Epidemiology of Depression in MS

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Epidemiology of Depression in MS
Scott B. Patten MD, PhD. Associate
Professor, University of Calgary.
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Depression - Definitions

• A description of mood
• A clustering of symptoms
• A mood disorder

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Depression As a Mood Disorder

• Major Depressive Disorder
• Dysthymic Disorder
• Bipolar I Disorder
• Bipolar II Disorder
• Adjustment Disorders
• Organic Mood Disorders
• Secondary to Medical Condition
• Substance-induced Mood Disorder

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Depression As a Mood Disorder

• Major Depressive Disorder
• Dysthymic Disorder
• Bipolar I Disorder
• Bipolar II Disorder
• Adjustment Disorders
• Organic Mood Disorders
• Secondary to Medical Condition
• Substance-induced Mood Disorder

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DSM-IV Major Depression

• Certain depressive symptoms
• They should be severe and persistent
• The symptoms are NOT due to
• Bereavement (grief)
• Physical causes

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• Depressed mood (sadness, tearfulness)
• Loss of interest (anhedonia)
• Sleep problems
• Appetite/weight changes
• Changes involving physical movement
• Changed thinking style (e.g. hopelessness)
• Problems with concentration memory
• Fatigue
• Thoughts about death and/or suicide

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Epidemiological Definitions Prevalence

• Prevalence
• Proportion of a population with a disease or
  outcome at a point in time (point prevalence)
• Proportion of a population with a disease or
  outcome during an interval of time (period
  prevalence)
• Proportion of a population having developed an
  outcome at any previous time (lifetime
  prevalence)

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General Population MD Prevalence

• Point Prevalence 1.5
• Annual Prevalence 5
• Lifetime Prevalence 10

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Major Depression Prevalence in MS
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Epidemiological Solutions?

• Sampling directly from the population
• Achieving larger sample sizes
• Use of large-scale general health survey data
• The Canadian Community Health Survey
• Use of administrative data
• The AHCIP

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Canadian Community Health Survey (2000/01)

• Conducted by Statistics Canada Part of the
  National Roadmap Initiative
• Probability sample from the (eligible) national
  population Labour Force Survey Sampling frame.
• Sample size n 130,880
• Included self-reported chronic conditions,
  including MS.
• Included the CIDI Short Form for Major Depression
  (Kessler et al.)

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Depressed Mood?
End
Loss of Interest?
No
No
Yes
Yes
Loss of Interest
4 other symptoms?
End
No
No
3 other symptoms?
End
Yes
No
MDE
Yes
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Depressed Mood?
End
Loss of Interest?
No
No
Yes
Yes
Loss of Interest
4 other symptoms?
End
No
No
3 other symptoms?
End
Yes
No
MDE
Yes
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Depressed Mood?
End
Loss of Interest?
No
No
Yes
Yes
Loss of Interest
4 other symptoms?
End
No
No
3 other symptoms?
End
Yes
No
MDE
Yes
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Depressed Mood?
End
Loss of Interest?
No
No
Yes
Yes
Loss of Interest
4 other symptoms?
End
No
No
3 other symptoms?
End
Yes
No
MDE
Yes
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Epidemiology of MDE in MSCanadian Community
Health Survey

• The weighted prevalence of MS was 0.24 (95 CI
  0.20 0.28).
• There were 322 people with MS
• Data on subtype not available
• This is consistent with other Canadian estimates.

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Epidemiology of MDE in MSCanadian Community
Health Survey

• Overall Annual Prevalence - 7.4 (95 CI 7.2
  7.6).
• In women, 9.4 (95 CI 9.1 9.7)
• In men, 5.3 (95 CI 5.1 5.6).
• 18-45 years 9.0 (95 CI 8.7 9.3)
• 45 and over 5.5 (95 CI 5.2 5.7)

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Table 1. Annual Major Depression Prevalence in
CCHS Subjects with and without MS.  
weighted not including MS.        
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Table 2. Stratified Analysis, Major Depression
Prevalence in CCHS Subjects with and without MS.
 
         
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Logistic Regression Analysis

• An MS by age interaction term was not significant
  (Wald test statistic 2.40, p 0.12), so the
  model was simplified by elimination of this term.
  
• Women had higher prevalence (OR 1.9, 95 CI 1.8
  2.0)
• The younger age group had higher prevalence (OR
  for age 18-45 1.7, 95 CI 1.6 1.9)
• The adjusted odds ratio for major depression
  among persons with MS was 2.3 (95 CI 1.6 3.3).

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Limitations

• Age and duration of MS was highly correlated.
• The test for age-sex interaction may have lacked
  power

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AHCIP

• The Canadian health system works on a public
  insurance model
• ICD diagnostic codes are submitted with physician
  billings
• This administrative data can be used for
  research purposes

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MS Case Identification

• A longitudinal record covering the period 1985 to
  2002 was created.
• Cases were defined as those with two or more
  physician services for MS (ICD-9-CM 340) during
  this period.
• ICD-9CM codes for affective disorders (bipolar,
  unipolar, unspecified) were also identified.

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Results

• N2,332,418 subjects identified, aged 15 and
  over.
• There were 8,999 persons with MS, a prevalence of
  386 per 100,000 (95 CI 377 394).
• The sample included 178,612 subjects with an
  affective disorder, leading to a prevalence of
  7.7.

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Affective Disorder Prevalence, by Age Group and
MS Status
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Relative Prevalence for Affective Disorders and
MS, by Age Group Sex

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Table 1. Logistic Regression Analysis
all p-values testing the null hypothesis of
OR1 are lt 0.002. this age group was treated
as the baseline group for age.
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Conclusions

• The association between MS and major depression
  is real and not due to selection bias.
• The strength of association between MS and major
  depression is stronger than that of chronic
  conditions generally.

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Conclusions

• There is no single strength of association
  between major depression and MS.
• MS is more strongly associated with affective
  disorders in men than women
• MS is more strongly associated with affective
  disorders in young people
• The burden of major depression in MS appears to
  be greater in women, however.

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