Journal Watch: Recent studies of note

Recent studies about ventilator allocation in disasters, MRSA screening, and other topics.

New York state drafts guide for ventilator allocation in disasters

The New York State Workgroup on Ventilator Allocation in an Influenza Pandemic has published its recommendations for ventilator allocation during a public health disaster.

The workgroup set out to develop guidelines for deciding how ventilators would be allocated during a disaster situation in which the number of patients who need ventilators exceeds ventilator supply. Workgroup members developed an ethical framework that took into account duty to care, duty to steward resources, duty to plan, distributive justice and transparency. The draft guidelines, which are thought to be the first of their kind in the U.S., include the following elements:

  • Pretriage requirements. Before rationing begins, facilities should limit noncritical ventilator use and postpone or cancel all elective procedures, among other measures.
  • Patient categories. Any rationing system should be applied to all hospitalized patients requiring critical care rather than specific categories of patients.
  • Acute versus chronic care facilities. Patients in chronic care facilities should not be subject to triage guidelines used in acute care facilities.
  • Clinical evaluation. The clinical evaluation should use exclusion criteria (such as cardiac arrest and metastatic malignancy with poor prognosis), Sequential Organ Failure Assessment (SOFA) score, and time trials (to determine which patients are benefiting from ventilator use).
  • Triage decision makers. Clinicians would not be the sole decision makers about ventilator allocation but would instead consult with a triage officer.
  • Palliative care. Palliative care should be provided for all patients who do not receive or are removed from ventilators due to triage decisions.
  • Review of triage decisions. Although real-time review is not feasible in a crisis, all triage decisions should be retrospectively reviewed daily to ensure that standards are being met.
  • Communication. Health officials and political leaders must communicate to the public that standards of care change in a disaster situation, while physicians and staff must be prepared to discuss ventilator allocation with patients and families.

The guidelines appeared in the March issue of Disaster Medicine and Public Health Preparedness. The workgroup has invited public comment on the guidelines and plans to review, clarify and revise them as needed. The process used to develop these guidelines could be used as a template for allocation of other scarce resources during a public health emergency, the workgroup authors wrote.

Studies on MRSA screening yield conflicting results

Two studies on screening for methicillin-resistant Staphylococcus aureus (MRSA) recently reported different results, with one study finding that universal screening did not reduce infection rates and one finding that it did.

In the first study, researchers at a Swiss hospital used a crossover design to study the effects of rapid MRSA screening at admission in a cohort of 21,754 surgical patients. Patients underwent rapid screening before or at admission followed by standard infection control measures (10,844 patients) or received standard infection control measures alone (10,910 patients). The results appeared in the March 12 Journal of the American Medical Association.

During the intervention periods, 515 patients (5.1%) were identified as being MRSA-positive. Nosocomial MRSA infection developed in 93 patients during the intervention periods versus 76 patients during the control periods (adjusted incidence rate ratio, 1.20 [95% CI, 0.85 to 1.69]; P= 0.29). No significant change was seen in rates of nosocomial MRSA acquisition or MRSA surgical site infection.

The authors offered several explanations for their results, including comparatively low rates of MRSA infection overall at their facility, postoperative transmission, delays in receipt of test results and inadequate use of prophylaxis. They also noted limitations in their study design, such as the inability to randomize wards to a specific intervention. However, the authors concluded that active surveillance may not be enough to reduce rates of surgical site infection and nosocomial MRSA transmission. The authors, and the accompanying editorialists, recommended that hospitals consider local MRSA infection patterns before implementing universal screening. The editorialists also pointed out that MRSA infections account for only 8% of nosocomial infections in the U.S. and stressed the importance of interventions that address all of these types of infections.

In the second study, researchers in Illinois implemented a three-year program to compare three strategies for combating MRSA: no screening, screening those admitted to the emergency departments and screening all people admitted to the hospital (universal surveillance). The study involved three hospitals with a total of 850 beds and approximately 40,000 annual admissions. Universal surveillance was associated with a reduction by more than half of nosocomial bloodstream, respiratory, urinary tract and surgical site MRSA infection occurring during the hospital stay and in the 30 days after discharge. The study was published in the March 18 Annals of Internal Medicine.

An editorial writer noted that the rapid polymerase chain reaction (PCR)-based test used in the universal screening phase of the study was not used in the first two phases and thus could skew results. Further, the PCR-based test costs about $25 to $30 compared to the $5 standard culture lab test, so screening all patients with the fast test may have an economic impact on the hospital. The writer suggested that a strategy of targeting high-risk populations for screening, such as nursing home residents, would be a more cost-effective way to confront MRSA infection. “The one-size-fits-all approach is probably not sensible for MRSA screening,” he wrote.

