Table 14.

Top 10 important features for death1yr and PCI generated by Random Forest feature selection method (Genuer et al. 2010)

Rank	Death1yr	PCI
1	Total RVU of the referral path	Average time gap on the referral path
2	Total RVU of the previous referral path	Indicator of patient’s age in 66-70
3	Average time gap on the referral path	Average PageRank values of all physicians on the referral path
4	Time range of the referral path	Indicator of the key physician’s specialty on the referral path as “interventional cardiology”
5	Average index of the first-time occurrence on a referral path for the last physician	Indicator of patient’s age in 76+
6	Local clustering coefficient of the last physician on the referral path	The number of referral paths that include the last physician
7	Times of being the end node on a referral path of the last physician on the referral path	Indicator of the key physician’s specialty on the referral path as “interventional cardiology”
8	Times of being the first node on a referral path for the last physician	Average #involved paths among physicians on the referral path
9	indicator of patient’s age in 76+	Average times of being the first node on a referral path for all physicians on the referral path
10	Average times of being the end node on a referral path for all physicians on the referral path	Times of being the first node on a referral path for the last physician