Clinical Findings and Demographic Factors Associated With ICU Admission in Utah Due to Novel 2009 Influenza A(H1N1) Infection

Chest. 2010 Apr;137(4):752-8. doi: 10.1378/chest.09-2517. Epub 2009 Nov 20.

Abstract

Background: Novel 2009 influenza A(H1N1) infection has significantly affected ICUs. We sought to characterize our region's clinical findings and demographic associations with ICU admission due to novel A(H1N1).

Methods: We conducted an observational study from May 19, 2009, to June 30, 2009, of descriptive clinical course, inpatient mortality, financial data, and demographic characteristics of an ICU cohort. A case-control study was used to compare the ICU cohort to Salt Lake County residents.

Results: The ICU cohort of 47 influenza patients had a median age of 34 years, Acute Physiology and Chronic Health Evaluation II score of 21, and BMI of 35 kg/m2. Mortality was 17% (8/47). All eight deaths occurred among the 64% of patients (n = 30) with ARDS, 26 (87%) of whom also developed multiorgan failure. Compared with the Salt Lake County population, patients with novel A(H1N1) were more likely to be obese (22% vs 74%; P < .001), medically uninsured (14% vs 45%; P < .001), and Hispanic (13% vs 23%; P < .01) or Pacific Islander (1% vs 26%; P < .001). Observed ICU admissions were 15-fold greater than expected for those with BMI > or = 40 kg/m2 (standardized morbidity ratio 15.8, 95% CI, 8.3-23.4) and 1.5-fold greater than expected among those with BMI of 30 to 39 kg/m(2) for age-adjusted and sex-adjusted rates for Salt Lake County.

Conclusions: Severe ARDS with multiorgan dysfunction in the absence of bacterial infection was a common clinical presentation. In this cohort, young nonwhites without medical insurance were disproportionately likely to require ICU care. Obese patients were particularly susceptible to critical illness due to novel A(H1N1) infection.

MeSH terms

  • Adolescent
  • Adult
  • Case-Control Studies
  • Critical Illness / epidemiology
  • Disease Progression
  • Female
  • Hospital Mortality
  • Humans
  • Incidence
  • Influenza A Virus, H1N1 Subtype*
  • Influenza, Human / complications*
  • Influenza, Human / epidemiology
  • Influenza, Human / therapy*
  • Intensive Care Units / statistics & numerical data*
  • Male
  • Middle Aged
  • Multiple Organ Failure / epidemiology
  • Multiple Organ Failure / therapy*
  • Multiple Organ Failure / virology
  • Respiratory Distress Syndrome, Adult / epidemiology
  • Respiratory Distress Syndrome, Adult / therapy*
  • Respiratory Distress Syndrome, Adult / virology
  • Risk Factors
  • Socioeconomic Factors
  • Utah / epidemiology
  • Young Adult