A mixed between-within subjects analysis of variance ( ANOVA ) revealed a significant interaction between time ( before and after intervention ) and group ( PR vs. CPT ) on fibrinogen levels ( F ( 1 , 22 ) = 0.57 , p < 0.0001 ) and a significant main effect of time ( F ( 1 , 22 ) = 0.68 , p = 0.004 ) .