of interview) were used in calculating hazard ratios. Basic univariate analyses were conducted with PASW Statistics Software, Release 18.0.0 (IBM-PASW, 2009). Advanced analyses were conducted with STATA, version 8.2 (StataCorp, 2001). Standard deviations of means and confidence intervals for advanced Cox regression models were adjusted for family clustering using Huber-White robust standard errors. The Efron approximation (Hosmer & Lemeshow, 1989) was used to handle ties. Missing data were deleted listwise in Cox regression analyses.
