In the fourth quarter, revenue totaled $4.1 billion, adjusted earnings per share reached $6.77, and free cash flow was $548 million.
For the full year, revenue was $16.1 billion, adjusted earnings per share totaled $28.52, and free cash flow reached $2.6 billion.
Our base business continued its progress during the quarter, with diagnostics and drug development revenue growing 8.8% and 8.2%, respectively.
drug development ended the year with a solid trailing 12-month net book-to-bill of 1.25 and a strong backlog of $15 billion, representing a $579 million increase in the third quarter.
Also decentralized clinical trial awards were up 62% over the prior year.
We have performed over 74 million tests for COVID to date, of which approximately 8.6 million were in the fourth quarter.
The company's COVID-related innovations in the quarter included the rollout of observed self-collection for COVID PCR testing at over 1,000 patient service centers.
Through our new long-term relationship with Ascension, we will manage its hospital-based laboratories in 10 states, and we will purchase select assets of its outreach laboratory business for approximately $400 million.
We expect the first year annualized revenues to be between $550 million and $600 million from the combined hospital business and lab asset acquisition.
The transaction is expected to be accretive to our earnings and cash flow in year 1 and should return its cost of capital by year 2.
Among them are the initiation of a dividend starting in the second quarter of 2022 as well as a $2.5 billion share repurchase program, $1 billion of which is being repurchased on an accelerated basis.
We are also implementing a new LaunchPad business process improvement initiative that targets $350 million in savings over the next three years.
Revenue for the quarter was $4.1 billion, a decrease of 9.7% compared to last year due to declines in organic revenue of 10.3% and divestitures of 0.1%, partially offset by acquisitions of 0.6% and favorable foreign currency translation of 10 basis points.
The 10.3% decline in organic revenue was driven by a 15.3% decrease in COVID testing, partially offset by a 5% increase in the company's organic base business.
Operating income for the quarter was $731 million or 18% of revenue.
During the quarter, we had $93 million of amortization and $79 million of restructuring charges and special items.
Excluding these items, adjusted operating income in the quarter was $902 million or 22.2% of revenue compared to $1.4 billion or 31.8% last year.
The tax rate for the quarter was 19.3%.
The adjusted tax rate excluding restructuring charges, special items and amortization, was 24.6% compared to 24.8% last year.
Going forward, we continue to expect the adjusted tax rate to be approximately 25% excluding any impact from potential tax reform.
Net earnings for the quarter were $553 million or $5.75 per diluted share.
Adjusted earnings per share which exclude amortization, restructuring charges and special items, were $6.77 in the quarter, down from $10.56 last year.
Operating cash flow was $698 million in the quarter compared to $775 million a year ago.
Capital expenditures totaled $150 million compared to $99 million last year.
And as a result, free cash flow was $548 million in the quarter compared to $675 million last year.
During the quarter, we used $1 billion of our cash flow for our accelerated share repurchase program and invested $171 million on acquisitions.
Revenue for the quarter was $2.6 billion, a decrease of 16.9% compared to last year due to organic revenue being down 17.8%, partially offset by acquisitions of 0.7% and favorable foreign currency translation of 20 basis points.
The decrease in organic revenue was due to a 21.8% reduction from COVID testing partially offset by a 4.1% increase in the base business.
Relative to the fourth quarter of 2019, the compound annual growth rate for the base business revenue was 5% primarily due to organic growth.
Total volume decreased 8.7% compared to last year as organic volume decreased by 8.9% partially offset by acquisition volume of 0.3%.
The decrease in organic volume was due to a 14.6% decline in COVID testing partially offset by a 5.7% increase in the base business.
Price mix decreased 8.2% versus last year due to lower COVID testing of 7.2% and lower base business of 1.6% partially offset by acquisitions of 0.5% and currency of 0.2%.
Diagnostics organic base business revenue growth was 7.2% compared to its base business last year, with 8.1% coming from volume, partially offset by a 1% decline from price mix.
diagnostics adjusted operating income for the quarter was $776 million or 29.6% of revenue compared to $1.2 billion or 39.1% last year.
COVID testing margins were down compared to last year primarily due to a volume decline of approximately 50%, while the company continued to maintain capacity.
diagnostics achieved its goal to deliver approximately $200 million of net savings from its three-year LaunchPad initiative.
