Roland Sackers
Analyst · Goldman Sachs
Thank you, Thierry. Hello, everyone. Thank you as well from me for joining our call. Our results for the first quarter were ahead of our goals and show QIAGEN is building momentum. Net sales of USD 459 million declined 5% at actual rates and also 5% at constant exchange rates despite some modest pressure on results due to the strengthening of the U.S. dollar. Consumables and related revenues had to absorb the COVID headwinds from 2023 and this led to the 4% CER decline over the year ago period. Instrument sales declined 9% CER, reflecting the challenging environment for capital purchases. At the same time, we saw good placement trends for QIAsymphony, QIAcuity and QIAstat-DX systems.
Among the 4 product groups, Diagnostic Solutions led the performance. Here again, we saw double-digit gains for QuantiFERON and QIAstat-Dx, while our personal healthcare business also delivered single-digit improvements over the first quarter of 2023. In sample technologies, as mentioned earlier, we were pleased to see higher consumable sales for automated kits. The results for sample technologies take into consideration that we, along with other companies, had larger price increases at the start of 2023.
This year, the price increase was more in line with our historical levels of a low single-digit increase. Additionally, we faced COVID-19 headwinds with an underlying sales decline at a modest low single-digit CER rate. We are anticipating improved growth trends during the year as we launch marketing initiatives to highlight the differentiation of our portfolio. Additionally, the decision by Congress for essentially flat federal funding for life science research in the U.S. budget was in line with our planning, and this outcome provides customers with clarity on budget.
In PCR/nucleic acid amplification, the QIAcuity digital PCR system continued on a solid trajectory, delivering solid double-digit CER sales growth over the first quarter of 2023. Key drivers have been the expansion of consumable sales particularly to biopharma customers, along with ongoing high levels of instrument placements. We anticipate better trends in this product group as the year progresses.
In Genomics/NGS, sales were unchanged from the first quarter of '23. We saw higher sales of universal library prep kits for use with third-party next-generation sequencers. Sales in our QIAGEN Digital Insights bioinformatics business were slightly lower for the quarter due to the timing of a large customer contract, but we continue to see solid demand trends for this business and continue to expect sales growth above 10% CER for '24.
Among the regions, sales in the Americas reflected the impact of COVID headwinds. Results benefited from improving demand for QuantiFERON, QIAstat and QIAcuity consumables. The Europe, Middle East, Africa region saw sales declined 2% CER over the first quarter of '23, but underlying results rose at a single-digit CER rate excluding the pandemic headwinds.
Among the top countries where France, Switzerland and the United Kingdom. Our regional expansion in the Middle East helped these results. In the Asia Pacific, Japan region, sales in China declined at a double-digit CER rate, reflecting the macro challenges in this market that are not showing signs of improvement. However, at the same time, we saw improved results in India and South Korea and continue to see dynamic opportunities in targeted emerging markets.
Let's now review the rest of the income statement. The adjusted gross margin was 67.1% of sales modestly lower than the first quarter of '23 as we worked on increasing efficiencies after a period of capacity utilization expansion in recent years. For the first quarter, adjusted operating income declined 5% to $118 million from the first quarter of '23, in line with the decline in sales. We focus on investing in the R&D and delivered an improvement in the adjusted operating income margin to 25.7% of sales compared to 25.6% in the year ago period.
To close out the income statement, adjusted EPS was $0.46 for the first quarter, while results at constant exchange rates were $0.47 and ahead of the outlook for at least $0.44. The adjusted tax rate of 20% was at the high end of the outlook, while the average diluted share count at 226 million was also in line with our expectations.
Turning to cash flow. The trends at the start of '24 have been very positive. Operating cash flow nearly doubled to USD 133 million over the first 3 months of '23 with significant improvement of working capital management and inventory management as well as collecting of accounts receivables. Free cash flow rose nearly 1.5x over the level in the first quarter of '23 to USD 97 million while at the same time, we saw a slight increase in investments in property, plant and equipment as we continue transitioning to our new enterprise resource planning environment.
We are paying particular attention on measures to ensure a high level of cash conversion while maintaining adequate supplies to provide products to customers around the world without disruptions especially in light of the current macro trends and logistical challenges.
Continuing with the balance sheet. Our liquidity position was about USD 893 million at the end of the first quarter of '24 compared to $1.1 billion at the end of '23. This level includes the $300 million of cash payout for the synthetic share repurchase in January, which removed about 6.8 million shares outstanding. As a result, our leverage ratio at the end of the first quarter stood at 0.9x net debt to EBITDA compared to 0.6x at the end of '23. As a reminder, we have about $600 million of debt reaching maturity in September.
Given our healthy balance sheet and strong cash flows, we want to create value through our capital allocation policy that has served us well. We continue to invest organically into the business while also reviewing various targeted bolt-on acquisitions that would complement our portfolio. The share repurchase at the start of '24 is also a signal of our views about the valuation of QIAGEN and our commitment to increasing returns.
I would now like to hand back to Thierry.