For having PSA tests alone, the factors with the largest independent effects were age (60–69 vs 50–59 years; OR = 1.80, 95% CI 1.72-1.89), having a family history of prostate cancer (OR = 1.64, 95% CI 1.54-1.75), having private health insurance (OR = 1.60, 95% CI 1.52-1.68) and being treated by a doctor in the past month (OR = 1.49, 95% CI 1.44-1.55). This evidence concerns the gene KLK3 and prostate cancer.