A brain and heart hospital and research centre in Japan has found 158 cases of studies being done in violation of ethics standards since 2013.

Hisao Ogawa, the president of the National Cerebral and Cardiovascular Center (NCVC) in Suita, apologized to the people affected and their families at a press conference on 30 May.

An internal investigation found that researchers involved in two cardiac studies said that the research had been approved by an ethics review board when it had not, the NCVC said in a statement. According to the daily newspaper Mainichi Shimbun, the researchers told the investigators that they had thought that approval for previous research also applied to those studies.

In a further 156 cases, participants weren’t given the option to opt out of a﻿ study once they had left hospital. In some of these cases, researchers had wrongly assumed that administrative staff would inform the participants of the procedures to opt out by post or through the institute’s website.

The NCVC said that the authors of two papers that resulted from the cardiac studies without ethics approval would be seeking retractions.

The institute will also commission an independent investigation and consider disciplinary action, it said in its statement.