Consumer prices in the metropolitan area rose modestly last month compared with a year ago on higher residential rents.

The federal Bureau of Labor Statistics reported Tuesday that its consumer price index for the 31-county region that includes Long Island climbed 1 percent in September compared with a year earlier.

Year-over-year changes in the index have been 1 percent or less since April, according to Martin Kohli, the bureau’s chief regional economist.

In September, residential rents increased 2.9 percent compared with a year ago.

The cost of medical care was up 5.8 percent year over year.

Offsetting these increases somewhat were lower prices for energy and groceries.

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The cost of gasoline fell 6.8 percent between last month and September 2015. Electricity was down 3/10ths of 1 percent in the same period while natural gas was up 4/10ths of 1 percent.

Grocery prices declined 2.4 percent in September compared with a year ago. However, restaurant meals cost 3.2 percent more than in 2015.

The bureau also announced a slight downward revision of the index’s June increase, from 1 percent to 9/10ths of 1 percent, because of incorrect prices for prescription drugs from May through August.

Kohli said Tuesday it was the first time in his 25 years at the bureau that the metro-area index had to be revised.