A large health insurer is hiring another company to manage chiropractic benefits in a key market.

Aetna Inc., Hartford, will be relying on American Specialty Health Inc., San Diego, to administer chiropractic benefits for Aetna health maintenance organization members in Delaware, Pennsylvania, Virginia and the District of Columbia.

The deal increased the size of Aetna’s chiropractic network in that region to about 1,500 providers, from 1,300, according to Aetna.

Aetna has about 800,000 HMO members in the region entrusted to American Specialty.