We're a PCP clinic and have discharged patients from care for a variety of reasons over the years. There haven't been any problems with it, but we're very careful to maintain documentation of events that led up to the firing (drug seeking, violation of narcotic contracts, abusive & threatening behavior, and chronic no-show for appointments.) Our treatment period is normally 30 days depending on the reason for the discharge. Even if we send someone to collections (resulting in a dismissal) the letters emphasize our assumption they are withdrawing care by refusing to pay their bill or respond to our calls etc.
