Maintenance Phase Efficacy of Sertraline for Chronic Depression: Title and subTitle BreakA Randomized Controlled Trial FREE

AN ACCUMULATING body of research documents the enormous personal, psychosocial, and economic costs of depression. These costs result from reduced capacity to perform normal social roles such as working and parenting.^{1 - 3} Depressed persons also experience diminished quality-of-life dimensions⁴ and may use medical services excessively.⁵ When compared with other medical diseases, the recent World Health Organization Global Burden of Disease study⁶ identified depression as being 1 of the 4 most disabling illnesses in the world. Among the factors contributing to the profound level of disability associated with depression are high prevalence, increased rates of recurrence, chronicity, and associated medical and psychiatric comorbidity.⁷

Epidemiologic surveys confirm that a significant proportion of those diagnosed as having depression (either major or minor) have a chronic course, with lifetime prevalence estimates that are above 5%.^{7 - 8}

Early discontinuation of antidepressant therapy has been associated with a 25% relapse rate within 2 months, even among patients who do not have chronicity.⁹ By 6 months, a 2- to 3-fold difference in relapse rates consistently favors the continuation of pharmacotherapy compared with placebo.^{10 - 12} Thus, continuation of antidepressant therapy (defined as the 4-9 months of treatment immediately following acute treatment response) is now considered the standard of care to prevent relapse.^{13 - 15}

Optimal clinical management of depressive illness is not established once 6 to 9 months of continuation therapy are completed. A history of prior depressive recurrences, subsyndromal symptoms, depression secondary to other comorbid psychiatric disorders, socioeconomic status, severity of depression, and chronicity of depression are all risk factors that predict a higher likelihood of recurrent depression.^{14 - 16} The presence of 1 of these risk factors suggests that further maintenance antidepressant therapy might be required. Several studies provide strong support for the prophylactic efficacy of maintenance antidepressant therapy in patients with a history of multiple prior depressive episodes.^{11 ,16 - 18}

But no adequately designed studies are available that examine the efficacy of maintenance therapy in the common subgroup of patients with chronic depression of at least 2 years' duration.

Currently, the majority of all new prescriptions written for depressed patients are for the selective serotonin reuptake inhibiting (SSRI) class of antidepressants.¹⁹ Our study was designed to provide the first randomized placebo-controlled test of the safety and sustained prophylactic efficacy of maintenance treatment with an SSRI antidepressant, in this case sertraline hydrochloride, in the high-risk patient group who have been diagnosed as having chronic depression.

Subjects were patients who had responded to sertraline after participation in 1 of 2 prospective, 12-week acute treatment studies. The results of the 12-week study are presented in a separate report.²⁰ The maintenance study reported here was conducted at 10 academic centers and 2 clinical research centers from September 1993 to November 1996. Outpatients meeting a structured clinical interview diagnosis of chronic major depression (of at least 2 years' duration), or dysthymic disorder with a concurrent diagnosis of major depression ("double depression") based on the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R) were enrolled. Patients who had a minimum baseline severity of 18 on the 24-item Hamilton Depression scale (HAM-D) after a 1-week single-blind placebo lead-in were initially entered into the 3-phase protocol. During the acute phase, patients were randomized in the double-blind study to 12 weeks of treatment with either sertraline hydrochloride or imipramine hydrochloride in a 2:1 ratio. Patients next entered a 4-month continuation phase if, at the end of the acute phase, they fell into either (1) the full remission response category, which is operationally defined as achieving a final HAM-D total score of 7 or less and a Clinical Global Impressions (CGI) improvement score of 1 or 2 (very much or much improved) or (2) the satisfactory therapeutic response category, which is operationally defined as achieving a reduction of 50% in the final HAM-D total score, as well as a score of 15 or less, a CGI improvement score of 2 or less, and a CGI severity score of 3 or less. Of the patients who received the sertraline treatment, 209 (49.1%) of 426 both completed 12 weeks of acute treatment and met full or satisfactory response criteria. These 209 patients were eligible for entry into the continuation phase of treatment.

Patients were eligible to enter the maintenance phase reported if they had sustained at least a satisfactory antidepressant response to sertraline through the end of continuation therapy.

