Exploring sex as a moderator of other prognostic variables in whiplash associated disorder: An observational study.

From analysis 1, both NDI (R2 = 8.7%, p < 0.01) and NPRS (R2 = 5.7%, p = 0.02) collected at baseline predicted significant variance in NDI score at 52-weeks. The interaction term of sex x z-NPRS was also significant (R2 = 3.8%, p = 0.04). In analysis 2 the regression models when disaggregated by sex showed that baseline NDI was the significant predictor of 52-week outcome in males (R2 = 22.4%, p = 0.02) while it was the NPRS as the significant predictor in females (R2 = 10.5%, p < 0.01).