In most of these studies, however, facility size was not controlled for in the analysis, which makes it difficult to know whether improvement is truly an effect of specialization. Other limitations of the available research in this area are the small number of institutions included in the studies and a lack of information on whether underlying differences in patient populations across facilities are taken sufficiently into account. Furthermore, the potential for publication bias is significant in these kinds of studies (e.g., specialty centers would be likely to publish only positive results). At this time the evidence is insufficient, and well-designed studies are needed to understand the relationship between institutional specialization and outcomes.
Very little can be said about the effects of physician specialization on outcomes of cancer care. Only one U.S. study was found that compared the outcomes of patients cared for by physicians with different levels of training. The one U.S. study and several studies conducted outside the United States appear consistently to show improved outcomes with specialization, but the definitions of specialization varied widely. For three of the studies, the outcomes of patients with ovarian cancer were compared according to whether their provider was a general surgeon or a gynecologist. Other studies used different definitions of specialization (e.g., training, interest, practices such as keeping separate records for cancer patients). Here again, the evidence is insufficient, and well-designed studies are needed to understand the importance of physician specialization.
Few studies compared cancer care under managed care with fee-for-service care, and studies are usually limited to group-or staff-model HMOs that have a relatively small share of the total managed care enrollment. The limited body of evidence suggests that processes and outcomes of care in these managed care settings are equal to or better than those in fee-for-service settings. Recent evidence suggests that there is significant variation in quality of care among HMOs.
There are a number of data systems in place that could substantially improve the quality of information available to provide additional insights into which structures and technical processes of care may lead to better patient outcomes. The National Cancer Data Base, for example, could be used more extensively to address quality issues if a nationally representative sample of facilities and providers was used. The SEER-Medicare-linked database appears to be an underutilized resource with which to evaluate aspects of care that affect outcomes for Medicare beneficiaries. Existing data systems, however, must be enhanced so questions about quality of care can be answered comprehensively on a national scale. An effective system would have to capture information about
It may be costly and difficult to obtain all of the desirable data elements for all individuals in any one data system, so existing databases could be used effectively to identify a sample of patients for augmented data collection in targeted studies. Linking available databases is another