Table 2.

Stratified summary ORs and corresponding 95% CIs for the association between selenium concentrations and bladder cancer risk (random effects model)

OR (95% CI)I2 (P)Publication bias* (P)
ReferenceExposed
Sex
    Men (n = 4)10.95 (0.69-1.27)16.2% (0.311)−1.56 (0.314)
    Women (n = 2)10.55 (0.32-0.95)23.7% (0.252)
Sample specimen
    Toenails (n = 4)10.81 (0.66-1.00)0.0% (0.617)−0.38 (0.751)
    Serum (n = 3)10.33 (0.21-0.51)0.0% (0.728)0.77 (0.576)
Smoking status§
    Never (n = 2)10.89 (0.55-1.44)0.0% (0.333)
    Ever (n = 3)10.85 (0.54-1.34)0.0% (0.861)−1.84 (0.507)
Study design
    Case-control (n = 3)10.53 (0.23-1.20)84.8% (0.001)−3.07 (0.518)
    Nested case-control (n = 3)10.70 (0.40-1.21)6.2% (0.344)−2.62 (0.323)
    Case-cohort (n = 1)10.67 (0.47-0.96)

NOTE: n, number of studies considered; I2, degree of heterogeneity.

  • *Coefficient from Egger's test for publication bias.

  • Top category of exposure to selenium presented in each study, according to each stratum of sex, matrix, smoking status, and study design.

  • Studies with specific data for men: Nomura et al., 1987; Michaud et al., 2002, Michaud et al., 2005; and Wallace et al., 2009; studies with specific data for women: Michaud et al., 2005 and Wallace et al., 2009.

  • §Studies with specific data for never smokers: Zeegers et al., 2002 and Wallace et al., 2009; studies with specific data for ever smokers: Michaud et al., 2002; Zeegers et al., 2002; and Wallace et al., 2009.