We found that women in health plans that have a defined network of providers or gatekeeper requirements are more likely to report having received screening mammography in the past two years than women in plans without these characteristics. In contrast, restricting out-of-network coverage, use of cost containment, cost sharing, and breadth of benefit coverage did not appear to affect mammography use. Moreover, we found no significant difference in screening mammography using a more traditional comparison of respondents enrolled in managed care versus indemnity plans. These findings indicate the importance of moving beyond simple, dichotomous categorizations and older typologies of managed care, to examine the effect of individual health plan characteristics on the utilization of health services.
Our findings suggest that health plans with defined provider networks or gatekeeper requirements may help facilitate the appropriate use of highly recommended preventive services, such as screening mammography. Limiting the pool of providers may increase the ability of the plan's administrators to convey information to providers, including the importance of promoting mammography among patients. For example, many plans disseminate information on preventive care through provider newsletters, meetings, websites, or e-mail reminders. Such strategies may be even more effective when combined with a defined provider network arrangement. Gatekeepers also serve as important messengers to patients regarding preventive screening and the appropriate adherence to mammography guidelines. As a care coordinator for their patients, gatekeepers may contribute to improved access to care, continuity of care, or the ability to effectively encourage the use of preventive services. Gatekeeper requirements may also increase the likelihood of having a usual source of care, which in previous studies has been shown to increase the use of screening mammography (Gordon, Rundall, and Parker 1998
Most researchers would agree that studies of health services use should look beyond the broad categorizations of managed care, and the differences in mammography rates among women in plans with different plan components observed in this study supports this view. However, it is important to note that our analyses address only one type of health service, a preventive service that is widely available and strongly promoted among women of certain age groups. The relationship between individual plan characteristics and other types of health services, particularly ones that are less uniformly recommended, could be quite different. For example, a recent study of prostate cancer screening, a more controversial screening procedure, found that having a defined provider network and gatekeeper requirements were associated with lower
rates of utilization, while enrollees facing less financial burden (i.e., lower copayments, deductibles, and coinsurance) were more
likely to be screened (Liang et al. 2004
). Thus, plan characteristics may have a very different impact on utilization, depending on the type of health service being considered, how universally it is recommended, and even patient gender. These relationships should be explored more fully in future studies.
Our analyses were subject to several limitations. First, the MEPS does not provide information on every plan characteristic that may affect utilization in a complex health care environment. Our mapping of MEPS onto a framework of health plan factors indicates that while the survey includes a wide range of plan variables, large gaps remain. As in most population-based health surveys, factors at the enrollee level were the most likely to be included, while little information is measured at the provider, plan, and particularly, medical group level (e.g., provider compensation and contractual arrangements). No one survey can measure all elements related to health insurance, nor should it. However, the use of followback surveys—whether based on plan booklet abstraction or surveys of employers and other insurance providers—can expand the measurement of plan factors and add validity to household data.
Moreover, although study analyses did not demonstrate a significant association between mammography use and several of the health plan variables that we tested (i.e., restricted out-of-network coverage, cost containment, cost sharing, benefit coverage), this may be due to insufficient sample size and power or the fact that many of the plan measures were not directly relevant to mammography screening. For example, our cost-sharing variables were based on out-of-pocket costs for a general office-based doctor visit, rather than being specific to a mammography appointment. The lack of significant associations for some plan characteristics could also reflect the broad diffusion of mammography as a preventive service. Screening mammography is a mandated benefit in most states, receives high public attention, and is tracked within plans as a HEDIS measure. Another screening service with less consumer awareness and a lower diffusion state of its technology (e.g., colorectal screening) could potentially be related to some of these “non-significant” factors.
A further limitation is that our study variables were based primarily on self-report, and may be subject to misclassification error. Although self-reported measures can be inaccurate, our key variables appear reasonably accurate for this study (e.g., 85 percent of gatekeeper plans based on plan booklet data were also classified as gatekeeper plans per self-report). Previous studies also found that respondents are able to recall accurately whether they had a mammogram in a one- to two-year timeframe (Barratt et al. 2000
), which was the focus of our analyses.
Another potential problem is the temporal ordering of the dependent and independent variables, an issue typically ignored in prior studies (Phillips, Morrison et al. 1998
). While our key plan characteristics were recorded at the time of the MEPS survey, utilization of mammography screening occurs at a point in time earlier. We found similar results in sensitivity analyses restricting our sample to individuals who had continuous insurance coverage in the past two years, using an outcome variable closer to the utilization timeframe (screening within the past year), and using MEPS event level data (i.e., data obtained at the time of a specific visit) that reported both mammography screening use and insurance information simultaneously. However, we could not completely control for possible temporal bias.
Finally, our findings should not be interpreted as demonstrating a direct causal relationship between individual plan characteristics and reported mammography use. The correlation among some of the health plan characteristics was quite high, making it difficult to attribute differences in utilization to one particular plan feature. Due to multicollinearity concerns and model instability, it was not workable to specify all of the health plan variables in the same regression model. We must be careful to conclude that being in a plan with either a defined provider network or a gatekeeper was associated with higher mammography use in this study. Future work is needed to fully ascertain the independent effects of these plan features and to test composite measures of health plan characteristics using comprehensive data sources. While it is important to be cautious about attributing an effect to a specific feature, given the scarcity of research in this area, our findings using a repeated regressions approach warrant further attention.
The health plan components model adopted for these analyses is an important first step in understanding how the different organizational and financial levers in the current health care environment affect individuals' use of health services. We developed an updated framework of health plan measures that is intended to be useful to researchers working with MEPS and similar surveys. Moreover, this study is one of few studies to use recent, nationally representative data to examine the impact of individual plan features on mammography completion. Consumers and policymakers should recognize that individual characteristics of the plan—not just whether or not it is managed care—may affect utilization and outcomes. Although it may be convenient to rely on the broader categorizations in designing policy, it is essential to look past the traditional labels to the specific health plan features that are the foundation of policy concern.