WEDNESDAY, June 25 (HealthDay News) -- About 234 million major surgeries are performed worldwide each year, and surgery rates are much higher in high-income countries than in low-income countries, U.S. researchers report.

Dr. Thomas Weiser, of the Harvard School of Public Health, and his colleagues defined major surgeries as any incision, excision, manipulation or suturing of tissue occurring in an operating room and requiring local or general anesthesia or profound sedation to control pain. They analyzed surgical data from 56 countries.

The rate of major surgeries was 37 times higher in countries that spend more than $1,000 per person on health care than in countries that spend less than $100 per person on health care -- 11,110 per 100,000 people per year versus 295 per 100,000.

High-expenditure (more than $1,000 per person) and middle-expenditure ($400 to $1,000) countries have 30.2 percent of the global population but accounted for 73.5 percent (172.3 million) of surgeries worldwide in 2004. Low-expenditure countries (less than $100) have 34 percent of the population but only had 3.5 percent (8.1 million) of all surgical procedures in 2004.

The researchers also examined surgical safety. It's been estimated that rates of major complications following inpatient surgery are between 3 percent and 16 percent in developed countries, including death rates of 0.4 percent to 0.8 percent. Studies suggest that death rates after major inpatient surgery in developing countries are 5 percent to 10 percent, with death rates from anesthesia alone as high as one in 150 patients.

Even using conservative estimates, 7 million patients a year suffer complications following surgery, and half of them are likely preventable, said the study authors.

The volume of surgery being performed worldwide suggests that surgical safety has emerged as a substantial global health issue, said the researchers, who suggested that public health interventions and educational projects may help improve surgical safety and quality of care.

"Our findings suggest that surgery now occurs at a tremendous volume worldwide, in settings both rich and poor. The implications are substantial. This unappreciated worldwide growth shows a great need for public health efforts to improve the monitoring, safety and availability of surgical services, especially in view of their high risk and expense. A public health strategy for surgical care is paramount," the researchers concluded.

The study was published in this week's issue of The Lancet.

More information

The U.S. Agency for Healthcare Research and Quality has more about surgery.