Older blood may lead to worse outcomes after cardiac surgery

Cardiac surgery patients who receive transfusions of blood stored for more than two weeks may have worse outcomes than those who receive newer blood, according to a study.

Previous research has suggested that complications after transfusions are more likely if transfused blood has been stored for long periods, possibly because structural and functional changes during storage decrease red-cell viability. Researchers at the Cleveland Clinic Foundation performed an observational cohort study to compare complication and mortality rates in patients who received transfusions with newer blood (stored for 14 days or less) and older blood (stored for more than 14 days) during cardiac surgery. Included patients were 18 years of age or older and had undergone coronary artery bypass grafting, cardiac valve surgery or both at the Cleveland Clinic from June 30, 1998 to January 30, 2006. The study results appeared in the March 20 New England Journal of Medicine.

Overall, 2,872 patients received 8,802 units of newer blood and 3,130 patients received 10,782 units of older blood during the defined time period. Median blood storage time was 11 days for newer blood versus 20 days for older blood. Patients who received older blood had higher rates of in-hospital mortality, renal failure, longer-term intubation and sepsis or septicemia than patients who received newer blood and were more likely to develop multiple serious adverse events. One-year mortality rates were also higher in patients who received older blood (11.0% vs. 7.4%; P< 0.001).

The authors concluded that transfusions of blood stored for more than two weeks are associated with poorer outcomes after cardiac surgery. However, they noted that more research is necessary before blood banking procedures and practices can be changed based on their study results. An accompanying editorial called the study's outcome important but noted that it “simply adds an important piece to the discussion of the risks of transfusion” and does not define best practice. Both the authors and the editorialist pointed to the difficulties inherent in shortening blood storage time, including restriction of the overall blood supply, while the editorialist stressed the importance of blood management and conservation programs to help decrease blood consumption.

Minorities and whites receive similar-quality care within hospitals, study finds

Whites and ethnic minorities receive similar-quality care when admitted to the same hospital for the same conditions or procedures, a recent study reported.

Researchers used three years' worth of data from inpatient discharges in 13 states to determine hospital-specific quality measures according to race and ethnicity (whites, blacks, Hispanics and Asians). Quality indicators were taken from the Agency for Healthcare Research and Quality and looked at quality of inpatient care and patient safety, including mortality rates for four inpatient procedures (e.g., abdominal aortic aneurysm repair and coronary artery bypass graft), six inpatient conditions (e.g., acute myocardial infarction and acute stroke) and 15 patient safety indicators (e.g., decubitus ulcer and postoperative sepsis). The results appear in the March/April Health Affairs.

Disparities in quality of care were noted when overall risk-adjusted rates of mortality and adverse events were compared by race and ethnicity. For example, the risk-adjusted mortality rate for abdominal aortic aneurysm was lowest for whites and highest for blacks (0.0335 vs. 0.0381). However, in comparisons within hospitals, risk-adjusted quality indicators did not differ statistically by ethnicity and race, and only a small number of hospitals provided lower-quality care to minorities than to whites and vice versa, the authors found.

The authors noted that their study examined patients who received care and did not address disparities in care access. They also acknowledged several study limitations, including the lack of data from any West Coast states with large Asian populations and the fact that AHRQ indicators do not reflect outpatient settings. However, the authors wrote, their findings suggest that within specific hospitals, minorities and white patients generally receive the same quality of care. Policymakers should direct quality improvement efforts toward lower-performing hospitals rather than all hospitals, the authors concluded.

Urine test may help prevent kidney damage after surgery

A simple urine test can identify which patients may suffer kidney damage following surgery much sooner than the problem would be detected otherwise, according to a recent pilot study.

The study looked at 196 children who underwent cardiopulmonary bypass during surgery to repair congenital heart defects. Acute kidney injury (AKI) occurred in 51% of the children, diagnosed based on increased levels of creatinine two to three days after surgery.

Researchers found that, in the patients who developed AKI, levels of neutrophil gelatinase-associated lipocalin (NGAL)—a predictor of acute kidney injury—were 15 times higher than normal within two hours after surgery. In contrast, detectable increases in serum creatinine can take up to three days. The study was released early online and appears in the May 2008 Journal of the American Society of Nephrology.

Researchers noted that early detection of NGAL would enable physicians to shift clinical management of patients early enough to potentially prevent development of AKI, said a March 12 ASN news release. In the study, NGAL levels at two hours following surgery identified 90% of children who later developed AKI, and children with higher NGAL levels were more likely to require dialysis, more likely to die, and took longer to recover kidney function.

The study received funding from Abbott, which is developing the NGAL test. More research on different groups of patients is needed to confirm the value of using NGAL as a biomarker to identify AKI, said the ASN release.