Cost and efficacy of the substitution of ambulatory for inpatient care.

The substitution of ambulatory for inpatient care has become a common cost-containment proposal; it assumes that an equivalent or better clinical outcome at lower cost will result. However, when criteria for measuring cost and efficacy are appropriately defined, there is little published information available that support this assumption. Only four of 134 relevant papers that we analyzed provided enough data on both cost and efficacy to allow statistically valid conclusions. Two of these four demonstrated that potential savings would be accompanied by a slightly poorer clinical outcome; two showed ambulatory care to be as effective as inpatient care and less costly. Future study should include both appropriate calculations of costs and properly controlled measurements of clinical outcome. Indirect costs cannot be ignored in such calculations if the total costs of illness, not simply payments to the health industry, are to be reduced.