Early Detection of Depression

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By John W. Feightner
39                    Early Detection of Depression
                        Prepared by John W. Feightner, MD, MSc, FCFP1

                                   Depression is a common problem that carries a high burden
                             of suffering, which can include death from suicide. Effective
                             treatment is available. However, in 1990 as in 1979 the Task
                             Force recommended that routine screening for depression in
                             asymptomatic individuals be excluded from periodic health
                             assessments based on fair evidence that such screening by
                             questionnaire did not improve detection rate or manage-
                             ment.<1,2> However, physicians should be sensitive to the
                             possibility of depression in their patients, particularly those at
                             higher risk.

                             Burden of Suffering
                                    Depression is frequently encountered in family practice and in
                             ambulatory care settings. The lifetime prevalence of clinically significant
                             depression is 15% to 30%; it is about twice as common among women
Depressed                    as among men. The prevalence in the general population ranges
individuals frequently
                             between 3.5% and 27% depending on the definition used and the
present with physical
symptoms, making
                             population studied; however, it is thought to have increased among
diagnosis more               children and adolescents. People who are single, divorced, separated,
difficult, particularly in   seriously ill, recently bereaved or those with a family history of
the early stages of          depression have a greater incidence than others. Depressed individuals
mild cases                   frequently present with physical symptoms, which may make diagnosis
                             more difficult, particularly in the early stages and in mild cases.
                             Important episodes of depression have been overlooked, so that
                             instead of recognizing and treating the problem diagnostic testing or
                             treatment for other illnesses is performed. Depression has a significant
                             effect on the patient’s quality of life and productivity, but psychiatric
                             referral also has some negative implications regarding societal
                                   Spontaneous remission can occur over 6 to 12 months in up to
                             50% of affected people; however, about 50% of those who suffer from
                             major depression become chronically depressed. Affected people are
                             more likely than others to be suicidal: 30% to 70% of people who
                             have committed suicide were previously identified as having major
                             depression. In Canada, in 1986, suicide accounted for an estimated
                             97,600 potential years of life lost among men and another 25,300
                             years among women.

                                 Professor of Family Medicine, McMaster University, Hamilton, Ontario

       The gold standard for diagnosing depression is careful application
of standardized clinical criteria. In the primary care setting the problem
must be recognized first and then properly evaluated. Several short
(12-38 item), self-administered questionnaires have been proposed            For many
                                                                             instruments, validity
to assist with early recognition. When evaluated, these question-
                                                                             has not been fully
naires have been generally sensitive to changes in clinical status but       established
correlation with other tests or with clinical assessment has ranged
from 0.40 to 0.89, with sensitivity 64-91% and specificity 56-82%.
Hence, for many instruments, validity has not been fully established.

Effectiveness of Early Detection and
       Once identified, depression can be treated effectively with
medication and psychotherapy; however, there is no conclusive
evidence that treatment in the early stages of depression has greater
long-term effects than intervention started later in the course of the
        Four randomized controlled trials have evaluated whether
routine use of a screening questionnaire provided any benefit in terms
of detection and management of depression. Shapiro and associates
asked 1,242 patients attending an inner-city primary care teaching
facility to complete the General Health Questionnaire (GHQ) before
seeing a physician.<3> The provision of the GHQ information to the
physician had no statistically significant effect on the detection of
psychologic problems except among patients over 65 years of age.
There was no ultimate effect on patient management, even in the
group over 65 years of age.
      Hoeper and collaborators found that physicians’ knowledge of a
“positive” GHQ result had no effect on the detection of psychologic
distress among 1,469 patients in a Wisconsin primary care office.<4>
       Using somewhat weaker methods in terms of identification of
case and control subjects and choice of outcome measures, Johnstone
and Goldberg used the GHQ to assess 1,093 patients.<5> New
episodes of psychiatric illness were diagnosed and treated in 16% of
the patients without data from the GHQ; an additional 11% were
identified for treatment after the GHQ results were reviewed.
       Zung and colleagues found that physicians informed of positive
scores of the Zung Self-Rating Depression Scale detected depression
in more patients (68% of 102) than when they were not informed of
the results (15% of 41).<6> However, there were significant flaws in
the design and execution of this study, particularly in terms of losses
to follow-up.

