An average of one patient per day receives the wrong medication at each hospital in the Tokyo metropolitan area, and nurses are generally held accountable for the errors, according to a survey released by the Japanese Nursing Association.

The internal survey, which was released Saturday, examined 11 hospitals in the metropolitan area for a one-month period in February. The hospitals each had 684 beds and 490 nurses on average.

The survey protected the anonymity of the participating nurses to encourage accuracy, according to the association. It cited 257 cases in which patients were given the wrong drugs, mostly by nurses.