Part 1 | Vascular risk factors for depression and apathy 49 3 interviews and general practitioner (GP) information (as in the Netherlands all patients are linked to only 1 GP, who receives all medical information from specialists). Previously, a LASA study showed that self-report information on stroke was reasonably moderately accurate when compared with GP information (concordance: [kappa] = 0.56; 95% confidence interval [CI] 0.48-0.64) and that concordance did not covary with level of depressive symptoms of patients 17. We considered a stroke to have occurred if selfreported and GP information was consistent or if a medical specialist had confirmed the GP diagnosis of stroke. Fatal stroke was defined as ICD-9 codes 431, 433, 434, and 436 and ICD-10 codes I-61, I-63, and I-64 on the death certificates registered by the Netherlands Central Bureau of Statistics. These were 100% complete. The primary outcome, time to stroke, is calculated for nonfatal stroke as the time between baseline and halfway the year for which the stroke has been reported; for fatal stroke, the exact time between baseline and death. Depression Depressive symptoms were measured using the self-report Center for Epidemiologic Studies Center for Epidemiologic Studies-Depression (CES-D) scale. All 20 items refer to the past week and are scored on a 4-point scale (sum score range 0-60). The psychometric properties of the scale are good in an older population and overlap with symptoms of physical illness is minimal 18. A score of >=16 indicates clinically relevant depressive symptoms 19. In LASA, the cutoff of 16 or higher had a sensitivity of 100% and a specificity of 88% for major depressive disorder according to DSM-IV criteria 19. Neuroticism Neuroticism is a personality trait that is stable across the lifespan and not affected by physical health status 20. People with a high level of neuroticism are sensitive to negative stimuli 21, causing emotional instability and negative moods like anxiety, sadness, guilt, hostility, and self-dissatisfaction 20 22. Neuroticism was measured using the Dutch Personality Questionnaire (DPQ) 23. Pilot studies before LASA started showed that the original scale of 36 items could be abbreviated without loss of validity or reliability 24 25. These DPQ items have strong negative relations with the Emotional Stability Scale of the NEO Personality Inventory-Revised 23. The DPQ asks respondents if statements apply to them; possible answers are yes/do not know/no. Scores range between 0 and 50. Cardiac disease As previously described 4: “Cardiac disease was defined as myocardial infarction, congestive heart failure, angina pectoris, or cardiac arrhythmia and established at baseline using an algorithm used earlier in LASA 26. This algorithm uses 3 sources of information: selfreported, medication, and GP information. We considered only 1 confirmative source necessary for diagnosis because self-reported cardiac disease is sufficiently accurate in LASA (concordance with GP: [kappa] = 0.69; 95% CI 0.65-0.73).” 17
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