Referrals increase. Why?

Barnett and colleagues report that the number of referrals from ambulatory visits have grown 94% from 1999 to 2009. (Arch Intern Med. 2012;172(2):163-170) Surprised? I am not. 
They analyzed 845,243 ambulatory visits and estimated that a visit to a physician generated an increase in referral to another physician from 4.8% to 9.3% in the ten years. A somewhat slower referral pattern was found in physicians groups that had an ownership stake in the practice or those with the majority of income from managed care contracts. In the same time period, the “total number of ambulatory visits in the United States increased from 841 million to 1130 million per year or 3040 to 3720 visits per 1000 persons annually.” Both PCP’s and Specialists showed an increase in referral rates. Specialists referrals increased primarily in ENT, GI and Orthopedics same as for PCP’s. It is clear that further specialization has left some PCP’s uncomfortable with the rapid increase in new knowledge. But, an important factor is that they are burdened with more complicated patients and less time to deal with them. 
Comment: No one knows what the proper referral rate is and so we cannot judge whether these findings have any meaning with regard to appropriateness. PCP’s in managed care contracts tend to refer less is nothing new. We found that out in the managed care era. How will the reform and ACO’s deal with referrals?