First quarter organic net revenue growth was 1.9%.
That reflects solid performance in the U.S., an organic decrease of 20 basis points, and strong international growth of 6.3%, with increases in every world region.
In the U.S., you'll recall that we are comparing to very strong underlying performance in the first quarter of 2020 when we faced headwinds of nearly 4% due to certain 2019 client losses that we previously identified.
Our international performance was paced by 12.4% growth in Continental Europe, where we had a strong start to the year by our media, data and tech offerings as well as McCann Worldgroup.
From the standpoint of our operating segments, Our IAN segment grew 3.2% organically, led by media, data and technology and by the healthcare specialty agencies.
We continue to be highly confident that, over time, we are well positioned to realize the full level of permanent operating expense savings that we've talked about previously, which, as a reminder, annualized at $160 million.
Our first quarter net income as reported was $92 million, which includes the expense of certain nonoperating items.
Our adjusted EBITA was $266 million, a level which is approximately 2.5 times the first quarters of recent years.
Our adjusted EBITA margin was 13.1%.
Diluted earnings per share was $0.23 as reported and was $0.45 as adjusted mainly for our loss on the early extinguishment of debt, the disposition of certain small nonstrategic agencies, both of which are nonoperating expenses, and our expense for the amortization of acquired intangibles.
Given our strong start to the year, and based on the assumption that there'll continue to be a reasonably steady course of public health and global economic recovery, we believe that we can deliver organic growth for the full year in the range of 5% to 6%.
With that level of growth, we would expect to achieve 2021 adjusted EBITA margin of approximately 15.5%.
First quarter adjusted EBITDA, before a small restructuring adjustment, was $265.9 million and margin was 13.1%.
Diluted earnings per share was $0.23 as reported and $0.45 as adjusted.
During the quarter, we refinanced $1 billion of senior notes that had been scheduled to mature over the next few years.
We placed the $1 billion in new notes maturing in 10- and 20-year tranches.
Our net revenue in the quarter was $2.03 billion, an increase of $55.6 million.
Compared to Q1 2020, the impact of the change in exchange rates was positive 1.5%, with the dollar weaker against currencies in most of our largest markets.
Net divestitures were negative 60 basis points.
Our organic net revenue increase was 1.9%.
Our IAN segment was -- grew 3.2% organically, a terrific result against last year, largely non-COVID first quarter.
At IPG DXTRA, the organic change in the quarter was negative 4.8%, which reflects the weight of live events and sports marketing within the segment, the disciplines that have been most significantly impacted by the pandemic.
In the U.S., which was 65% of net revenue in the quarter, our organic decrease was 20 basis points against the challenging comparisons underlying our headline number from a year ago.
International markets were 35% of our net revenue in the quarter and increased 6.3% organically.
Continental Europe grew 12.4%, with increases in every major national markets, including Spain, Germany, Italy and France, driven by increased spend from existing clients.
The U.K. increased 3.5% organically and, again, this is net of continuing headwinds in the events discipline We had solid growth at McCann at our media, data and tech offerings and at MullenLowe.
Asia Pac grew 3.4% organically.
Our organic growth in LatAm was 5%, with particularly strong results across Mexico, Colombia, Argentina and Chile.
Our Other Markets group grew 7.3%, with notably strong performance in the Middle East.
Our net operating expenses, excluding billable expenses and the amortization of acquired intangibles, decreased 6% from a year ago and to 2.8% growth of our net revenue.
The result was first quarter margin expansion to 13.1% from 4.9% a year ago.
As you can see on this slide, our ratio of total salaries and related expense as a percentage of net revenue improved by 340 basis points to 68.7% compared with 72.1% a year ago.
Underneath that, we drove very strong leverage on our expense for base payroll, benefits and tax, which improved by 360 basis points.
We had a lower severance expense ratio, which was only 30 basis points of net revenue compared to 120 basis points in Q1 2020.
At quarter end, total worldwide headcount was approximate 51,200, a decrease of 6.1% from a year ago as a result of our restructuring and regular severance actions taken over the course of last year as well as our business dispositions.
Also on this slide, our office and other direct expense decreased as a percentage of net revenue by 480 basis points to 14.4%.
We continue to have significant decreases in our expenses for occupancy, driving year-on-year leverage of 110 basis points.
We leveraged all other office and other direct expense by 370 basis points, which includes the decreased expense for travel and bad debt.
Our SG&A expense was 1.4% of net revenue, an increase of 30 basis points.
Our expense for the amortization of acquired intangibles in the second column was $21.6 million.
The restructuring charges were $1.3 million.
Below operating expenses, in column 3, we had a pre-tax loss in the quarter of $12.5 million in other expenses due to the disposition of a few small nonstrategic businesses.
To the right of that, our pre-tax loss due to the early extinguishment of debt was $74 million, which relates to the refinancing and extending the maturities of $1 billion of our senior notes.
At the front of the slide, you can see the after-tax impact per diluted share of each of these adjustments, which bridges our diluted earnings per share as reported at $0.23 to adjusted earnings of $0.45 per diluted share.
Cash used in operations was $249.8 million compared with the use of $277.1 million in Q1 2020.
During this year's first quarter, cash used in working capital was $496.9 million and follows our fourth quarter of last year, where we generated over $1 billion from working capital.
In our investing activities, we used $28 million for capex in the quarter, which was essentially offset by the net proceeds from the sales of investments.
Our financing activities in the quarter is $212.7 million, which reflects the redemption and issuance of long-term debt and our common stock dividends.
Our net decrease in cash for the quarter was $492.7 million.
We ended the quarter with $2.02 billion of cash and equivalents compared with $1.55 billion a year ago.
Under current liabilities, the current portion of long-term debt refer to our $500 million, 3.75% senior notes, which matures in October of this year.
Again, we have the maturity in October this year and then only $250 million due in April 2024.
We've increasingly seen the amounts of time people spend online, picking out content that's engaging, informative, entertaining, or some combination of all 3.
Since the start of the year, we onboarded or promoted top talents across the organization, once again received high levels of industry recognition and saw solid new business performance, where we remain net positive for the past 12 months.
Along with most awarded networks of 2020 in the Drum rankings, McCann New York came in at number four on that list in terms of the top 100 agencies worldwide.
Looking forward, we will stay focused on unlocking the enormous opportunities that exist due to the changes and disruptions that have accelerated during these past 12 months.

Summary:
Diluted earnings per share was $0.23 as reported and was $0.45 as adjusted mainly for our loss on the early extinguishment of debt, the disposition of certain small nonstrategic agencies, both of which are nonoperating expenses, and our expense for the amortization of acquired intangibles.
With that level of growth, we would expect to achieve 2021 adjusted EBITA margin of approximately 15.5%.
Diluted earnings per share was $0.23 as reported and $0.45 as adjusted.
Our net revenue in the quarter was $2.03 billion, an increase of $55.6 million.
At the front of the slide, you can see the after-tax impact per diluted share of each of these adjustments, which bridges our diluted earnings per share as reported at $0.23 to adjusted earnings of $0.45 per diluted share.