In eight of the 17 comparisons, however, the Cox adjusted hazard ratios differed significantly from the trial hazard ratios, suggesting the presence of unmeasured confounding. In seven of these eight instances the PERR adjusted hazard ratios differed significantly from the Cox adjusted hazard ratios, and either did not differ significantly (five outcomes) or were more similar (two outcomes) to the trial hazard ratio. In the other outcome the PERR hazard ratio was more similar to the trial but did not differ significantly from the Cox adjusted hazard ratio. A Wilcoxon signed rank test
showed that when the Cox adjusted hazard ratio differed significantly from the trial hazard ratio (n=8), the PERR adjusted hazard ratio was significantly (P