WNV AVB 02212006

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West Nile neuroinvasive disease in hospitalized patients Amy V. Bode 2006 National Conference on West Nile Virus in the United States February 23-24, 2006 San Francisco, California

Background:: 

Background: Significant morbidity with all West Nile viral (WNV) illnesses Small portion of infected people develop encephalitis Risk factors for WNV encephalitis & prognosis of hospitalized patients still undefined Associated complications of encephalitis undefined but may add significant cost

Goals:: 

Goals: Identify risk factors (RFs) for encephalitis among hospitalized persons with WNV illness Describe outcome of index hospitalization Describe clinical complications among persons hospitalized with confirmed WNV illness Determine true cost of illness to discuss potential utility of a WNV vaccine

Previous studies of hospitalized persons:: 

Previous studies of hospitalized persons: Romania, 1996, Hahn et al.: Meningoencephalitis (ME) : Associated with more time outdoors Not significantly associated with hypertension, smoking, diabetes mellitus (DM), age nor gender New York City, 1999, Nash et al.: Case fatality ratio (CFR) 12% Death among persons with ME & muscle weakness associated with: Age ≥75 years (adjusted RR: 8.5 [1.2,59.1]) DM (age-adjusted RR: 5.1 [1.5,17.3])

Previous studies of hospitalized persons:: 

Previous studies of hospitalized persons: Louisiana, 2002, Sejvar et al.: Of 16 hospitalized persons with serologically-confirmed WNV neuro disease (5 meningitis; 8 encephalitis; 3 AFP) 15 (94%) had tremor 5 (31%) had myoclonus 11 (69%) had parkinsonism 1 died Ontario, 2002, Pepperell et al.: Of 57 WNV patients with encephalitis, 10 (18%) died Of 47 survivors, only 13 (28%) discharged without support

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Colorado, 2003: WNV Epicenter 4.6M residents; 64 counties 2,947 WNV illnesses 621 neuroinvasive illnesses 63 fatalities among neuroinvasive disease cases (CFR 10%)

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Colorado, 2003: WNV Epicenter Boulder, Denver, Larimer, & Weld Cos. 1.3M residents (~30% CO’s population) 1,531 WNV illnesses (~52% CO’s reported cases) 333 hospitalized with WNV illness

4-County Review, Colorado, 2003: 

4-County Review, Colorado, 2003 Large, population-based study; 333 hospitalized cases 4-County resident, confirmed WNV, hospitalized in 2003 Retrospective multi-hospital medical record review Assigned clinical syndrome Demographic information Past medical history & behaviors Hospital course Disposition Short-term outcome RFs for encephalitis, limb weakness & death

Results: Colorado, 2003: 

Results: Colorado, 2003 228 (69% of hospitalized persons) medical records reviewed 221 patients included 103 with West Nile meningitis (WNM) 65 with West Nile encephalitis (WNE) 53 with West Nile fever (WNF) 7 excluded 1 ADEM following SLE viral infection 6 without fever

Proportion of persons with specific West Nile viral syndromes: 

Proportion of persons with specific West Nile viral syndromes

Impact on hospitalization rates,4-Counties, Colorado, 2003: 

Impact on hospitalization rates, 4-Counties, Colorado, 2003 Projecting from 221 cases All WNV illnesses: 25 hospitalized / 105 population WNE: 7 hospitalized / 105 WNM: 12 hospitalized / 105 WNF: 6 hospitalized / 105

Results: Colorado, 2003: 

Results: Colorado, 2003 Risk factors for WNE compared to persons with WNF* Age – Adjusted OR (AOR): 1.04/year [1.01,1.07] Alcohol abuse – AOR: 7.5 [1.5, 37.8] Diabetes mellitus – AOR: 4.1 [1.2,13.6] Risk factors for limb weakness compared to those without weakness* Age – AOR: 1.02 per year [1.01,1.04] WNE - AOR: 3.2 [1.5, 6.5] *Backward & forward, stepwise logistic regression

Results: Colorado, 2003: 

Results: Colorado, 2003 Risk factors for death among persons with encephalitis compared to survivors* Age – AOR: 1.14 per year [1.02,1.29] Immunosuppression – AOR: 26.5 [3.0,234] Mechanical ventilation – AOR: 12.7 [1.2,139] History of stroke – AOR: 42.7 [2.4,756] *Backward & forward, stepwise logistic regression

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Despite syndrome, patients with limb weakness more likely to be intubated Bulbar dysfunction (brainstem encephalitis?) associated with respiratory failure WNE patients 4 times more likely to have bulbar dysfunction than WNM patients Who will need intubation & ventilation? Take-home: Persons with limb weakness and bulbar dysfunction (dysarthria, dysphagia) at high risk for respiratory failure despite attributed clinical syndrome

Complications by clinical syndrome: 

Complications by clinical syndrome * Excludes sinus bradycardia & tachycardia

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Disposition following index hospitalization by clinical syndrome

Conclusions :: 

Conclusions : Age is risk factor for encephalitis, limb weakness & death In addition: DM & history of alcohol abuse increase risk of WNE History of stroke, respiratory failure, or immunosuppression increase mortality among those with WNE WNE increases risk of limb weakness Respiratory failure, limb weakness, & arrhythmias occurred in WNE, WNM, & WNF but more so in WNE Limb weakness & bulbar dysfunction – Watch for respiratory failure

Acknowledgments:: 

Acknowledgments: Roy Campbell Jim Sejvar John Pape Anthony Marfin Jen Lehman Krista Kniss Peggy Collins Stephanie Kuhn Laura Polakowski David Berndt Many Infection Control practitioners, Infectious Disease subspecialists, Neurology subspecialists of Weld, Larimer, Boulder and Denver counties, Colorado