Table 1

Attributes of combined case-control studies

References of studies
Ref. 15Ref. 18Ref. 22
Cases (n)408362290
Controls (n)1021686645
Period of selection1972–19781978–19791982–1984
Age range (years)20–9524–8540–62
SiteBostonBoston and Livingston, NJQuebec City, Quebec Canada