| Study | Reason for exclusion |
|---|---|
| Goadsby 1994 | Not original research. Uses in its analysis the data from Ekbom 1991 and Ekbom 1993 |
| Hardebo 1998 | Open study, not double blinded |
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.