The subjects entering the maintenance phase represent only the subset of subjects who had been treated with sertraline continuously since they entered into the acute phase of the study. For patients who received imipramine during the acute treatment phase, 98 (46.9%) of 209 both completed the 12 weeks of acute treatment and met the full or satisfactory response criteria. To maintain blinding, this group of patients continued (as a parallel but nonrandomized group) receiving imipramine during subsequent continuation and maintenance phases. Those taking either sertraline or imipramine who failed to improve during the acute phase treatment were entered into the crossover phase of the study, with sertaline nonresponders switched to imipramine, and imipramine nonresponders switched to sertraline. The integrity of the study's double-blind component was not compromised. Thirty (60%) of 51 patients treated with sertraline in the crossover phase of the study responded, while 52 (44%) of 117 patients treated with imipramine during the crossover phase responded. These crossover patients have also not been included in this report because the differential sequencing of study treatments made them noncomparable. Results from these parallel continuation and crossover phases of treatment will be the subject of separate reports.

The maintenance study was approved by the institutional review board at each of the 12 collaborating centers. Separate written informed consent was obtained for the maintenance phase. The design of this phase consisted of random, double-blind assignment to parallel groups for 76 weeks of treatment with either sertraline hydrochloride (in a flexible daily dose of 50 to 200 mg) or placebo. Patients randomized to the latter group tapered sertraline use via placebo substitution at a 50 mg/wk rate of reduction.

Randomization was stratified by high and low probability of recurrence based on the 2 following variables hypothesized to be predictors of increased probability of depression recurrence: (1) presence of residual depressive symptoms (operationally defined as a HAM-D score ≥10 and a CGI severity score ≥ 3) at the end of continuation treatment; and (2) a history of 2 or more prior major depressive episodes.

Patients were evaluated and rated every 2 weeks for the first 12 weeks, and then monthly thereafter. If patients' depression worsened, their visit frequency could be increased to once a week.

Assessment instruments included clinician-rated instruments designed to systematically measure various aspects of the antidepressant's efficacy, which included the 24-item version of the HAM-D,²¹ which assesses core, as well as associated or secondary, symptoms of depression; the Montgomery-Åsberg Depression Rating Scale,²² which assesses core symptoms of depression; the Cornell Dysthymia Scale,²³ which assesses dysthymic symptoms; and the CGI severity and improvement scales.²⁴ These measures, together with the patient-rated Beck Depression Inventory,²⁵ which assesses severity of depression with an emphasis on cognitive depressive symptoms, and the Patient Global Evaluation²⁴ were completed on a monthly basis. In addition, the HAM-D and CGI scales were completed every 2 weeks during the first 12 weeks of the study.

Various scales assessing quality of life and psychosocial functioning were also administered. Details on these measures and the effect of study treatment on these measures will be presented in a later article.

Reports of depression exacerbations triggered an appointment within 1 week. Patients were considered to have an impending recurrence of depression if, at either a scheduled or unscheduled assessment visit, they met all the following criteria: (1) DSM-III-R criteria for major depression for at least 3 weeks; (2) CGI severity score of 4 or more (at least moderate severity); (3) CGI improvement score of 3 or more (minimally improved or less); and (4) an increase in HAM-D to a score of 4 or more points higher than the maintenance phase baseline. Such patients were rescheduled for a second visit within 1 week (total duration of clinical worsening criteria of at least 4 weeks) and were declared to have experienced a recurrence if they continued to meet all the above criteria and if a senior investigator who interviewed the patient had concurred with the conclusion that the patient had experienced a recurrence of major depression.

Patients meeting recurrence criteria could continue in the study if both patient and study physician agreed that no change in the study medication was indicated at that time. Instead, an increase in daily dose was undertaken at a rate of 50 mg/wk up to the maximum daily dose of 200 mg of sertraline hydrochloride. A similar double-blind titration was also used for patients receiving placebo treatment. Patients experiencing exacerbations of depression but who did not meet strict recurrence criteria also were managed using this procedure. If this titration procedure failed or if the patient was already receiving the maximum tolerable or permissible dose and a change of treatment was felt to be indicated, then patients who met recurrence criteria were discontinued from the study.

Three time-to-event outcome variables constituted the primary focus of the research reported herein. The first variable, specified as the primary end point of the trial a priori was time to recurrence of a major depressive episode. We also used 2 less stringent, post hoc end points because they reflected clinically relevant trigger points for treatment interventions in the long-term management of depression. They are time to reemergence of clinically significant depression and time to reemergence of first symptoms of depression. Establishment of the 2 less stringent end points was accomplished after a blinded review of HAM-D, GCI, and an overall clinical picture of all patients who discontinued the study prematurely. Agreement among 6 (75%) of 8 senior investigators was required for a patient to be categorized as having met the 2 post hoc clinical end points.