Revenue for the quarter was $1.5 billion, an increase of 3.9% compared to last year due to organic base business growth of 7.9% and acquisitions of 0.3%, partially offset by lower COVID testing performed through its centralized business of 4% and divestitures of 0.3%.
Relative to the fourth quarter of 2019, the compound annual growth rate for base business revenue was 9.9% primarily driven by organic growth.
Adjusted operating income for the segment was $206 million or 14.2% of revenue compared to $248 million or 17.8% last year.
We continue to exclude the enterprise component of drug development bonus expense which is reflected in corporate unallocated and totaled $11 million for the quarter.
For the trailing 12 months, net orders and net book-to-bill remained strong at $7.3 billion and 1.25, respectively.
Backlog at the end of the quarter was $15 billion, an increase of 8.7% compared to last year.
And we expect approximately $5 billion of this backlog to convert into revenue over the next 12 months.
This guidance range includes the expectation that the base business will grow seven and a half to 10%, while COVID testing is expected to decline 60% to 75%.
We expect diagnostics revenue to decline 11 and a half to 17 and a half percent compared to 2021.
This guidance range includes the expectation that the base business will growth three and a half to 6%.
COVID testing revenue is expected to decline 60% to 75%.
At the midpoint of our base business guidance range, the compound annual growth rate compared to 2019 would be 4.4% primarily driven by organic growth in both volume and price mix.
We expect drug development revenue to grow 7% to 9.5% compared to 2021.
This guidance includes the negative impact from foreign currency translation of 40 basis points.
This guidance range also includes the expectation that the base business will grow seven and a half to 10% compared to 2021.
At the midpoint of our base business guidance range, the compound annual growth rate compared to 2019 would be 11.3%.
Our adjusted earnings per share guidance is $17.25 to $21.25 compared to 2021 adjusted earnings per share of $28.52.
Free cash flow is expected to be between $1.7 billion to $1.9 billion compared to $2.6 billion in 2021.
We expect enterprise base business organic revenue to grow at a compound annual growth rate of 4% to 7% compared to 2021.
We also expect revenue growth from acquisitions to represent additional annual growth of 2% to 3%.
We expect drug development base business organic revenue to grow at a 7% to 10% CAGR compared to 2021.
As we continue to emphasize profitable growth, we expect enterprise margin expansion of 30 to 50 basis points on average annually through the outlook period compared to 2021 which was approximately 14 and a half percent.
This margin expansion is due in part to the company's LaunchPad initiative which is expected to deliver $350 million of cost savings over the time period to help offset inflationary costs.
And finally, we expect adjusted earnings per share to grow at an 11% to 14% CAGR compared to 2020 -- '19 adjusted earnings per share of $11.32.

Summary:
In the fourth quarter, revenue totaled $4.1 billion, adjusted earnings per share reached $6.77, and free cash flow was $548 million.
Revenue for the quarter was $4.1 billion, a decrease of 9.7% compared to last year due to declines in organic revenue of 10.3% and divestitures of 0.1%, partially offset by acquisitions of 0.6% and favorable foreign currency translation of 10 basis points.
Net earnings for the quarter were $553 million or $5.75 per diluted share.
Adjusted earnings per share which exclude amortization, restructuring charges and special items, were $6.77 in the quarter, down from $10.56 last year.
The decrease in organic revenue was due to a 21.8% reduction from COVID testing partially offset by a 4.1% increase in the base business.
Revenue for the quarter was $1.5 billion, an increase of 3.9% compared to last year due to organic base business growth of 7.9% and acquisitions of 0.3%, partially offset by lower COVID testing performed through its centralized business of 4% and divestitures of 0.3%.
We expect drug development revenue to grow 7% to 9.5% compared to 2021.
Free cash flow is expected to be between $1.7 billion to $1.9 billion compared to $2.6 billion in 2021.
We expect enterprise base business organic revenue to grow at a compound annual growth rate of 4% to 7% compared to 2021.
As we continue to emphasize profitable growth, we expect enterprise margin expansion of 30 to 50 basis points on average annually through the outlook period compared to 2021 which was approximately 14 and a half percent.
And finally, we expect adjusted earnings per share to grow at an 11% to 14% CAGR compared to 2020 -- '19 adjusted earnings per share of $11.32.