borderline significanceP = 0.036
However this result is limited by a low case number in each subgroup and showed a borderline significance: low risk subgroup P = 0.036, HR = 7.308, CI 95 1.168–45.703; other than low risk subgroup P = 0.027, HR = 7.442, CI 95 1.677–33.028, importantly due to multiple testing (k = 2) a P -value <0.025 is considered as statistically significant, Fig. 2a .