Brian King
Vice President, Treasurer and Head of Investor Relations at Intuitive Surgical
Thank you, Jamie. Overall, first quarter procedure growth was 16% year-over-year, compared to 26% for the first quarter of 2023 and 21% last quarter. In the U.S., first quarter 2024 procedure growth was 14% year-over-year, compared to 26% for the first quarter of 2023 and 17% last quarter. First quarter growth was led by procedures within general surgery, with strength in cholecystectomy, colon resection and foregut procedures. Growth in bariatrics procedures continued to moderate, and was flat year-over-year.
Outside of the U.S., first quarter procedure volume grew 20%, compared with 28% for the first quarter of 2023 and 29% last quarter. Over 70% of procedure volume growth led by procedures beyond urology, with strength in colon resection, hysterectomy and lung resection procedures. In Europe, first quarter growth continued to be led by general surgery and gynecology procedure categories. Germany and the U.K. procedure performance led the region, with both experiencing strong growth in colon and rectal resection and hysterectomy procedures.
In Asia, growth in the first quarter was led by China, with strong procedure performance in urology and gynecology procedures. Year-over-year procedure growth in the country benefited from a comparison period, where procedures were beginning to recover from COVID during the first quarter of 2023. In Japan, while we experienced a moderation in growth in urology, overall procedure growth was healthy, with strength in general surgery procedures, such as colon and rectal resection, and gynecology procedures. Effective June 1, 2024, five additional procedures will have reimbursement in Japan, with two existing rectal resection procedures receiving an increase in reimbursement for equivalency to laparoscopic surgery. The opportunity for these procedures is relatively modest, but continues to support the adoption of minimally invasive robotic surgery across a growing set of procedures.
Now, turning to the clinical side of our business. Each quarter on these calls, we highlight certain recently published studies that we deem to be notable. However, to gain a more complete understanding of the body of evidence, we encourage all stakeholders to thoroughly review the extensive detail of scientific studies that have been published over the years.
In the first quarter of this year, Dr. Jae Hwan Choi and team from University of South Florida and Tampa, Florida, published a meta-analysis of randomized controlled trials, describing outcomes of robotic-assisted abdominal pelvic surgery in the journal, Surgical Endoscopy. This analysis included a review of 50 publications published through April 2021, included over 4,800 patients from randomized controlled studies, and covered a variety of abdominal pelvic surgical procedures, including anti-reflux, gastrointestinal, colorectal, urologic, hernia repair and gynecologic procedures. The authors compared robotic-assisted outcomes with those from both open and laparoscopic procedures.
When compared to the open approach, robotic-assisted procedures had lower rates of post-operative complications, with a 32% lower risk of post-operative complications across all procedures, as well as less estimated blood loss with a mean difference of 286.8 milliliters. Furthermore, length of stay was, on average, 1.7 days shorter for robotic-assisted procedures. Relative to the laparoscopic approach, rates of conversion to open for the robotic-assisted group was approximately half the rate of the laparoscopic approach. Length of stay was also shorter for robotic-assisted procedures.
Interestingly, the authors also reported an analysis on the impact of surgeon experience, comparing inexperienced versus experienced surgeons, and found that the experienced robotic-assisted surgeons had a lower risk of intraoperative complications, with significantly less risk in the experienced group as compared with the laparoscopic group, as well as a lower risk of conversion to open for the experienced surgeon relative to the laparoscopic group, with comparable operative times compared to laparoscopy with experienced surgeons.
The authors concluded, in part, that their results suggest robotic surgery may shorten length of stay and rates of conversion to open when compared to laparoscopy, with experienced mitigating potential differences in operating time, while improving rates of intraoperative complications and conversions to open surgery.
In March this year, Dr. Nicole Lunardi from the University of Texas Southwestern, along with colleagues from other hospitals and data support from the Intuitive Health Economics Outcomes Research team reported outcomes, describing the use of robotic technology in emergency general surgery cases. Published in JAMA Surgery, this analysis used the PINC AI Healthcare Database, a database that collects data from over 800 facilities to identify adult patients undergoing urgent or emergent cholecystectomy, colectomy, inguinal and ventral hernia repairs between 2013 and 2021.
For reference, emergent procedures were described as those required for life-threatening or potentially disabling conditions, while urgent procedures were those where immediate intervention was needed and prioritized as first available. Over 1 million urgent or emergent procedures were identified. During the study period, the use of robotic-assisted surgery for all procedures experienced a 3.5-fold increase in cholecystectomy, a 6-fold increase for colectomy and 38-fold increase in inguinal hernia repairs. Notably, increases in the robotic-assisted approach corresponded to decreases in the open approach for these procedures, as well as a decrease in laparoscopy for cholecystectomy and colectomy procedures.
Furthermore, a propensity score matched analysis demonstrated a lower risk of conversion to open for the robotic-assisted approach when compared to laparoscopy. Cholecystectomy procedures with a 45% lower risk of conversion, colectomy with a 63% lower risk, inguinal hernia repair with a 79% lower risk, and ventral hernia repair with a 70% lower risk of conversion. The authors concluded, "The application of robotic surgery in emergency general surgery has steadily increased in the past decade, which is especially useful in older patients with several comorbidities. As observed in this cohort study, compared with laparoscopic surgery, robotic surgery appears to have resulted in lower rates of conversion to open surgery from 2013 to 2021. Robotic surgery also leads to a shorter or comparable post-operative length of stay in the hospital. Nevertheless, open surgery remains a key component for most emergency general surgery. As robotic surgery continues to increase in emergency general surgery, barriers to implementation need to be addressed and optimized through coordinated efforts across stakeholders."
I will now turn to our financial outlook for 2024. Starting with procedures. On our last call, we forecasted full-year 2024 procedure growth within a range of 13% and 16%. We are now increasing our forecast and expect full-year 2024 procedure growth of 14% to 17%. The low-end of the range assumes further weakness in bariatrics procedures, along with challenges in China from increasing provincial robotic competition and delayed tenders impacting capital placements, and therefore, procedure growth. We also assume there is no benefit of patient backlog in the year. At the high-end of the range, we assume bariatrics continues at flat to slightly positive growth rates and factors in China don't have a significant impact on our business. In addition, we assume any backlog of patients would decline throughout the year.
Turning to gross profit. We continue to expect our pro forma gross profit margin to be within 67% and 68% of net revenue. Pro forma gross profit margin in 2024 reflects the impact of growth in our newer products, da Vinci 5, Ion and SP, and the impact of capital investments that will come on to support the growth of our business. Our actual gross profit margin will vary quarter-to-quarter, depending largely on product, regional and trade-in mix, and the impact of new product mix.
Turning to operating expenses. We are holding our guidance for pro forma operating expense growth to be between 11% and 15%. We continue to expect our non-cash stock compensation expense to range between $680 million to $710 million in 2024. We are holding our guidance for other income, which is comprised mostly of interest income, to total between $290 million and $320 million in 2024. With regard to capital expenditures. We continue to estimate a range of $1.0 billion to $1.2 billion, primarily for planned facility construction activities. With regard to income tax, there is no change to our guidance of 2024 pro forma income tax rate to be between 22% and 24% of pre-tax income.
That concludes our prepared comments. We will now open the call to your questions.