Clincal Briefs

By Louis Kuritzky, MD

Effects of Influenza Vaccination of Health Care Workers on Mortality of Elderly People in Long-Term Care: A Randomized Controlled Trial

Most of the excess mortality from influenza occurs in persons older than 65 years of age. Even though vaccination of senior citizens, especially in long-term care facilities, does reduce mortal complications of influenza, incomplete vaccination rates and poor immune response result in spotty coverage of this at-risk population. Influenza in health care workers, as manifest by seroconversion, occurs in as many as 23% of hospital staff, and may be a source of transmission of influenza virus to seniors. A pilot study in which health care worker vaccination was evaluated demonstrated a 41% reduction in elderly mortality from influenza, prompting this more definitive trial.

Twenty U.K. hospitals participated in this trial—only half of which offered immunization to their health care workers (n = 1217). Randomized patients were also equally divided among the 10 hospitals that used influenza immunization and 10 that did not (n = 1437).

Only 50% of health care workers accepted the offered influenza immunization. Nonetheless, the senior mortality in the immunization-offered health care worker sites was 42% lower than in the nonimmunized sites. Although, for inexplicable reasons, the background immunization level of the elderly patients in the immunization-offered sites was slightly higher than the other sites, this variance is insufficient to account for the mortality benefits seen as a result of health care worker immunization.

Carman WF, et al. Lancet 2000; 355:93-97.

Hyperinsulinemia, Hyperglycemia, and Impaired Hemostasis

Only about half of the in-creased risk for cardiovascular mortality observed in patients with diabetes is accounted for by traditional risk factors. Insulin resistance (IR) and hyperinsulinemia (HI) have been suggested as factors to which additional cardiovascular morbidity and mortality are attributable. The mechanism(s) by which IR and HI negatively affect cardiovascular health remain to some degree speculative, but a role in modulation of coagulation status has been suggested. Meigs and colleagues evaluated a subgroup (n = 1331) of the Framingham Study population to test the hypothesis that altered glucose tolerance and insulin resistance would be associated with increased hemostatic factor levels, independent of other factors like obesity and lipids.

Hypercoagulability has been associated with increased levels of fibrinogen, factor VII, and von Willebrand factor; decreased fibrinolytic potential has been associated with increased plasminogen activator inhibitor 1 (PAI-1) antigen, or tissue-type plasminogen activator (tPA) antigen.

In this study, fasting hyperinsulinemia was associated with increased levels of PAI-1 antigen, tPA antigen, factor VII antigen, von Willebrand factor antigen, fibrinogen, and blood viscosity. Additionally, it has been suggested that elevated levels of PAI-1 predispose to low-stability plaque formation. Meigs et al comment that the atherogenic effects of glucose and insulin abnormalities seen in diabetes may be mediated through aberrations in hemostatic factors.

Meigs JB, et al. JAMA 2000;283: 221-228.

Primary Care Outcomes in Patients Treated by Nurse Practitioners or Physicians

Assessment of outcomes for patients seen by different providers has been hampered by differences in practice patterns, populations, and responsibilities of clinicians in different settings. This study draws from a New York clinical setting staffed by nurse practitioners in some sites and physicians in others, where 24-hour ambulatory care is provided by both providers to a population predominantly of Hispanic origin (Dominican Republic). The work responsibilities, including opportunity for consultation, referral, and hospitalization, were the same. Patients with asthma, diabetes, and hypertension were selected for audit, since they were felt to represent a cohort in which outcomes might be reliably monitored (n = 1316 enrolled).

Overall patient satisfaction was the same for both groups. Overall health status improved over the duration of the study and was equal for both groups. Asthma and diabetic control was equal for both groups, but nurse practitioner care achieved significantly better diastolic blood pressure control than physicians. No differences were found in health care service utilization between providers. Though statistically significant, a clinically insignificant difference in patient ratings of technical skill, personal manner, and time spent was found in favor of physicians. These data suggest that nurse practitioner and physician outcomes in primary care settings are equivalent.

Mundinger MO, et al. JAMA 2000; 283:59-68.