Depression and mortality: artifact of measurement and analysis?
BACKGROUND
Previous research demonstrates various associations between depression, cardiovascular disease (CVD) incidence and mortality, possibly as a result of the different methodologies used to measure depression and analyse relationships. This analysis investigated the association between depression, CVD incidence (CVDI) and mortality from CVD (MCVD), smoking related conditions (MSRC), and all causes (MALL), in a sample data set, where depression was measured using items from a validated questionnaire and using items derived from the factor analysis of a larger questionnaire, and analyses were conducted based on continuous data and grouped data.


METHODS
Data from the PRIME Study (N=9798 men) on depression and 10-year CVD incidence and mortality were analysed using Cox proportional hazards models.


RESULTS
Using continuous data, both measures of depression resulted in the emergence of positive associations between depression and mortality (MCVD, MSRC, MALL). Using grouped data, however, associations between a validated measure of depression and MCVD, and between a measure of depression derived from factor analysis and all measures of mortality were lost.


CONCLUSIONS
Low levels of depression, low numbers of individuals with high depression and low numbers of outcome events may limit these analyses, but levels are usual for the population studied.


CONCLUSIONS
These data demonstrate a possible association between depression and mortality but detecting this association is dependent on the measurement used and method of analysis. Different findings based on methodology present clear problems for the elucidation and determination of relationships. The differences here argue for the use of validated scales where possible and suggest against over-reduction via factor analysis and grouping.
Psychology, DEC, Bournemouth University, Dorset BH12 5BB, United Kingdom. Electronic address: k.appleton@bournemouth.ac.uk.
K M
KM
Appleton
School of Medicine, Dentistry and BioMedical Sciences, Queen's University Belfast, Belfast BT12 6BJ, United Kingdom.
J V
JV
Woodside
The Strasbourg MONICA Project, Department of Epidemiology and Public Health, EA 3430, University of Strasbourg, Strasbourg, France.
D
D
Arveiler
The Strasbourg MONICA Project, Department of Epidemiology and Public Health, EA 3430, University of Strasbourg, Strasbourg, France.
B
B
Haas
The Lille Monica Project, INSERM U744, Lille, France.
P
P
Amouyel
The Lille Monica Project, INSERM U744, Lille, France.
M
M
Montaye
The Toulouse MONICA Project, INSERM U558, Toulouse, France.
J
J
Ferrieres
The Toulouse MONICA Project, INSERM U558, Toulouse, France.
J B
JB
Ruidavets
School of Medicine, Dentistry and BioMedical Sciences, Queen's University Belfast, Belfast BT12 6BJ, United Kingdom.
J W G
JWG
Yarnell
School of Medicine, Dentistry and BioMedical Sciences, Queen's University Belfast, Belfast BT12 6BJ, United Kingdom.
F
F
Kee
School of Medicine, Dentistry and BioMedical Sciences, Queen's University Belfast, Belfast BT12 6BJ, United Kingdom.
A
A
Evans
The Coordinating Center, INSERM U780, Hôpital Paul Brousse, Villejuif, France.
A
A
Bingham
The Coordinating Center, INSERM U780, Hôpital Paul Brousse, Villejuif, France.
P
P
Ducimetiere
School of Medicine, Dentistry and BioMedical Sciences, Queen's University Belfast, Belfast BT12 6BJ, United Kingdom.
C C
CC
Patterson
D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000401:mortality; D003863:Depression / Q000453:epidemiology / Q000401:mortality; D003866:Depressive Disorder / Q000453:epidemiology* / Q000401:mortality; D005163:Factor Analysis, Statistical; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009660:Northern Ireland / Q000453:epidemiology; D016016:Proportional Hazards Models; D012907:Smoking / Q000401:mortality; D011795:Surveys and Questionnaires; D014029:Tobacco Use Disorder / Q000453:epidemiology* / Q000401:mortality
Cardiovascular disease; Depression; Methodology; Mortality; Questionnaires; Statistical analysis