Dive Brief:

• A Massachusetts provider coalition wrote to the state Attorney General's office citing "grave concerns" about an agreement allowing Boston-based Partners HealthCare to acquire at least three more hospitals in the state. Partners is the state's largest hospital and physicians network that includes Massachusetts General and Brigham & Women's. The coalition warned that Partners' growth could raise costs and possibly lead to some hospital closures. 
• One rival hospital CEO said Partners' planned expansion “takes an organization that’s already three times larger than everyone else and makes it four times larger."
• The opposition group is being led by executives from Tufts Medical Center, Beth Israel Deaconess Medical Center, Lahey Health and Atrius Health. This represents the competing providers' first public challenge of an agreement in principle between Partners and the AG's office. It effectively ends a five year federal-state antitrust investigation into Partners' market dominance and contracting practices. Rivals want the deal open to public scrutiny before it goes to a Superior Court judge for final approval.

Dive Insight:

Under the agreement in principle, Partners would complete its takeover of three hospitals and add at least 550 doctors. Partners can't increase prices at its hospitals or provider groups above inflation for the next 6 1/2 years and is restricted from further growth for 5 to 10 years. 

But will these measures help control costs by restraining Partners' market power? Its rivals think not. They assert it could lock in Partners' already-existing advantages. The state AG's office and Partners insist the process is transparent, but competitors say the public hasn't heard much as final terms are negotiated.

In general, industry experts say basic antitrust issues are familiar and not complex: It all boils down to a question of where to draw the line. Partners' competitors want the line drawn in full public view.