Factors predicting Medicare national coverage: an empirical analysis

Interventions considered to be particularly controversial or expected to significantly impact the Medicare program in the United States are considered in National Coverage Determinations. Medicare coverage for such interventions is limited to those deemed "reasonable and necessary" for the diagnosis or treatment of an illness or injury. What constitutes reasonable and necessary has not, however, been clearly defined.

To determine factors associated with positive National Coverage Determinations.

A dataset of coverage decisions from 1999 to 2007 (n=195) was created with the following variables: direction of coverage decision; quality of supporting evidence; availability of alternative interventions; cost-effectiveness of intervention; type of intervention; coverage requestor; and year of decision. Univariate and multivariate logistic regression analysis was used to determine factors associated with positive coverage.

The following variables were independently associated with positive Medicare coverage: good or fair quality supporting evidence (adjusted odds ratio, OR=6.04, P<0.01); presence of an alternative intervention (OR=0.130, P<0.01); no associated estimate of cost-effectiveness (OR=0.190, P<0.05). In addition, in comparison with coverage decisions made in the years 1999 to 2001, those made in the years 2002 to 2003, 2004 to 2005, and 2006 to 2007, were associated with positive coverage [ORs of 0.311 (P<0.05), 0.310 (P<0.1), and 0.109 (P<0.01), respectively].

Findings suggest that good or fair quality supporting evidence is a strong predictor of positive coverage. Availability of alternative interventions, more recent decisions, and lack of an associated estimate of cost-effectiveness are associated with a decreased likelihood of positive coverage. The findings highlight Medicare's move to evidence-based coverage decisions, and suggest that coverage decisions are influenced by the availability of cost-effectiveness evidence.