WASHINGTON (Reuters) - Twenty percent of Americans say they have delayed or postponed medical care, mostly doctor visits, and many said cost was the main reason, according to a survey released on Monday.

The Thomson Reuters survey found 21 percent of U.S. adults expected to have difficulty paying for health insurance or healthcare services in the next three months.

"The results of this survey have serious implications for public health officials, hospital administrators, and healthcare consumers," Gary Pickens of the Healthcare division of Thomson Reuters, who led the study, said in a statement.

"We are seeing a positive correlation between Americans losing their access to employer-sponsored health insurance and deferral of healthcare."

Pickens added that "if this trend continues, it will ultimately have an impact on our collective well-being."

Thomson Reuters Healthcare is part of

the same company as the Reuters news agency.

Pickens and colleagues surveyed 12,000 Americans in February and March and said their findings were representative of the United States in general.

They found that 24 percent of people who canceled or postponed care said cost was the primary reason.

In 2006, the last time the question was asked on the survey, 15.9 percent of people said they had postponed or canceled medical care in the past year.

More than 54 percent who skipped care said they missed a doctor visit. Eight percent said they delayed or skipped medical imaging of some sort.

Pickens and colleagues found the percentage of households with employer-sponsored insurance declined to 54.6 percent in 2009 from 59 percent in early 2008. The percentage of adults covered by Medicaid, the state-federal health insurance plan for the poor, rose to 14.5 percent in 2009 from 11.9 percent in 2008.