Cost effectiveness of prophylactic appendectomy: A Markov model

Karina A Newhall, MD1, Ben Albright, MS2, Philip P Goodney, MD, MS3, Thadeus L Trus, MD4. 1Veterans Affairs Outcomes Group, Veterans Affairs Medical Center, White River Junction, Vermont, 2Yale School of Medicine, 3Dartmouth Hitchcock Medical Center; The Dartmouth Institute for Health Policy and Clinical Practice; VA Outcomes Group, 4Dartmouth Hitchcock Medical Center

Introduction: The role of prophylactic (or incidental) removal of a grossly healthy appendix during unrelated pelvic or abdominal surgery to eliminate the future risk and costs of appendicitis remains controversial.  No publications to date employ a rigorous cost-effectiveness model that includes the varying risk of appendicitis over a lifetime, the possibility of antibiotic treatment, or the societal cost of the disease. The objective of this study was to determine whether prophylactic appendectomy performed at the time of an unrelated elective laparoscopic surgery could be cost saving for the health care system from a societal perspective. We hypothesized that given the higher incidence of appendicitis in young adults, this approach would be cost-effective in younger patients.

Methods: We considered hypothetical patient cohorts of varying ages from 18 to 80, undergoing elective laparoscopic abdominal and pelvic procedures. A Markov decision model using cost per-life year as the main outcome measure was constructed to simulate the trade-off between cost and risk of prophylactic appendectomy and the ongoing risk of developing appendicitis, with downstream costs and risks. Rates, probabilities, and costs of disease, treatment, and outcomes by patient age and gender were extracted from the literature. Sensitivity analyses were conducted using complications and costs of prophylactic appendectomy.

Results: With our base case assumptions, including added cost of prophylactic appendectomy of $660, we find that prophylactic removal of the appendix is cost saving in young patients (18-27 for males, and  18-28 for females) undergoing elective surgery.  The margin of cost savings increases exponentially with age: a 20 year old female undergoing elective surgery could save $130/life year by undergoing a prophylactic appendectomy, while a 40-year old female would lose $130/life year. When the risk of the prophylactic appendectomy exceeds the risk of laparoscopic appendectomy for appendicitis or the cost exceeds $1080, it becomes more cost-saving to forego the prophylactic procedure.

Conclusions: Prophylactic appendectomy can be cost saving for patients younger than age thirty undergoing elective laparoscopic abdominal and pelvic procedures.

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