An increase in disability insurance claims and a decrease in health plan enrollment contributed to a drop in profits at CIGNA Corp. during the fourth quarter of 2005.

CIGNA, Philadelphia, is reporting $224 million in net income for the latest quarter on $4.2 billion in revenue, compared with $558 million in net income on $4.3 billion in revenue for the fourth quarter of 2004.

The managed care company ended the quarter providing or administering health coverage for 9.1 million people, down from 9.7 million people a year earlier.

Health plan membership seems to be stabilizing, but health and disability operating costs were up, CIGNA says.

CIGNA notes that the net income figure it reported for the fourth quarter of 2004 included $169 million in gains and benefits from tax and accounting adjustments.