Hospital volume and the outcomes of mechanical ventilation.

BACKGROUND An increased volume of patients is associated with improved survival in numerous high-risk medical and surgical conditions. The relationship between the number of patients admitted (hospital volume) and outcome among patients with critical illnesses is unknown. METHODS We analyzed data from 20,241 nonsurgical patients receiving mechanical ventilation at 37 acute care hospitals in the Acute Physiology and Chronic Health Evaluation clinical information system from 2002 through 2003. Multivariate analyses were performed to adjust for the severity of illness and other differences in the case mix. RESULTS An increase in hospital volume was associated with improved survival among patients receiving mechanical ventilation in the intensive care unit (ICU) and in the hospital. Admission to a hospital in the highest quartile according to volume (i.e., >400 patients receiving mechanical ventilation per year) was associated with a 37 percent reduction in the adjusted odds of death in the ICU as compared with admission to hospitals in the lowest quartile (< or =150 patients receiving mechanical ventilation per year, P<0.001). In-hospital mortality was similarly reduced (adjusted odds ratio, 0.66; 95 percent confidence interval, 0.52 to 0.83; P<0.001). A typical patient in a hospital in a low-volume quartile would have an adjusted in-hospital mortality of 34.2 percent as compared with 25.5 percent in a hospital in a high-volume quartile. Among survivors, there were no significant trends in the length of stay in the ICU or the hospital. CONCLUSIONS Mechanical ventilation of patients in a hospital with a high case volume is associated with reduced mortality. Further research is needed to determine the mechanism of the relationship between volume and outcome among patients with a critical illness.

[1]  P Royston,et al.  The use of fractional polynomials to model continuous risk variables in epidemiology. , 1999, International journal of epidemiology.

[2]  David W Baker,et al.  The Effect of Publicly Reporting Hospital Performance on Market Share and Risk-Adjusted Mortality at High-Mortality Hospitals , 2003, Medical care.

[3]  Rodney A Hayward,et al.  Accepting Critically Ill Transfer Patients: Adverse Effect on a Referral Center's Outcome and Benchmark Measures , 2003, Annals of Internal Medicine.

[4]  H. Luft,et al.  The volume-outcome relationship: practice-makes-perfect or selective-referral patterns? , 1987, Health services research.

[5]  S. Lemeshow,et al.  Patient characteristics and ICU organizational factors that influence frequency of pulmonary artery catheterization. , 2000, JAMA.

[6]  W. Carlo,et al.  Mortality in low birth weight infants according to level of neonatal care at hospital of birth. , 2002, Pediatrics.

[7]  Ethan A Halm,et al.  Is Volume Related to Outcome in Health Care? A Systematic Review and Methodologic Critique of the Literature , 2002, Annals of Internal Medicine.

[8]  C. Behrendt.  Acute respiratory failure in the United States: incidence and 31-day survival. , 2000, Chest.

[9]  L A Mularz,et al.  Caring for Ventilator‐Dependent Patients , 1989, Nursing management.

[10]  The association between hospital volume and survival after acute myocardial infarction in elderly patients. , 1999 .

[11]  W. Knaus,et al.  The APACHE III prognostic system. Risk prediction of hospital mortality for critically ill hospitalized adults. , 1991, Chest.

[12]  A Milstein,et al.  Improving the safety of health care: the leapfrog initiative. , 2000, Effective clinical practice : ECP.

[13]  J. Escarce,et al.  Admission source to the medical intensive care unit predicts hospital death independent of APACHE II score. , 1990, JAMA.

[14]  Edward L. Hannan,et al.  Investigation of the Relationship Between Volume and Mortality for Surgical Procedures Performed in New York State Hospitals , 1989 .

[15]  G. V. Berghe,et al.  Intensive insulin therapy in critically ill patients. , 2001, The New England journal of medicine.

[16]  G Sherman,et al.  Effect of a nursing-implemented sedation protocol on the duration of mechanical ventilation. , 1999, Critical care medicine.

[17]  M Schetz,et al.  Intensive insulin therapy in critically ill patients. , 2001, The New England journal of medicine.

[18]  W. Knaus,et al.  Variations in Mortality and Length of Stay in Intensive Care Units , 1993, Annals of Internal Medicine.

[19]  Valerie J. Gooder,et al.  The impact of a multidisciplinary approach on caring for ventilator-dependent patients. , 1998, International journal for quality in health care : journal of the International Society for Quality in Health Care.

[20]  Salvador Benito,et al.  Characteristics and outcomes in adult patients receiving mechanical ventilation: a 28-day international study. , 2002, JAMA.

[21]  S. Wedel,et al.  Regionalization of critical care medicine: Task force report of the American College of Critical Care Medicine , 1994, Critical care medicine.

[22]  D. Schoenfeld,et al.  Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. , 2000, The New England journal of medicine.

[23]  W. Sibbald,et al.  Acute respiratory failure , 1976, Critical care medicine.

[24]  C. Begg,et al.  The influence of hospital volume on survival after resection for lung cancer. , 2001, The New England journal of medicine.

[25]  J. Sampalis,et al.  Trauma care regionalization: a process-outcome evaluation. , 1999, The Journal of trauma.

[26]  Chuntao Wu,et al.  Do Hospitals and Surgeons With Higher Coronary Artery Bypass Graft Surgery Volumes Still Have Lower Risk-Adjusted Mortality Rates? , 2003, Circulation.

[27]  V. Stone,et al.  The relation between hospital experience and mortality for patients with AIDS. , 1992, JAMA.

[28]  E. Mackenzie,et al.  Relationship between trauma center volume and outcomes. , 2001, JAMA.

[29]  J. Birkmeyer,et al.  Volume standards for high-risk surgical procedures: potential benefits of the Leapfrog initiative. , 2001, Surgery.

[30]  J. Jones,et al.  Is there a Relationship between the Volume of Work Carried Out in Intensive Care and its Outcome? , 1995, International Journal of Technology Assessment in Health Care.

[31]  Peter J Pronovost,et al.  Physician staffing patterns and clinical outcomes in critically ill patients: a systematic review. , 2002, JAMA.

[32]  K Y Liang,et al.  Longitudinal data analysis for discrete and continuous outcomes. , 1986, Biometrics.

[33]  C. Begg,et al.  Impact of hospital volume on operative mortality for major cancer surgery. , 1998, JAMA.

[34]  Diane P. Martin,et al.  Incidence and outcomes of acute lung injury. , 2005, The New England journal of medicine.

[35]  E F Haponik,et al.  Effect on the duration of mechanical ventilation of identifying patients capable of breathing spontaneously. , 1996, The New England journal of medicine.

[36]  D. Angus,et al.  Improving care of the critically ill: institutional and health-care system approaches , 2004, The Lancet.

[37]  J. Torner,et al.  Hospital volume-outcome relationships among medical admissions to ICUs. , 2005, Chest.

[38]  W. Tarnow-Mordi,et al.  Hospital mortality in relation to staff workload: a 4-year study in an adult intensive-care unit , 2000, The Lancet.

[39]  T. Clemmer,et al.  Descriptive analysis of critical care units in the United States , 1992, Critical care medicine.