For example, performance in two key elements of our growth strategy, accelerating the transition of patients to Optum-led value-based care and strong United Healthcare growth in serving Medicare Advantage consumers, are both tracking well with the expectations we shared with you at our recent investor conference.
These, and the broader performance across the enterprise, confirm our confidence in our ability to advance our stated growth strategies and to support our long-term 13% to 16% earnings per share growth rate.
Taken together, these efforts helped us add more than $30 billion in revenue for the year, about $10 billion above our initial outlook.
In sum, we enter 2022 with heightened confidence in our ability to execute upon the objectives we set forth in late November.
As an example, in '21, we incurred over $100 million in preparation expense.
Activity over the past several weeks shows primary care visits having declined about 10% and an even higher rate of decline in specialist visits.
OptumHealth's revenue per consumer grew by over 30% in '21, driven by the increasing number of our patients served under value-based arrangements.
Consistent with the expectations we shared in late November, we had a strong start to the year and continue to expect to add 500,000 new patients in accountable value-based relationships, benefiting from the groundwork laid over the past many years.
OptumInsight's earnings grew 25% in '21, with operating margins approaching 28% for the year.
We ended the year with a revenue backlog of $22.4 billion, an increase of $2.2 billion over the prior year.
OptumRx earnings grew 6% for the year, driven by the continued expansion of our pharmacy services businesses, supply chain initiatives and strong cost management activities and benefiting from strong customer retention.
Full-year revenues of $223 billion grew 11%.
Within the up to 800,000 new members we will serve in '22, about three-quarters will be in individual and group Medicare Advantage and the remainder in dual special needs plans.
Over the course of the year, we will look to continue to expand upon the nearly 8 million individuals we serve across 31 states.
We concluded '21 with commercial membership about 200,000 people ahead of the original outlook provided.
Full year '21 cash flow from operations was $22.3 billion or 1.3 times net income, about $2 billion above the initial outlook we shared a year ago.
We continue to expect our 2022 cash flow to approach $24 billion, about 1.2 times net income.
And we ended '21 with a debt-to-total capital ratio of 38%.
These ample capital capacities allow us to continue to accelerate our investments, while remaining committed to an advancing shareholder dividend and supporting our expected repurchase of between $5 billion and $6 billion of stock in '22.
Our 2022 adjusted earnings per share outlook of $21.10 to $21.60 is consistent with the view we offered seven weeks ago.
From this distance, and in contrast to the past two years, we expect the seasonal pattern to be more consistent with our historical experience, with just under 50% of full-year earnings in the first half and the first two quarters comparably even.

Summary:
For example, performance in two key elements of our growth strategy, accelerating the transition of patients to Optum-led value-based care and strong United Healthcare growth in serving Medicare Advantage consumers, are both tracking well with the expectations we shared with you at our recent investor conference.
In sum, we enter 2022 with heightened confidence in our ability to execute upon the objectives we set forth in late November.
Full year '21 cash flow from operations was $22.3 billion or 1.3 times net income, about $2 billion above the initial outlook we shared a year ago.