Baseline homogeneity of the 2 intent-to-treat randomization groups was confirmed with statistical tests appropriate for continuous and categorical variables, always taking into account the effect of study site and randomization stratification factor. Those who responded to sertraline and who were entering the maintenance phase (both randomization groups combined) were also compared with patients originally randomized to receive sertraline at the start of the acute phase but who were not entering maintenance phase, with respect to the same background, clinical, and demographic variables. We applied the analysis of variance (ANOVA) and Cochran-Mantel-Haenszel methods to these comparisons, adjusting for both the study site and for the stratification factor.

The primary objective of the maintenance phase was to compare the efficacy and safety of continuing sertraline treatment vs placebo substitution in preventing recurrence of major depression in patients experiencing chronic depression. The primary efficacy end point, defined a priori, was time to recurrence of major depression. Secondary efficacy end points, also defined a priori, included change from baseline in the symptom severity ratings. These assessments were obtained at multiple visits throughout the maintenance phase. The results of these scores are reported herein for the patient's last or end point assessment for each severity rating. Secondary end points also included the post hoc, time-to-event variables, consisting of time to reemergence and time to first signs of depression. These were post hoc end points that were defined (prior to breaking the study blind) to be confirmatory of the primary outcome as a consequence of the low rates of protocol-defined recurrence overall in the study. These secondary, post hoc end points were established as a more sensitive measure of outcome that could detect a treatment difference in the absence of the more stringent primary end points.

The primary analysis consisted of a comparison of the time to recurrence of depression for patients taking sertraline and patients taking placebo based on the log-rank χ² test statistic for differences in time-to-failure distributions, which were stratified on the probability of recurrence. Patients who discontinued the study early were censored at their time of discontinuation. Kaplan-Meier method estimates of the time-to-failure distributions were produced for descriptive purposes. Median failure times and estimates of the cumulative failure probabilities at 8, 24, 52, and 76 weeks of maintenance therapy were derived from the Kaplan-Meier distributions, also for descriptive purposes. The secondary time-to-failure outcomes (time to reemergence and time to first signs of depression) were similarly analyzed.

Secondary efficacy measures corresponding to the specified symptom severity ratings were analyzed for between-treatment-group differences at each patient's last, or end point visit. Comparisons were made in the context of analysis of covariance (ANCOVA) models fit to change-from-baseline values, which were adjusted for study site, randomization, stratification factor, and maintenance phase baseline values. Site-by-treatment interactions were assessed in a second model fit to each outcome. The changes within treatment groups from the maintenance phase baseline to the end point with respect to each outcome measure were assessed by 1-sample paired t tests.

Secondary analyses of time to recurrence and time to reemergence of clinically significant depression were conducted to assess the effects of additional covariates on treatment failure. Adjusted relative risk ratios for treatment were calculated based on Cox proportional hazards regression models that included effects for pooled study site, type of depression (chronic major vs double depression), and randomization strata (high vs low risk of recurrence). Additionally, proportional hazards regression models were fit in a forward stepwise fashion to assess the importance of a wide range of potential predictors on time to recurrence and time to reemergence. Potential interactions of significant predictors with treatment were assessed in the context of these reduced models. For all proportional hazards models used to estimate adjusted relative risks, the assumption of proportionality was confirmed via tests of interactions between time to outcome and treatment and between time to outcome and significant covariates.

Results of an exploratory analysis, specified post hoc, examining the effects of withdrawal from sertraline treatment were based on the Fisher exact test for differences in the proportions of patients in the sertraline and placebo groups who experienced recurrence in the first 4 weeks following randomization.

Among the 209 patients who responded to sertraline and who began the 4-month continuation phase, 179 of them completed the continuation phase, 169 met criteria for remission or satisfactory response in the opinion of the investigator, and 161 enrolled in the maintenance treatment trial. These 161 patients constitute the analysis sample for all the data analyses presented in this study. They were assigned to receive either sertraline (n=77) or placebo (n=84). Figure 1 schematically summarizes the study design and the patients available at each phase of the study.

