Home health and hospice provider Amedisys, which moved its executive headquarters to Nashville last year, has announced a definitive agreement to purchase Associated Home Care, a Boston-area company with 1,500 employees and 5,000 clients. Amedisys will reportedly pay $28 million for the company that generates about $40 million annually. Associated Home Care’s CEO Michael Trigilio has agreed to stay on to oversee a new division for Amedisys that will expand Associated Care’s private-duty care model nationwide. The transaction was expected to close at the beginning of this month.