At least 11 people have died over the past six years because they were apparently unable to receive prompt medical attention after having surrendered their national health insurance cards for nonpayment of fees, according to a Kyodo News survey compiled Wednesday.

As most of the patients who died were low-income earners, their cases provide a window into the disparities of Japanese society, where a universal health-care system is supposed to cover everyone.

The number of households that fail to pay national health insurance fees is on the rise, with about 1.3 million having surrendered their insurance cards as of June 2004.