Table 2

Characteristics of included studies: cohort studies

Study, yearCountryPopulationMean age, yearsnDiagnosis of depressionCategories of vitamin D, nmol/lMeasurement of vitamin DLoss to follow-up, %Length of follow-up, years
Chan (2011)10ChinaMen aged >65 years72.5801Score 8 on GDSQuartiles (<63, 64–76, 77–91, >92) and categories (<50, 50–74, 75–99, >100)RIA214
May (2010)9USACardiovascular patients aged ≥50 years73.17358Clinical diagnosisCategories (<37.5, 37.5–75, 75–125, >125CIANRa1b
Milaneschi (2010)39ItalyMen and women aged ≥65 years74.4656Score ≥16 on CES-DTertiles (<31.7, 31.7–53.9, >53.9) and cut-off point (<50 or ≥50)RIA36
Total cohort studies8815

CIA, chemiluminescent immunoassay; CES-D, Center for Epidemiological Studies – Depression scale; GDS, Geriatric Depression Scale; NR, not reported; RIA, radioimmunoassay.

  • a Most of cohort (71%) ‘not evaluable’ at 500 days.

  • b Mean follow-up period.