We examined process and outcomes of care for HIV-infected patients randomly assigned to 2 different teaching settings, IDC and GMC. Despite remarkably similar process of care, potentially due to a teaching program for residents in GMC, we found a difference in health care utilization between patients randomly assigned to these clinics. Specifically, utilization of the emergency department and the number of hospital days in the 12-month follow-up period were significantly higher for patients randomized to GMC. These differences remained even after adjusting for baseline imbalances between the 2 patient groups.
Increased hospital use for patients cared for by generalist physicians has been previously suggested in a retrospective evaluation of patients enrolled in the New York State Medicaid program.1
Patients cared for by generalists had greater odds of being hospitalized (odds ratio 2.2) and, if hospitalized, had a longer length of stay. Our results prospectively confirm that utilization of hospital services was higher for the patients followed by GMC physicians. Furthermore, our study extends previous efforts in that we defined and measured key components of high quality primary care for HIV-infected patients. For the most part, the provision of these components of care was excellent (e.g., over 90% of patients received appropriate PCP prophylaxis). In fact, the only differences in process of care (tuberculosis screening) favored the care for GMC patients.
Our findings contrast the previous work of Kitahata et al.3
who performed a retrospective medical record review evaluating AIDS patients cared for by family physicians within a staff model-HMO. Kitahata et al. reported that more experienced doctors (all generalists) were more likely to prescribe appropriate PCP prophylaxis, whereas in our cohort, provision of PCP prophylaxis was high and comparable between GMC and IDC. The physicians in the Kitahata study, however, had received no targeted education in HIV-care. Kitahata et al.'s study also documented that patient survival was associated with the experience of individual providers. The experience garnered from the care of even small numbers of HIV infected patients (2 to 5) led to improved patient outcomes, specifically a lower risk of death. While our study was not powered to detect differences in mortality between the patient groups, the numbers of patients followed per physician in Kitahata et al. is consistent with the numbers of patients cared for by most of the providers in our study.
Use of antiretroviral agents is a big determinant of survival and their use is associated with lower use of hospital services.13–15
Previous studies have linked physician experience to utilization of antiretroviral medications.2,3
Markson et al.2
performed a retrospective analysis of New York State Medicaid claims comparing utilization of zidovudine therapy by generalist versus specialist physicians. In our prospective cohort, however, the overall percentage of patients who were prescribed antiretroviral medications and the number of medications prescribed was similar, even when controlling for temporal trends.
In our study, differences in utilization may be related to differences in overall and HIV-specific clinical experience between the 2 groups of physicians. In IDC, of the 18 providers who cared for patients, only 56% of them were residents, the remaining physicians being fellows and attending physicians. In GMC, all of the 49 doctors were residents supervised by non-ID attending physicians. Residents and attending physicians might be quite different in their use of strategies such as telephone medicine or reliance on midlevel providers to handle acute issues between visits.
Not only did the doctors differ in level of training, they differed in the amount of experience that was provided within the study cohort. In GMC, medical residents with little or no prior HIV-related ambulatory care experience assumed primary responsibility for all of the HIV-infected patients that were randomly assigned to that clinic. Because there were many GMC physicians who provided care, each individual physician cared for few patients in the context of the study. In contrast, in IDC, fellows and attending physicians provided care for more HIV-infected patients both within the study. Although IDC physicians averaged 10 HIV-infected study patients, they also cared for a significant number of HIV-infected patients outside the study. In contrast, physicians in GMC, cared for few, if any, HIV-infected patients outside of the study cohort. Thus, physician experience was vastly different between the 2 groups of doctors.
In addition to differences between the physicians in the 2 groups, there were important differences in clinic structure and support. The ID attending physicians are available in clinic multiple half days each week and may accommodate acute needs for the patient population more readily than in the GMC. In contrast, residents in GMC had clinic one half day each week and they were not organized into practice groups or coverage teams. When their patients needed care between scheduled clinic visits, GMC residents may have been less available. Nursing and social work support were organized differently in the 2 different clinic settings. Staff in IDC had a very targeted focus on the case management of HIV-infected patients with 3 social workers available. In contrast, GMC is set up to manage the more diverse needs of a population with multiple chronic and acute diseases with only 1 social worker available.
The population we studied was exclusively uninsured or government insured and nearly 80% of patients were black. Our results in this population are consistent with results from the HIV Cost and Services Utilization Study, a national survey based on a sample of the adult U.S. population infected with HIV.16,17
In the HCSUS, the annual emergency department visit rate in the Medicaid population was 30% compared to 36% in this study. Additionally, the proportion of Medicaid patients hospitalized in 6 months was 25% compared to 29% over 1 year in this study.
One of our study objectives was to expose a large number of trainees to HIV-infected patients in the ambulatory setting. At the outset of the study, Duke residency training focused predominantly on inpatient care for the HIV-infected. Only a handful of residents cared for patients outside of the hospital. This is consistent with a nationwide survey of program directors in internal medicine that reported that the overwhelming majority of residents completed their training without ever caring for any HIV-infected patients in the ambulatory setting.4
By the conclusion of the study, 63 trainees had cared for ambulatory HIV-infected patients. Three quarters of these trainees provided care in GMC for all of the HIV-infected patients followed in GMC, whereas a small number of trainees in IDC provided care for 75% of the patients randomized to that group. Thus, we did expose a greater number of residents to direct patient care in GMC. Furthermore, when comparing measures of preventive and primary care, the residents in GMC provided remarkably good care, equal to that provided through the physicians with more experience in the IDC.
There are several important limitations to our study. Our study was performed in a single academic medical center in the context of a resident-run clinic. Another limitation relates to the ongoing rapid change in available treatment choices and standard of care. While we captured information on patterns of care during the transition to the era of highly active antiretroviral therapy (HAART), we do not have enough information to report on the usage of these agents. Despite these limitations, our study is the first in which care provided by generalist and specialist physicians for HIV-infected patients was compared in the setting of random allocation of patients to different primary care settings. We enrolled and randomized 89% of eligible patients who sought HIV-related primary care in our setting and had follow-up information on 93% of patients, which attests to high internal validity.
In summary, patients assigned to specialist clinic had significantly less use of hospital services than those patients assigned to generalist clinic. These differences are not explained by differences in the receipt of well-established components of evidence-based primary care such as PCP prophylaxis, screening for TB, and administration of pneumococcal vaccination. Even aspects of HIV care in which the standards were rapidly changing, such as antiretroviral use, were provided equally in the 2 groups. Some unmeasured aspect of physician experience in HIV care or structure of the clinics may account for these differences. Attaining the clinical goal of high quality care and limited use of expensive hospital services for HIV-infected patients may require a greater degree of subspecialty input or a restructuring of the support services of the clinic. The provision and retention of evidence-based interventions is not sufficient to achieve these two goals. In addition, the tension remains between the need to train physicians to become experienced clinicians in the care of HIV-infected patients and the need to reap the benefits of relying on already experienced clinicians to manage scarce resources in the current, cost-conscious health care environment.