At the end of the continuation trial, there were no significant differences in efficacy measurements between patients diagnosed as having chronic major depression or double depression. Consequently, these patient groups were combined. Table 1 summarizes the demographic and clinical characteristics measured at baseline for patients randomized to receive sertraline treatment at the start of the acute phase but excluding patients entering the crossover treatment group. Summaries are shown both for patients entering the maintenance phase by treatment group (n=77 for sertraline; n=84 for placebo; N=161, total), and for patients discontinuing prior to the maintenance phase (n=148). There were isolated differences between these 2 groups, including the tendency of patients entering the maintenance phase to be better educated (P=.03), more likely to be married (P=.01), and to have had prior psychotherapy (P=.03) than patients not entering the maintenance phase.

The 2 maintenance phase treatment groups were also similar in the variables we examined, with a few exceptions. Patients in the placebo group were less likely to have a past history of panic disorder (P=.02) and, among the patients with double depression, placebo patients reported a shorter duration of current major depression than those randomized to the sertraline group (P=.03).

Effects of Sertraline Discontinuation After 7 Months of Acute Plus Continuation-phase Treatment.— The effect of tapered discontinuation of sertraline during the first 4 weeks of maintenance phase treatment was examined to assess whether medication withdrawal accelerated the recurrence rates. Eleven patients (13%) in the placebo group experienced a reemergence of depression during the first 4 weeks after randomization compared with 7 (9%) of those who continued taking sertraline (P=.55).

The mean final dose of sertraline hydrochloride was 146.1 mg. The mean final number of placebo pills taken was 3.4. The mean final sertraline hydrochloride dose in the maintenance phase did not differ significantly from the mean final dose in the acute treatment phase (141.6 mg) (n=77; P=.47 from 1-sample t test; not significant).

Adverse Events and Attrition.— In general, maintenance treatment with both sertraline and placebo were well tolerated, lending support to the integrity of the double-blind. There were no differences overall in the incidence of adverse event reporting between the 2 treatment groups (62/84 patients taking placebo vs 62/77 patients taking sertraline reported at least 1 adverse event; P=.31). Table 2 presents treatment-emergent adverse events reported in at least 10% of patients in either treatment group. Significant differences were observed with respect to pain and sexual dysfunction, with more patients treated with sertraline reporting sexual dysfunction and more patients treated with placebo reporting pain. Only 8 patients (10.4%) treated with sertraline, compared with 1 patient (1.2%) treated with placebo, dropped out citing adverse events as the reason (P=.01; Fisher exact test). Other reasons cited for dropping out of the study that were unrelated to recurrence or depression symptom reemergence were similar for both groups. Only attrition due to insufficient response and attrition due to adverse events were statistically significant. Attrition related to consensus determination of treatment failure is reported below.

End Point Analysis of Symptom Severity Ratings for the Intent-to-Treat Sample.—Table 3 provides mean scores at entry into the acute and maintenance phases and at end point. No significant differences were detected between treatment groups at entry into the maintenance phase. By contrast, maintenance sertraline resulted in significantly better outcomes on all 6 symptom measures. This reflects a broad improvement across all symptom dimensions of depressive illness, including cognitive (Beck Depression Inventory), core (HAM-D, Montgomery-Åsburg Depression Rating Scale), and accessory (HAM-D) symptoms of major depression, symptoms of dysthymia (Cornell Dysthymia Scale), and global symptoms (CGI). There were no significant treatment-by-center interactions.

Treatment Efficacy: Recurrence Rates and Time to Recurrence of Major Depression.—Table 4 summarizes major depression recurrence rates observed during maintenance treatment by the a priori definition of recurrence and consensus ratings. The stringent definition (requiring 3 weeks of treatment and a confirmatory second evaluation 1 week later by an independent senior investigator) yielded a low rate of protocol-defined recurrences at end point for both sertraline (6% [5/77]) and placebo (23% [19/84]). This unexpectedly low rate of recurrence was probably due to attrition from the study prior to meeting stringent recurrence criteria. The time to recurrence was significantly delayed for patients treated with sertraline compared with those treated with placebo (P=.002), stratifying for patients who are at high risk vs those who are at a low risk of recurrence. Similar significant benefit for sertraline was found using the less stringent consensus definitions of reemergence of depression symptoms (P=. 001) and first symptoms of depression (P<.001). Only 20 (26%) of the 77 patients taking sertraline experienced reemergence of depression compared with 42 (50%) of 84 patients taking placebo, and only 26 (34%) of 77 patients taking sertraline showed first signs of depression compared with 50 (60%) of 84 patients taking placebo.

