Tens of thousands of uninsured patients could qualify for up to $3.5 million in refunds on payments they made to eight Chicago and suburban hospitals under a class-action lawsuit settlement approved by a Cook County judge. Judge Sophia Hall accepted the settlement between patients and Oak Brook-based Advocate Health Care, the largest provider of medical care in the Chicago area. Advocate previously sent notices to 170,000 former patients about the settlement. Now it will mail claim forms to 40,000 of those patients it has determined are likely to be eligible, said an Advocate spokeswoman.