There is no effect on healthcare. When an inmate is tested, it is because their is probable cause or suspicion of use of drugs. When you are a trustee that can work outside the prison or on work release that is one of the conditions. When tested and are positive you will lose privileges and offered drug counseling. The nursing department only becomes involved when the inmate needs medical attention for withdrawal then there will be something written in the chart, possibly refered to the Physc Dr.
Drug testing on prison inmates in my opinion, does not in any way affect the laws of healthcare except that it is in line with them. This is because it is a way of ensuring that prison inmates are of the best health possible despite being in prison. It ensures that the inmates get proper counseling on drugs and how to handle withdrawal.