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Introduction: Groin hernia surgery is one of the most common surgical procedures world-wide. Although mainly uncomplicated, the large volume of these operations makes it important to consider severe postoperative complications. The Swedish Hernia Register (SHR) started in 1992 and has grown to include more than 95% of all groin hernia operations performed in Sweden empowering it to be merged with other registers in population-based studies. The aim of this thesis is to merge SHR with other nation-wide registers to analyse postoperative mortality, cardiovascular morbidity, surgical hazards, as well as to study the influence of prostatectomy upon the risk for subsequent groin hernia surgery.

Methods: SHR was interlinked with the Cause of Death Register to find standardised mortality ratio, the National Prostate Cancer Register to find incidence of groin hernia surgery after prostatectomy compared to a control group and with the National Patient Register to find morbidity within 30 days of groin hernia surgery. In paper II, medical records of deceased patients were retrieved and scrutinised.

Results: Elective groin hernia surgery was found to be a low risk procedure even for elderly patients. The mortality risk within 30 days of emergency surgery was raised sevenfold compared to that of the background population. Women had a threefold increased risk of postoperative mortality compared to men. Patients with bowel obstruction, not examined for groin hernia in the emergency room, were subject to more radiological examinations and were operated significantly later than patents with a clinical diagnosis of groin hernia. Compared to men, significantly fewer women were examined for groin hernia in the emergency ward, 61% vs. 78%, (P=0.04). High age, co-morbidity, emergency operation, and regional anaesthesia were risk factors for cardiovascular events. Compared to open anterior mesh repair, all other methods were associated with increased risk of surgical complication, intra-operatively or postoperatively. A threefold increase in groin hernia surgery was seen after radical prostatectomy, conventional as well as minimally invasive.

Discussion: Women are significantly overrepresented concerning mortality after groin hernia surgery. This thesis shows the importance of nation-based registers in the analysis of infrequent phenomena in surgical care.