depending on the context, "hospitalisation" does not always means inpatient. It is more a description of the state of the paperwork, a patient is registered as "hospitalise" in order to be covered financially but the procedure can done as in patient, out patient or even at home. So a generic letterhead would give the reference to an orientation office or reception.
see following example "hospitalisation a domicile":
http://www.hospitalisation-domicile-maymard.fr/