SHORT REPORTS |
Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki
Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, and Department of Psychiatry, HUCH, Peijas Hospital, Health Care District of Helsinki and Uusimaa, Vantaa
Department of Mental Health and Alcohol Research, National Public Health Institute, Helsinki, and Department of Psychiatry, Helsinki University Central Hospital, Helsinki, Finland
Correspondence: Erkki T. Isometsä, MD, PhD, Institute of Clinical Medicine, Department of Psychiatry, P.O. Box 22 (Välskärinkatu 12 A), 00014 University of Helsinki, Finland. Email: erkki.isometsa{at}hus.fi
None. Funding detailed in Acknowledgements.
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Screening and baseline evaluation
In the first phase of the study, 806 psychiatric secondary care patients
(aged 20–60 years) in the City of Vantaa, seeking treatment, referred to
from primary care or already receiving psychiatric care but showing signs of
deteriorating clinical state, were screened for the presence of depressive
symptoms between 1 February 1997 and 31 May
1998.7 Of the 703
eligible patients, 542 (77%) gave written informed consent and participated.
In the second phase, researchers interviewed these patients using the Schedule
for Clinical Assessment in Neuropsychiatry (SCAN) version
2.0;10 269 patients
were subsequently diagnosed with DSM–IV major depressive
disorder11 and
included in the study. The diagnostic reliability of the diagnosis was
excellent
(kappa=0.86).7
Follow-up
After baseline, participants were investigated at 6 and 18 months with
SCAN, and at 5 years with Structured Clinical Interview for
DSM–IV–TR Axis I Disorders
(SCID–I/P),12
plus several semi-structured
scales.6,8,9
The exact duration of the index episode, the timing of recurrences and
treatment were examined by gathering all available data, a best estimate of
which was integrated into a graphic life-chart. In addition to the follow-up
interviews, patient records were also available. Questions related to
important life events were asked to investigate changes in psychopathological
state.
We classified the patients follow-up time in the life-chart into
three categories: (a) full remission (none of the 9 major depressive episode
criteria symptoms), (b) partial remission (1–4 of the 9 symptoms) or (c)
major depressive episode (
5 of the 9 symptoms). Recurrence was defined as
return of symptoms sufficient to fulfil criteria for major depressive episode
after at least two consecutive months of partial or full remission.
Self-reported adherence and attitudes towards treatments were assessed by
interviewing and rated on ordinal
scales.9
Specifically, adherence to antidepressant treatment during the first 6 months
was used as a measure of acute-phase pharmacotherapy adherence and classified
based on whether the patient used them: (a) regularly, treatment adherence
adequate with respect to treatment goals; (b) somewhat irregularly, unclear
whether this would affect treatment goals; (c) very irregularly, the treatment
did not proceed according to plan; and (d) not at all, the treatment could not
be implemented. Social relationships were investigated with the Interview
Measure of Social
Relationships.13
Of 269 participants initially included in the cohort, 198 participated in the 18-month interview and 182 (67.7%) in the 5-year interview. In all, information on 218 participants, followed for up to 60 months or until they left the study, was analysed. We defined an indication for maintenance treatment to exist after a major depressive episode among patients having already had more than three lifetime major depressive episodes and then achieving full remission for more than 2 months. Treatment was to commence 4 months after onset of full remission (i.e. after the continuation treatment phase).
Statistical methods
We used SPSS software, version 14.0 for Windows, and
2
(with Yates correction), Fishers exact, Mann–Whitney and
Kruskal–Wallis tests, plus the two-sample t-test when
appropriate. Logistic regression was used to investigate predictors for
receiving maintenance treatment. From a predetermined set of twelve predictors
covering the domains in the online Table DS1, the non-significant variables
were eliminated from the final model, but age, gender and length of
maintenance indication (months) were controlled for.
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In univariate analyses, maintenance treatment was predicted by numbers of previous episodes, comorbid Axis I–III disorders and mental disorders, severity of anxiety, anxiety disorders, panic disorder, social phobia, avoidant personality disorder, positive medication attitude, good adherence during the acute phase and higher income (online Table DS1). However, in multivariate logistic regression analyses, only good antidepressant adherence in the acute phase (OR=3.18; 95% CI 1.12–9.03, P=0.030) independently predicted maintenance treatment.
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Our study had some major strengths. It comprised a cohort of patients representing psychiatric out- and in-patients with major depressive disorder in a Finnish city and is up to date in terms of the use of DSM–IV, modern antidepressants and maintenance treatment recommendations.1–4,7,9 Structured and semi-structured measures plus life-charts, a prerequisite for this type of study, were used. However, limitations also exist. Those participants who left the study did not differ in their outcome, at least during the time they participated, from those who remained in the follow-up. Although we had full access to patient records, a long interval between the last two interviews (3.5 years) may have affected the accuracy of information regarding longitudinal outcome. We may have slightly underestimated the recurrence rate (and thus onset of maintenance indication) during this period.6 Minor inaccuracies may also exist regarding treatment information; participants may not always have recalled information on treatment precisely or reported adherence honestly. However, data from participants or from their records were carefully compared and combined. Finally, we defined the indication for maintenance pharmacotherapy to begin after three lifetime major depressive episodes, and a different threshold could change the findings. However, setting it to lifetime fourth or fifth episodes in sensitivity analyses resulted in quite similar (61.5 and 62.9% respectively) proportions of patients having received maintenance treatment.
To ensure generalisability, replication of these findings is necessary. Nevertheless, they are important from a public health perspective. In secondary care, maintenance treatment is received by those able to adhere to their treatments, a finding which highlights the interactive nature of continuity of treatment. The tertiary preventive impact of maintenance treatment for major depressive disorder seems currently limited, as many patients may either not receive it or receive it for too short a period.
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