Multivariable regression analysis of dependent variable (Y) on independent variable (X).

Columns include adjusting variables (in addition to age and sex), parameter or slope estimate (ß), standard error (SE), and P value (test of slope = 0) for analyses done within stone former and control groups, Also given is the P value for the interaction term (test for common slopes) between X and stone group from similar models pooling stone-formers and controls. CSF = confirmed Ca stone formers; TSF = total stone formers (confirmed plus presumed).