KNOW ALL MEN BY THESE PRESENTS, that the person whose signature appears below
hereby constitutes and appoints Daniel H. Orenstein, Christopher H. Martin,
Emily Keith, and Paul R. Rosie and any one of them acting singly, the true and
lawful attorneys-in-fact and agents, with full power of substitution and
resubstitution, for the undersigned and in the undersigned's name, place and
stead, in any and all capacities (until revoked in writing) to sign any Form ID
or any and all instruments, certificates and documents required to be executed
on behalf of the undersigned as an individual or on behalf of the undersigned's
holding company or partnership, as the case may be, pursuant to sections 13 and
16 of the Securities Exchange Act of 1934, as amended ("the Exchange Act"), and
any and all regulations promulgated thereunder, and to file the same, with all
exhibits thereto, and any other documents in connection therewith, with the
Securities and Exchange Commission, and with any other entity when and if such
is mandated by the Exchange Act or by the By-laws of the National Association of
Securities Dealers, granting unto said attorneys-in-fact and agents full power
and authority to do and perform each and every act and thing requisite and
necessary fully to all intents and purposes as the undersigned might or could do
in person thereby ratifying and confirming all that said attorneys-in-fact and
agents, or their substitute or substitutes, may lawfully do or cause to be done
by virtue hereof.

IN WITNESS WHEREOF, this Power of Attorney has been signed as of the 11th day of
August, 2009.


/s/ Dawn Griffiths
Dawn Griffiths