Although I have treated a small number of epididymitis cases, I have no study data. I would refer you to these documents as a starting point only:

1: Horner PJ; European Branch of the International Union against Sexually Transmitted Infection and the European Office of the World Health Organization. Related Articles, Links
European guideline for the management of epididymo-orchitis and syndromic management of acute scrotal swelling.
Int J STD AIDS. 2001 Oct;12 Suppl 3:88-93. No abstract available.
PMID: 11589805 [PubMed - indexed for MEDLINE]

2: [No authors listed] Related Articles, Links
National guideline for the management of epididymo-orchitis. Clinical Effectiveness Group (Association of Genitourinary Medicine and the Medical Society for the Study of Venereal Diseases).
Sex Transm Infect. 1999 Aug;75 Suppl 1:S51-3. No abstract available.

This link may work:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=PubMed