Table 5 presents the cumulative survival probabilities for recurrence and reemergence of depression at periodic intervals during maintenance follow-up. By the eighth week of maintenance treatment, the survival distributions began to separate, with sertraline providing patients with significantly better prophylaxis than placebo at all points thereafter. The median time to recurrence or reemergence is not defined for sertraline patients because less than 50% of these patients experienced either event. The median survival time to reemergence among patients taking placebo was 26 weeks (95% confidence interval [CI], 14 to undefined). Figure 2 shows the Kaplan-Meier estimates of the survival distributions for both treatment groups, with the 3 panels illustrating comparisons for the primary and secondary time-to-failure outcomes.

The adjusted relative risk of placebo treatment was estimated under the assumption of proportional hazard rates for time to recurrence and time to reemergence of depression. Patients receiving placebo were 2.18 (95% CI, 1.27-3.74) times as likely to experience reemergence of depression, and 4.07 (95% CI, 1.51-10.95) times as likely to experience depression recurrence as patients taking sertraline during maintenance therapy, adjusting for pooled study site, type of depression, and randomization strata (P=.005 for both outcomes).

Attrition also was significantly higher among patients receiving placebo than among those taking sertraline. Approximately 6 months into the maintenance phase, almost half of the patients taking placebo had discontinued the study, compared with only 31% of patients taking sertraline. By study end, 24 (29%) of 84 patients taking placebo remained in the study, compared with 35 (45%) of 77 patients taking sertraline. The median time of discontinuation among patients taking placebo was 24 weeks (95% CI, 15-40) compared with 53 weeks (95% CI, 32 to undefined) among patients taking sertraline (P<.02).

Effects of Clinical Covariates on Symptomatic Reemergence and Episode Recurrence.— We examined the potential influence of a number of clinical variables on recurrence and reemergence rates by fitting Cox proportional hazards regression models to time-to-event data.

Various clinical covariates were entered into a stepwise proportional hazards regression model to determine the following: (1) whether any of the covariates considered were significant predictors of time to reemergence and time to recurrence and (2) whether any of the covariates considered had a significant interaction with treatment. For reemergence of depression, longer duration of dysthymia was the only significant predictor (P=.004), although a trend was also evident for higher acute baseline CGI severity (P=.06). Controlling for duration of dysthymia, the treatment effect is still very strong (relative risk, 2.18; 95% CI, 1.27-3.72; P=.005), indicating little or no confounding of the treatment effect from this covariate. Moreover, the 2-way interaction was not significant (P=.46). The only significant predictor of time to recurrence was higher acute baseline CGI severity (P=.01). Again, this effect did not diminish the treatment effect (relative risk, 5.13; 95% CI, 1.89-13.96; P=.001), and the severity by treatment interaction was not significant (P=.99).

The risk of reemergence of depression during placebo treatment among patients experiencing their first episode was relatively low (40% [10/25]) compared with patients with recurrent episodes of major depressive disorder (55% [32/58]). By contrast, sertraline was equally effective for patients in these subgroups with 9 (29%) of 31 first-episode patients experiencing a depression reemergence episode and 11 (24%) of 46 patients experiencing a depression reemergence. Although the drug-placebo difference in prophylactic efficacy was higher for patients with recurrent depression (ie, 31% vs 11%), the treatment-by-prior episode events interaction analysis was not statistically significant (P=.25) in predicting time to reemergence, more likely because of low power resulting from low event rates.

Finally, it should be noted that entry criteria permitted patients with HAM-D scores as high as 15 to enter the maintenance phase treatment. In fact, only 24 patients (14.9%) had HAM-D total scores above 10 at the start of maintenance phase treatment, suggesting that only a small subset of patients entered with a substantial degree of residual depressive symptoms. Consistent with this, 80% of patients entered the maintenance phase with a sustained remission of at least 4 months' duration (operationally defined by a Longitudinal Interval Follow-up Evaluation score²⁶ of "1" or "2" indicating at most mild residual depressive symptoms). Given this low level of residual depressive symptoms, it is not surprising that the presence of such residual symptoms was not found to predict a higher rate of depressive reemergence or recurrence.

