Consumer confidence in the United States last week fell to its lowest level since August, Bloomberg reports.

The Bloomberg Consumer Comfort Index dropped to minus 48.9 in the period that ended March 20 from minus 48.5 the prior week. The measure of the current state of the economy fell to a 15-month low.

The report showed that confidence among households with annual incomes exceeding $50,000 declined to its lowest level since March 2010, representing a risk to consumer spending, the largest part of the U.S. economy.

The highest gasoline prices in more than two years weighed on families.

“Households continue to operate under duress,” said John Herrmann, senior fixed-income strategist at State Street Global Markets LLC in Boston, in an interview with Bloomberg. “Inflation may prove both higher and more persistent than desirable” for consumers already “facing higher costs” for food and fuel, he said.

A measure of 100 indicates every survey participant had a positive response to all three survey components, while a negative 100 indicates every participant had a negative response. Survey components are views on the economy, personal finances and buying climate.