A Pilot Study of Local Anesthesia for Inguinal Hernia Surgery in Older Adults

Inguinal hernia repair-the most common general surgery operation in the U.S.-provides a unique opportunity to improve outcomes for older patients by changing surgical practice. Nearly 80% of inguinal hernia operations are performed under general anesthesia versus 15-20% using local anesthesia, despite the absence of evidence for superiority. The choice of anesthesia has particular implications for older adults because they face substantial short- and long-term risk of cognitive and physical decline after exposure to general anesthesia. Consequently, the American College of Surgeons and the American Geriatrics Society have identified a critical need in surgery: determining which operations have better outcomes when performed under local rather than general anesthesia.

Currently, the evidence for choosing an anesthesia technique for inguinal hernia repair in older adults is inconclusive. Several small randomized trials and cohort studies have suggested that using local anesthesia for hernia repair reduces morbidity by one-third, unplanned readmissions by 20%, and operative time and costs by 15% while other studies showed no significant differences. However, there are significant flaws in these studies that severely limit their applicability to older adults: (1) They mainly focused on younger patients with limited comorbidity burden, largely ignoring individuals aged 65 years and older, (2) They did not adequately examine the effects of general anesthesia on cognitive function and quality of life for older adults and their caregivers, (3) They did not consult with stakeholders to identify outcomes relevant to those groups. The current study aims to address these limitations to determine the ideal anesthesia modality for inguinal hernia repair.

The study rationale is that prior to conducting a multisite randomized trial, it is necessary to identify relevant outcomes, understand barriers to greater use of local anesthesia, test study procedures, and confirm our ability to adequately recruit and randomly assign participants. Additionally, the proposed study will provide the applicant with critical training in the design, conduct, and analysis of clinical trials. This will uniquely position the applicant to change surgical care for older adults.

There have been two prior randomized clinical trials that compared local versus general anesthesia for inguinal hernia repair. One study randomized 616 patients in Sweden to local, regional, or general anesthesia. They did not specifically look at older patients but the mean age in each group was 56 years old. They found that the total operative time was five minutes faster for the local anesthesia group (90 versus 95 minutes) the incidence of postoperative pain requiring opioids and catheterization for urinary retention was decreased by 29% for the local compared to general anesthesia group and the rate of unplanned admission was decreased by 19%. A cost-effectiveness analysis conducted by the same group indicated that hospital costs were lower in the local anesthesia group (a difference of €311/$378) and total healthcare costs were also lower (€316/$384). A second trial from Scotland randomized 279 patients to local or general anesthesia, with a mean age of 55 years for both groups. This study did not find a significant difference in operative time, complications, length of stay, pain, or neurocognitive recovery as measured by a battery of tests. However, they did not specifically analyze outcomes in older patients which would tend to dilute the potential benefits of local anesthesia. Equally important, this study focused almost exclusively on healthy patients with smaller hernias, as evidenced by \>90% of patients having an American Society of Anesthesiology score of 1 or 2 and a mean total surgical time of 48 minutes for each group.

There are several observational studies that compare outcomes from hernia repair under local or general anesthesia, and these mostly suggest that local anesthesia is associated with shorter operative time (5-10 minutes), fewer complications (1-3% reduction), and enhanced quality of life. However, only two of these studies look specifically at outcomes for older adults and both suffer from a poor approach to risk adjustment. Additionally, all the observational studies have a limited assessment of complications and failed to effectively evaluate rates of urinary retention and catheterization after surgery. Urinary retention is the most common complication of general anesthesia after hernia repair and results in considerable discomfort for patients who are catheterized to relieve it. Additionally, when patients do not resolve retention in a timely fashion, it results in the need for unplanned admission which increases hospital costs.

The intervention chosen for testing in this study is the choice of anesthesia (local or general) for unilateral inguinal hernia repair. These are the primary methods of anesthesia for inguinal hernia surgery by most surgeons (though some perform the operation under spinal or regional anesthesia, this is rare). Both approaches are used in clinical practice with acceptable known risks and complications. General anesthesia is associated with risks of hypotension, venous thromboembolism, heart attack, stroke, pulmonary dysfunction, cognitive dysfunction, allergic reaction, and malignant hyperthermia. The main risks of local anesthesia include allergic reaction and hypotension (when the anesthetic is improperly injected into a blood vessel).

Eligibility Criteria:
Inclusion Criteria:

* Age \>=65 years
* Presenting to clinic with a unilateral inguinal hernia that is not incarcerated
* Considered suitable for either general or local anesthesia
* Willing to complete all study requirements, including follow-up continuing until six months after surgery

Exclusion Criteria:

* The hernia that the patient is being evaluated for has undergone prior repair
* Any contraindications to general anesthesia
* Allergies to local anesthesia
* Evidence of hernia incarceration or strangulation
* Active local or systemic infection that would preclude the use of mesh for hernia repair
* Need for concurrent surgical repair at the time of hernia repair
* English is not the patient's primary language
* Enrollment in other research studies