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Original Research |

Prognosis after West Nile Virus Infection

Mark Loeb, MD, MSc; Steven Hanna, PhD; Lindsay Nicolle, MD; John Eyles, PhD; Susan Elliott, PhD; Michel Rathbone, MD; Michael Drebot, PhD; Binod Neupane, MSc; Margaret Fearon, MD; and James Mahony, PhD
[+] Article, Author, and Disclosure Information

From McMaster University, Hamilton, Ontario; University of Manitoba and the Public Health Agency of Canada, Winnipeg, Manitoba; and Ontario Provincial Laboratory, Toronto, Ontario, Canada.

Grant Support: Funded by the Canadian Institutes of Health Research (grant no. 69010).

Potential Financial Conflicts of Interest: None disclosed.

Reproducible Research Statement:Study protocol and data set: Not available. Statistical code: The code for the nonlinear mixed-effects modeling is available from Dr. Hanna (e-mail, hannas@mcmaster.ca).

Requests for Single Reprints: Mark Loeb, MD, MSc, McMaster University, MDCL 3200, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada; e-mail, loebm@mcmaster.ca.

Current Author Addresses: Dr. Loeb and Mr. Neupane: McMaster University, MDCL 3200, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.

Dr. Hanna: McMaster University, 1400 Main Street West, CE&B, IAHS Building, Room 408, Hamilton, Ontario L8S 1C7, Canada.

Dr. Nicolle: University of Manitoba, GG443-820 Sherbrook Street, Winnipeg, Manitoba R3N 0A3, Canada.

Dr. Eyles: McMaster University, 1280 Main Street West, General Sciences Building, Room 217, Hamilton, Ontario L8S 4K1, Canada.

Dr. Elliott: McMaster University, 1280 Main Street West, General Science Building, Room 229, Hamilton, Ontario L8S 4M4, Canada.

Dr. Rathbone: McMaster University/Henderson Hospital, 711 Concession Street, 70 Wing, Ground Floor, Room 23, Hamilton, Ontario L8V 1C3, Canada.

Dr. Drebot: National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada.

Dr. Fearon: Canadian Blood Services, 87 College Street, Toronto, Ontario M5G 2M1, Canada.

Dr. Mahony: St. Joseph's Healthcare, 50 Charlton Avenue East, Luke Wing, Room 424, Hamilton, Ontario L8N 4A6, Canada.

Author Contributions: Conception and design: M. Loeb, S. Hanna, S. Elliott, J. Mahony, M. Rathbone.

Analysis and interpretation of the data: M. Loeb, S. Hanna, B. Neupane, M. Rathbone, M. Drebot.

Drafting of the article: M. Loeb, S. Hanna, M. Drebot.

Critical revision of the article for important intellectual content: M. Loeb, S. Hanna, J. Eyles, S. Elliott, J. Mahony, M. Rathbone, M. Drebot.

Final approval of the article: M. Loeb, S. Hanna, L. Nicolle, J. Eyles, J. Mahony, M. Rathbone, M. Drebot.

Provision of study materials or patients: M. Loeb, L. Nicolle, M. Drebot.

Statistical expertise: M. Loeb, S. Hanna, B. Neupane.

Obtaining of funding: M. Loeb, S. Hanna, J. Mahony.

Administrative, technical, or logistic support: M. Loeb, M. Fearon, J. Mahony.

Collection and assembly of data: M. Loeb, L. Nicolle.

Ann Intern Med. 2008;149(4):232-241. doi:10.7326/0003-4819-149-4-200808190-00004
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Figure 1 illustrates the flow of study participants at different measurement dates. Of 367 participants, 156 (42.5%) were enrolled in the study (mean age, 52.0 years [SD, 13.5]; age range, 19 to 85 years; 76 [48.7%] women) (Table 1). Reasons for nonenrollment varied (patients did not call the study office back after receiving information [n = 71]; physicians could not be contacted or declined to contact the patient [n = 63]; patients declined participation [n = 38], did not meet eligibility criteria [n = 25], or died before enrollment [n = 7]; or the local hospital institutional review board approval could not be obtained in time [n = 7]). Age (52.0 years vs. 51.4 years; P = 0.73) or sex (49% men vs. 56% women; P = 0.22) did not significantly differ between enrolled and nonenrolled participants on the basis of the 45% of nonenrolled participants for whom demographic information was available.

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Figure 1.
Study flow diagram.

ICU = intensive care unit.

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Figure 2.
Predicted average recovery of Short Form-36 (SF-36) Physical Component Summary scores, SF-36 Mental Component Summary scores, Depression Anxiety Stress Scale scores, and Fatigue Severity Scale scores for neuroinvasive and nonneuroinvasive disease (left) and encephalitis and meningoencephalitis (right).
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Figure 3.
Kaplan–Meier curve of Short Form-36 Physical Component Summary (PCS) scores, stratified by comorbid condition.
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Figure 4.
Kaplan–Meier curves of Short Form-36 Mental Component Summary (MCS) scores, stratified by sex (top) and comorbid condition (bottom).
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Submit a Comment/Letter
Prognosis for West Nile Virus not as good as reported.
Posted on September 30, 2008
Don R. Read
Conflict of Interest: None Declared

In the August issue of Annals of Internal Medicine, Dr, Mark Loeb, et al. produced an elegant study, "Prognosis after West Nile Virus Infection". The conclusion suggests that everyone with West Nile Virus, even the neuroinvasive type, will completely recover within one year. The results of this study have received widespread media attention. Unfortunately, the conclusion is not supported by the data and is misleading. This misleading conclusion is detrimental to our public health efforts to educate the public about the dangers of West Nile Virus and about why they should try to prevent getting mosquito bites.

As a survivor of West Nile Virus neuroinvasive disease, I run a support group for West Nile Virus victims in Dallas, Texas. Obviously, a support group represents a self-selected group of patients who have not had a good outcome. Nevertheless, we have many members who have lingering problems of extreme fatigue, cognitive delay, persistent muscle weakness from polio-like paralysis, balance problems, and/or muscle pain, even after two to four years. In this self-selected cohort of patients, it is certainly not true that everyone returned to normal within 12 months.

In Dr. Loeb's cohort of patients it is also not true that everyone returned to normal in 12 months. He specifically excluded the seven patients who died before enrollment (a 1.9% mortality rate), the three patients who died between 30 days and 24 months, and the seven patients with acute flaccid paralysis (4% of the cohort). One patient was excluded at day 30 because the patient was on a ventilator, which is the hallmark of the severest form of West Nile Virus.

A better conclusion from the data would be that most people recover from West Nile Virus and that those who are going to recover completely do so within one year.

Dr. Loeb's research into West Nile Virus is a critical step forward in our understanding of the short term outcome from the disease. More work is needed in looking at the long term outcomes.

Conflict of Interest:

None declared

Submit a Comment/Letter

Summary for Patients

Do People With West Nile Virus Infection Eventually Return to Normal Health?

The summary below is from the full report titled “Prognosis after West Nile Virus Infection.” It is in the 19 August 2008 issue of Annals of Internal Medicine (volume 149, pages 232-241). The authors are M. Loeb, S. Hanna, L. Nicolle, J. Eyles, S. Elliott, M. Rathbone, M. Drebot, B. Neupane, M. Fearon, and J. Mahony.


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