Bad debt expense as a percent of revenues was 7.9 percent, an increase of 20 basis points compared to 7.7 percent in the fourth quarter of 2011. The increase in bad debt expense was largely the result of the increase in uninsured patient volumes. Our self-pay collection rate was 28.9 percent in the fourth quarter of 2012, a 120 basis point improvement compared to 27.7 percent in the fourth quarter of 2011.
Net operating revenues were $2.331 billion, an increase of $159 million, or 7.3 percent, compared to net operating revenues of $2.172 billion in the fourth quarter of 2011. Commercial managed care revenue increased 5.2 percent, which reflected a 7.1 percent and 7.6 percent increase in commercial managed care revenue per patient day and per outpatient visit, respectively.
Total net patient revenue per adjusted admission was $11,866, an increase of 2.8 percent. This pricing increase primarily reflects improved terms in our contracts with commercial managed care payers, as well as higher Medicare reimbursement rates that became effective on October 1, partially offset by a softer payer mix.
Selected operating expenses of our hospital operations, defined as the sum of salaries, wages and benefits, supplies and other operating expenses excluding the Company’s Conifer services business, increased by only 1.9 percent on a per adjusted admission basis. This cost metric excludes Conifer since Conifer does not generate incremental volumes, which impacts the relationship of this aggregate cost metric to patient volumes. Supplies expense per adjusted admission declined 1.1 percent. Electronic health record incentives were $27 million in the fourth quarter of 2012 compared to $5 million in the fourth quarter of 2011 and are not a part of the definition of selected operating expenses.Cash and cash equivalents were $364 million at December 31, 2012 compared to $83 million at September 30, 2012. The Company had no outstanding balance on its bank line at December 31, 2012. Accounts receivable days improved by two days to 53 days down from 55 days at September 30, 2012. Approximately $57 million of aggregate revenues related to the California Provider Fee program and the Texas uncompensated care 1115 waiver program were recognized in Adjusted EBITDA in 2012, but were not yet received by year end.