Steward Health Care Network, the second largest physician network in Massachusetts, will offer Quartet Health's platform as a service to its providers and their patients.

The multi-year agreement expands the partnership between Steward and Quartet Health that started in 2015.

Boston-based Steward Health Care, a Next Generation ACO,  is the largest integrated community care organization and hospital network in New England, with more than 17,000 employees in more than 150 communities.

[Also: Steward Healthcare: ACO success hinges on IT strength]

Former Rhode Island Congressman Patrick Kennedy joined the board of the New York-based startup last October.

Kennedy has been open about his addictions to alcohol and prescription drugs, and he recently wrote about his struggles – and those of his family – in his book, A Common Struggle: A Personal Journey Through the Past and Future of Mental Illness and Addiction.

While serving in Congress, Kennedy authored the Mental Health Parity Act, which required health insurance companies to provide coverage benefits for treatment of mental health conditions that are comparable to coverage provided for physical conditions.

Quartet estimates that 7 to 9 percent of Massachusetts residents are treated for both a chronic medical condition and behavioral health condition in a given year.

[Also: Legislation seeks to extend meaningful use incentives to behavioral health]

Also, an additional 20 percent of this population is either not diagnosed or not treated for behavioral health conditions.

As Quartet executives put it, care is often disjointed.

Quartet's technology platform identifies individuals in need of behavioral health resources and enables primary care providers to set those individuals on effective treatment paths in tight collaboration with behavioral health professionals. To date, more than 70 percent of Steward providers who used the Quartet platform for the first time became repeat users.

Under the expanded agreement with Quartet, all Steward primary care providers will be able to use the Quartet platform and all Steward patients will be able to access free tools and services including online self-care resources, peer support interventions and telepsychiatry.

"Access to behavioral health resources is one of the most pressing challenges in primary care today," Steve Stein, MD, said in a statement. Stein is part of Family Medical Associates, a practice within the Steward Health Care Network.

Besides Kennedy, Quartet is backed by Annie Lamont from Oak and Carl Byers from Fidelity Bio.

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