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CONTINUATION TREATMENT |
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Six continuation studies of TCAs, primarily amitriptyline, were identified (Table 1). Overall, less than one-fifth of those on active drug therapy relapsed compared with over half of those on placebo.
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Several similarly designed studies of selective serotonin reuptake inhibitors (SSRIs) and other newer agents have also been conducted. For example, in an international, multi-centre study, 467 patients with major depressive disorder were enrolled in an open-label trial of sertraline for 8 weeks (Doogan & Caillard, 1992). Of the 300 responders, 185 agreed to be randomised either to stay on sertraline or to be blindly switched to placebo. After approximately 10 months of follow-up, nearly 13% of patients taking active medication relapsed compared with 46% on placebo (P<0.001) (Doogan & Caillard, 1992). Most of the relapses in this study occurred within the first 6 months of continuation treatment (Fig. 2).
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Additional continuation studies involving paroxetine, nefazodone, citalopram, reboxetine, amineptine and fluoxetine, with nearly identical protocol designs, gave very similar results (Montgomery & Dunbar, 1993; Montgomery et al, 1993; Robert & Montgomery, 1995; Ferreri et al, 1997; Reimherr et al, 1998; Feiger et al, 1999; Versiani et al, 1999). Approximately one-third to one-half of patients who did not continue active treatment after stabilisation (i.e. were switched to placebo) relapsed, whereas about 15% relapsed if they continued on active medication (Table 1).
The continuation study conducted by Reimherr et al was designed to assess not only rates of relapse, but also the question of how long continuation therapy should last. Patients with major depression were treated in an open-label trial with 20 mg per day of fluoxetine for 12 weeks (Reimherr et al, 1998). Patients who had sustained remission during this period were randomised either to continue on fluoxetine or to be blindly switched to placebo. Groups of patients in the fluoxetine arm were then randomised to placebo after a further 14 or 18 weeks (for a total of 26 or 50 weeks of treatment), or were maintained on fluoxetine for the entire 50 weeks of the continuation period (for a total of 62 weeks of treatment) (Fig. 3).
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The results for the patients who were randomised at week 12 to placebo compared with those staying on fluoxetine were consistent with the earlier reported studies. Approximately 20% of those on fluoxetine relapsed, in comparison with nearly half of those on placebo (Fig. 4).
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A second group of patients were blindly discontinued at week 26 from fluoxetine. The rate of relapse for these patients (approximately 21%) was less than that found in patients discontinued at week 12 (approximately 50%), but was still significantly worse than the approximately 5% relapse rate in patients who had remained on fluoxetine throughout the 12-week period. There was no significant difference in relapse between those randomised to placebo at week 50 compared with those who stayed on fluoxetine for an additional 12 weeks (both approximately 12%). These results suggest that continuation therapy should be given for at least 3 months following remission, but in most patients need not be given beyond 9 months following remission.
In summary, results of continuation studies of both older and newer classes of antidepressant consistently demonstrate that approximately one-third to half of all patients will relapse if medication is not sustained throughout the continuation period. Only 10-15% will relapse if medication is continued. The results from the study by Reimherr et al indicate that continuation therapy should last at least 3-9 months following remission.
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MAINTENANCE TREATMENT |
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A number of maintenance therapy studies have been performed using TCAs and one has been performed using an MAOI (Table 2). Although the recurrence rates for active drug versus placebo differ in these studies, the data consistently demonstrate a significantly higher rate of recurrence in patients given placebo compared with those who continue on active drug therapy. While these older classes of antidepressants have proven clinical efficacy, their use in the real world is hampered by concerns about side-effects (including anticholinergic, cardiovascular and histaminic effects), which can lead to non-compliance, as well as the risk of fatal overdose in patients who stockpile medication.
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Maintenance studies involving the SSRIs fluoxetine, fluvoxamine and sertraline have also been performed. In one study, 456 patients with DSMIII (American Psychiatric Association, 1980) recurrent major depression were treated with open-label fluoxetine for 6 weeks (Montgomery et al, 1988). Those who responded were continued on fluoxetine therapy for an additional 18 weeks. Those who completed this 24 weeks of treatment were randomised to continue with fluoxetine (n=88) or to switch blindly to placebo (n=94). Recurrence of depression was defined by a score above 18 on the Hamilton Rating Scale for Depression (Hamilton, 1967). A recurrence rate of 26% occurred in the fluoxetine group during the 1-year follow-up compared with 57% in the placebo group (P<0.001) (Fig. 5).
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A similarly designed study using fluvoxamine gave results consistent with those observed in the fluoxetine study. A mean daily dose of 100 mg of fluvoxamine was shown to be effective in preventing recurrence of DSMIIIR (American Psychiatric Association, 1987) major depressive disorder. Recurrence was defined as a reappearance of depressive symptoms in the opinion of the investigator. The fluvoxamine group had a recurrence rate of 13%, whereas the placebo group had a recurrence rate of 35% (P<0.001) (Terra & Montgomery, 1998).
The studies described above and summarised in Table 2 suggest that, among patients at risk, depression will recur in approximately 60% within 1 year if untreated. If patients continue to receive treatment with newer antidepressants, the recurrence rate drops to between 10% and 30% (Table 2). This clearly supports the efficacy and advisability of maintenance treatment if patients are among those at risk.
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CONCLUSION |
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