Epocrates' adjusted EBITDA, as defined in Epocrates' final prospectus filed with the Securities and Exchange Commission in connection with its recent initial public offering, and in the GAAP to non-GAAP reconciliation provided later in this release, was $7.1 million, or 23% of revenue for the fourth quarter of 2010, compared to $8.2 million, or 30% of revenue, in the same period last year. The decline in adjusted EBITDA for the quarter was primarily attributable to the ongoing investment in the development of an EHR platform.
For the year ended December 31, 2010, GAAP net income was $3.8 million, or $0.01 per diluted share, compared to $7.7 million, or $0.20 per diluted share, in 2009. The decline in net income for the year was primarily attributable to an increase in research and development investment and sales and marketing expenses related to the development of a new EHR platform and the development and launch of new products for the pharmaceutical industry.
For 2010, Epocrates' adjusted EBITDA was $16.9 million or 16% of revenue, from $21.8 million, or 23% of revenue in 2009. The decline in adjusted EBITDA for the year was primarily attributable to the ongoing investment in the development of the EHR platform.
Cash, cash equivalents and short-term investments totaled $54.7 million as of the end of the fourth quarter of 2010 and does not reflect the proceeds from the initial public offering that closed on February 7, 2011.As of December 31, 2010, Epocrates had total backlog of $86.5 million, consisting of deferred revenue of $55.0 million, along with $31.5 million of contractual backlog. Bookings were $37.0 million in the fourth quarter of 2010, a 22% increase compared to the fourth quarter of 2009, led by a 43% increase in bookings from pharmaceutical company clients. Crane concluded, "With our 2010 investments and recently completed initial public offering providing a strong foundation for growth, an expanded product portfolio and strong cash flow profile, we are poised to deliver on our growth targets and strengthen our leadership position. We see opportunities to build shareholder value by further leveraging our broad physician network, expanding our interactive services opportunities and developing an innovative EHR platform specifically targeted for solo and small physician practices. We are confident that we have the right strategic programs in place to position Epocrates for future success."