Cost comparison favors minimally invasive over conventional AVR

“Measurement of cost and outcome, the determinant of ‘value’ in health care, is assuming increasing importance in the evaluation of all medial interventions, especially those surgical procedures done frequently and at higher cost,” wrote Dr. Verdi J. DiSesa in his invited commentary (J. Thorac. Cardiovasc. Surg. 2015 [doi:10.1016/j.jtcvs.2015.01.049]).

Although applauding the timeliness and importance of analyzing the costs and outcomes in propensity-matched patients undergoing aortic valve replacement via full sternotomy of mini-AVR using a partial sternotomy or limited thoracotomy incision, he questioned some of the methodology. The cost-to-charge ratio used, which provides an estimate of the cost of services, is not uniform throughout departments in a single hospital, and differs from hospital to hospital, although the latter was accounted for. He suggested that “activity-based costing” would have been a better approach, although more labor intensive. In this approach, every encounter with a caregiver is assigned a unit cost and the cost of a patient encounter is calculated by estimating the number of units of service and multiplying by the unit cost for service.

“This method is demanding of resources but has the potential to become the most accurate and therefore the preferred way to determine the costs of medical services,” he wrote. In addition, the authors included but did not separately analyze patients having AVR via minithoracotomy.

“What might be the conclusions of this research were these patients excluded or analyzed separately?” he asked.

In terms of the propensity model, the matching procedure included only three clinical factors – STS Predicted Rate of Mortality (PROM) score, the operative year, and the surgeon who performed the procedure – resulting in 35% of patients remaining unmatched, which may have biased the results.

This analysis, Dr. DiSesa concluded, is “perhaps an early version of the kind of analyses, which increasingly will be required for the evaluation of the services provided by all health care providers, not only cardiac surgeons.”

Dr. DiSesa is professor of surgery at Temple University, Philadelphia.