Describing this as "a serious development" with implications for patient care and safety, he added: "It is also a very visible sign that individual patients, individual customers do not have bargaining power to stop insurance companies from such practices. When an insurance company moves the goalposts for an Integrated Shield Plan, it is not so easy for a patient to switch provider, because existing conditions become pre-existing conditions under the new policy."

He called for the authorities to step in. "The invisible hand of the market appears to have become unbalanced. And so I call upon MOH and MAS to look into this and see if the visible hand of the regulators needs to come in to level the playing field for patients," he said. The two agencies are the Ministry of Health (MOH) and Monetary Authority of Singapore (MAS), which regulates financial services including insurance.