Do Chinese hospital services constitute an oligopoly? Evidence of the rich-club phenomenon in a patient referral network

Research on medical practice that uses big data has attracted considerable attention recently. In this paper, we focused on a large set of patient referral data gathered in Fujian province, China, between 2009 and 2011. We built a directed weighted patient referral network. By using four metrics from network science, namely, the power-law distribution, global rich-club coefficient, local rich-club coefficient, and assortativity coefficient, we identified a significant rich-club phenomenon in this network. In addition, the community detection was also carried out to find the relationship between rich members and non-rich members. The findings indicate an oligopoly in which Class-III hospitals occupy an overwhelmingly dominant position over the competition. Also, the characteristic ‘significant regional clustering’ was inferred from the results.