This multicenter, placebo-controlled, randomized trial is the first to report on the maintenance phase efficacy of an SSRI antidepressant in patients experiencing chronic depression. The results of this study demonstrate unequivocally that sertraline protects against recurrence or reemergence of depression and considerably extends the time in remission for this high-risk population. The results are consistent across all outcome measures and across 3 different criteria for recurrence or reemergence of depression. Sertraline was very well tolerated during long-term use, although adverse events caused numerically higher and statistically significant attrition (n=8) than did placebo (n=1).

One of the most widely accepted tenets of modern psychopharmacology is the value of maintenance treatment of major depression. And yet this de facto consensus treatment strategy remains largely an article of faith, resting as it does on a tenuous empirical base of a small number of placebo-controlled studies totaling fewer than 600 patients. In fact, the only published maintenance treatment studies of longer than 12 months used tricyclic or monoamine oxidase inhibitors.^{16 - 18 ,27}

The patients treated in our study not only had chronic depression but also had high levels of comorbidity, past substance abuse, moderate to high depressive symptom severity, and marked functional impairment. Most had been ill their entire adult lives.

In light of such chronicity, severity, and comorbidity, relatively vigorous doses of sertraline hydrochloride (eg, an initial mean maintenance dose of 139 mg) were used. It should be noted that the current report summarizes results for the maintenance phase of a long-term treatment study. As a result, patients who were so sufficiently intolerant of sertraline that they discontinued treatment were not available for entry into this phase of the study. Similarly, patients were also not available who improved during the acute or continuation phases sufficiently enough that they were unwilling or unable to meet the commitments of an arduous maintenance protocol. Therefore, as favorable as the results are for sertraline in long-term antidepressant prophylaxis, it should be emphasized that the current results examine only a 38% subset (161/426) of the patients initially randomized to receive sertraline in the acute phase.

Severity of depression prior to the initial acute phase treatment was the only significant predictor of early recurrence of depression (P<.02). Surprisingly, the number of prior episodes and the presence of residual depressive symptoms were not associated with an increased rate of depression recurrence, although patients with recurrent depression did have a higher recurrence risk while taking placebo, and sertraline did provide the greatest relative prophylactic benefit in this group.

For reemergence of depression, longer duration of dysthymia was the only significant predictor (P=.004), although higher acute phase baseline depression severity was trending toward significance (P=.06). The influence of dysthymia as a covariate raises issues about the appropriateness of combining the patients diagnosed as having double depression and those with chronic major depression. However, no between-group differences existed at maintenance phase baseline and, in fact, the treatment effect observed for sertraline remained strong after controlling for dysthymia duration (P=.005).

The reemergence of depression in patients treated with placebo was approximately 2-fold higher than what was observed for patients treated with sertraline. It is perhaps remarkable that nearly 50% of a patient sample entering the study with a mean of approximately 10 years of major depression, or 25 years of dysthymia, managed not to relapse during 18 months of placebo treatment. The repeated study visits and duration of contact with mental health professionals at each visit may have contributed to the relatively low recurrence rate in the placebo group, but it is possible that chronicity, if aggressively treated with acute and continuation therapy, is simply less strong of a risk factor for subsequent depression recurrence than is an established history of multiple prior recurrences. The recurrence risk associated with the latter is confirmed by maintenance treatment studies that have reported higher recurrence rates (70%-80%) for patients receiving placebo,^{11 ,16 - 18} as well as results from the National Institute of Mental Health Collaborative Depression Study, which identified a high number of prior episodes as a predictor of increased risk of recurrence.¹⁶

Alternatively, it may be that the patients treated with an SSRI antidepressant such as sertraline are prone to discontinuation-emergent relapse, as has been proposed to occur on discontinuation of tertiary amine tricyclics.^{28 - 29} The results from the only published SSRI maintenance of treatment study¹¹ are consistent with this hypothesis, as they observed a 57% 12-month recurrence rate during placebo treatment despite an average of 3.8 prior episodes of depression.

Sertraline has previously been shown to be effective in the prevention of relapse in patients experiencing nonchronic episodes of major depression in a 44-week placebo-controlled continuation study.¹² Our study extends these results to an 18-month, placebo-controlled maintenance-discontinuation study that followed 7 months of acute and continuation treatment. The results of this study demonstrate the sustained efficacy of sertraline as a maintenance treatment for the prophylaxis of recurrence or reemergence of depression in patients who are at high risk for recurrences due to chronicity of depression, comorbidity, or established history of multiple previous episodes. Whether these results are specific to sertraline, or generalize to SSRI antidepressants as a class, will need to be clarified in further maintenance treatment studies.