The number of court-approved securities class action settlements declined in 2010, sinking to the lowest number in more than 10 years, Cornerstone Research Inc. said in an annual report released Thursday.

There were 86 court-approved settlements during 2010, a 15% decline from 2009. Since 2001, the number of cases settled peaked at 119 during 2005, according to “Securities Class Action Settlements 2010 Review and Analysis.”

Cornerstone also found that the dollar value of all 2010 settlements dropped to $3.1 billion, down 17% from 2009.

The decline likely won’t continue, however, and a difficult economy may have helped reduce the number of approved settlements in 2010, Cornerstone said.

A federal judge has refused to expand a lawsuit beyond the seven people who are suing a South Dakota urology clinic and its owners.

The plaintiffs sought to make it a class action suit representing more than 6,000 patients.

The lawsuit against Siouxland Urology Center in Dakota Dunes and doctors alleges that the former patients could have been exposed to blood-borne infections because medical equipment that was intended for single-patient use was reused at the clinic.

U.S. District Judge Karen Schreier ruled that the complaint did not meet all the requirements for class action status.

The plaintiffs, identified as Iowa residents, seek more than $5 million on allegations that include negligence, medical malpractice, and emotional distress.