Effect of Continuity of Care on Hospital Utilization for Seniors With Multiple Medical Conditions in an Integrated Health Care System

DISCUSSION

In an integrated system with a shared electronic health record that provides informational continuity, measures of interpersonal continuity of care are less likely to serve as proxies for medical knowledge about the patient, and more likely to reflect the benefits of the patient-clinician relationship. Previous studies demonstrating a relationship between greater COC and lower hospital utilization for patients with MCCs have been conducted with Medicaid, Medicare fee-for-service, and several geographically defined populations in settings where it is not possible to separate these components of continuity.^7,9,29 By demonstrating associations between greater interpersonal COC and lower risk of inpatient or ED admission within an integrated delivery system, our results suggest that interpersonal continuity has a beneficial effect on utilization independent of informational continuity.

Because of the COCI calculation, the absolute effects of increased continuity appear low; however, on a population level, the effects on use of even small increases in continuity may be substantial. For example, based on the information in Table 2, a population of MCC individuals with 3 or more primary care visits would experience a 3% decrease in the probability of an inpatient admission for every 0.1-unit increase in primary care COCI over a 2-year period.

Within the heterogeneous MCC population, at any point in time, there are likely subgroups of patients who use mostly primary care (eg, those having stable multimorbidity), those who may use more episodic or focused specialty care (eg, early cancer survivors), and those who use both (eg, individuals with unstable cardiac disease as well as multiple comorbidities). “Perfect” continuity of care across clinicians for populations having multiple conditions is thus unlikely to be attainable or even desirable. Complex patients will often require consultation from clinicians with different areas of expertise, and very high overall COC may even indicate insufficient access to specialty care.^30,31 Our findings that primary care and specialty care continuity have separate associations with outcomes in different subcohorts likely reflect the actual care needs of a heterogeneous and complex patient population.

Although continuity with primary care, specialty care, or both is beneficial, the optimal balance between primary and specialty care clinicians in caring for patients with MCCs is unclear. Starfield et al noted that increasing morbidity was associated with more specialty care, but not primary care use—often for diagnoses that could potentially be addressed in primary care settings.⁵ And Medicare fee-for-service beneficiaries can see between 3 and 11 unique clinicians (1 to 3 primary care clinicians and 2 to 8 specialists) over a 2-year period.³² These patterns reflect an undesirable degree of care fragmentation. In contrast, cancer survivors who receive shared care between primary care and oncology clinicians have better management of comorbid conditions and receive more preventive services, and outcomes of cardiac patients after myocardial infarction are better with shared care between cardiology and primary care.^33–35 Some complex patients report that specialists may know them as well as their primary care clinicians.³⁶

Interpersonal COC is particularly valued by older and more complex patients with worse health status.^31,36,37 Older MCC patients perceive high COC as a foundation for optimal patient-clinician communication and a component of high-quality care, and are more willing than younger, healthier patients to use their own resources to maintain individual continuity relationships.^18,19 In general, higher COC is associated with greater patient satisfaction, trust in the clinician, a sense of security and partnership in care, and better clinician-patient communication.^21,22,38,39 It is unclear how these constructs are manifested in decreasing the risk of hospital utilization—an outcome that may be more immediately meaningful to systems than to patients. Interpersonal COC with a trusted clinician who implicitly incorporates personal knowledge about patients’ context and values is likely to foster more shared decision making, be associated with greater patient activation, and promote better disease control—all intermediate outcomes that can lower the risk of hospitalization or ED use.^40–42

New models of team-based care may, by design, slightly decrease interpersonal continuity while attempting to increase informational continuity and improve care coordination. Advocates of these models point out that better care coordination improves utilization outcomes, that there is a valid (if relatively unexplored) construct of team continuity, and that such care models provide new technology-based opportunities for patient-clinician communication.^7,30,43 Evaluations of patient-centered medical home practice transitions have been inconclusive, however.^44–47 It remains to be seen whether and how new models of care affect relationships that are meaningful to patients as well as outcomes that are important to delivery systems. Our findings suggest that systems should strive to optimize interpersonal COC (with both primary and specialty care clinicians) in designing team-based models of care for complex patients.

Our investigation has several limitations. First, we required 3 or more visits to calculate a valid COCI value. This approach is consistent with the many previous investigations that use the COCI; therefore, our results are comparable to those in the existing literature. Individuals excluded from the analysis because of insufficient visits had lower morbidity and fewer outcomes, suggesting that this small group had simpler care needs than the analytic cohorts. Second, our findings reflect a patient population with good access to specialty care. In settings with poor access to specialty care, primary care continuity may be particularly important. Third, unmeasured confounding by morbidity burden is particularly relevant in studies of complex patient populations who receive multidimensional care. We incorporated 4 adjustments for morbidity in each of our analyses (the Quan-adapted morbidity index, baseline primary care visits, baseline specialty care visits, and baseline outcome rates) to address this limitation. Fourth, our cohort size did not permit creating subcohorts within each specialty to explore the low overall levels of specialty care COC and to evaluate the effect of COC within different specialties—doing so will be an important area for further study. Finally, we did not address the question of whether primary or specialty care is being used appropriately, but only continuity of care with individual clinicians.

Our investigation also had several strengths. We measured COC as a time-varying variable up until the outcome event and thus avoided potential confounding from changes in care patterns that follow a hospital admission or ED visit. This is a substantial strength relative to cross-sectional analyses. In addition, we studied a large, longitudinal cohort that experienced little loss to follow-up. We also explicitly studied complex patients with 3 or more chronic conditions—an expansion on previous investigations of large and more heterogeneous Medicare populations.

In conclusion, interpersonal continuity of care should be optimized for seniors with MCCs, but not with the single goal of improving hospital utilization. Complex patients value relationships with their clinicians, and different subgroups of patients will benefit from continuity with both primary and specialty care clinicians depending on their care needs. It will be important to understand how patients and clinicians conceptualize these continuity relationships within the context of increasingly integrated care delivery settings, and more multidimensional patient-clinician communication.