                                In a well designed, randomized controlled trial, Magruder-Habib
                         and coworkers used the Zung Self-Rating Depression Scale and a
                         DSM-III screen to evaluate depression status in a group of subjects
                         over age 45 attending a U.S. Veterans’ Administration general medical
                         clinic over a 12 month period.<7> Providing physicians with scores
                         for patients whose depression was unrecognized in the clinical setting
                         had an important impact on eventual recognition and management.
                         However, in order to reduce the number of false positives, only
                         patients scoring positive on both self-rating scale and a research
                         assistant administered DSM-III checklist were identified to the
                         attending physician. Hence, while the self-assessment instrument may
                         be feasible in a primary care setting, the study does not evaluate the
                         effectiveness or the impact of this instrument alone on the recognition
                         and management of depression. The study did, however, provide
                         valuable insight into the impact of informing physicians about
                         unrecognized depression, and in conjunction with the Shapiro study
                         indicates that further studies would be of value.

                         Recommendations of Others
                                The U.S. Preventive Services Task Force does not recommend
                         routine screening but encourages physicians to have a high level of
                         clinical suspicion.<8>

                         Conclusions and Recommendations
                                Overall, these five trials fail to provide adequate evidence to
                         support the use of routine screening tests for the early detection of
                         depression. In fact, the current evidence supports not routinely using
While routine            screening instruments but rather to maintain a high level of clinical
screening isn’t
effective, physicians
should be sensitive to
the possibility of
depression in their
                         Unanswered Questions (Research Agenda)
patients                 The following have been identified as research priorities:
                          1.   Conducting research into improved methods of identifying
                               people at high risk for depression and developing a simple
                               diagnostic test for use in this group by primary caregivers.
                          2.   Evaluating the impact of questionnaires in the early detection of
                               depression and subsequent management of patients over
                               65 years of age.

                              The literature was identified with a MEDLINE search up to May
                         1993 using the following MESH headings: depression, mass screening.

      This review was initiated in November 1992 and updates a
report published in May 1990.<1> Recommendations were finalized in
January 1994.

     The original Task Force report was co-authored by Dr. Graham
Worrall, MSc, DRCOG, MRCGP, CCFP, visiting lecturer, Community
Medicine, Memorial University, St. John’s, Newfoundland.

Selected References
 1.   Canadian Task Force on the Periodic Health Examination: The
      periodic health examination, 1990 update: 2. Early detection of
      depression and prevention of suicide. Can Med Assoc J 1990;
      142: 1233-1238
 2.   Feightner JW, Worrall G: Early detection of depression by
      primary care physicians. Can Med Assoc J 1990;
      142: 1215-1220
 3.   Shapiro S, German PS, Skinner EA, et al : An experiment to
      change detection and management of mental morbidity in
      primary care. Med Care 1987; 25: 327-339
 4.   Hoeper EW, Nycz GR, Kessler LG, et al : The usefulness of
      screening for mental illness. Lancet 1984; 1: 33-35
 5.   Johnstone A, Goldberg D: Psychiatric screening in general
      practice. Lancet 1976; 1: 605-608
 6.   Zung WW, Magill M, Moore JT, et al : Recognition and treatment
      of depression in a family medicine practice. J Clin Psychiatry
      1983; 44: 3-6
 7.   Magruder-Habib K, Zung WW, Feussner JR: Improving
      physicians’ recognition and treatment of depression in general
      medical care. Med Care 1990; 28(3): 239-250
 8.   U.S. Preventive Services Task Force: Guide to Clinical
      Preventive Services: an Assessment of the Effectiveness of
      169 Interventions. Williams & Wilkins, Baltimore, Md, 1989:

        S   U   M     M   A   R Y       T   A   B      L   E     C   H   A   P     T   E   R     3 9

                          Early Detection of Depression

  MANEUVER                    EFFECTIVENESS                LEVEL OF EVIDENCE           RECOMMENDATION
  General Health              Routine testing for          Randomized controlled       Fair evidence to
  Questionnaire and           depression by                trials<3-6> (I)             exclude testing from
  Zung Self-rating            questionnaire did not                                    periodic health
  Depression Scale            improve detection rate                                   examination of
                              or management.                                           asymptomatic
                                                                                       people (D)