Role Of Obesity In Severe H1N1 Infections
A report led by doctors from the University of Michigan Health System documents severe lung problems among patients infected with the influenza A H1N1 (swine) flu virus, and suggests that obesity may be emerging as a new risk factor in the pandemic.
A high proportion of patients with H1N1 flu and pneumonia or a serious lung condition called acute respiratory distress syndrome who were cared for in the U-M Surgical Intensive Care Unit were obese or extremely obese, according to the U-M report. It appears as a special dispatch in the U.S. Centers for Disease Control and Prevention’s publication Morbidity and Mortality Weekly Report.
Out of a series of 10 patients, nine of them were obese, with a body mass index over 30. Seven of those were extremely obese, with a BMI over 40.
Obesity alone is not considered a risk factor for regular seasonal flu. The high prevalence of obesity among the H1N1 patients is striking, according to the report.
“Most of the patients had no other illness that would make them prone to advanced viral infection and ARDS,” says lead author Lena Napolitano, M.D., who is chief of the Division of Acute Care Surgery, director of surgical critical care, and associate chair for critical care in the U-M Department of Surgery.
Three of the patients died. Two out of the three patients who died had no other health problems.
The median age of patients in the report was 46; the youngest was 21 years old. Only three of the 10 patients had known risk factors (such as advanced age, pregnancy, or a chronic health problem like asthma or heart problems) which might make them more vulnerable to complications from seasonal flu.
The report also describes the treatment provided at U-M, which is a regional center for ARDS care. Because some of the patients were transferred to U-M from other hospitals, the authors estimate that on average the patients had started receiving antiviral medications eight days after their illness began.
A significant complication seen in the patients who had severe pneumonia in both lungs due to their H1N1 infection was pulmonary emboli, or blood clots in the lungs.
Clinicians should be aware of the potential for severe complications of H1NI, particularly in extremely obese patients, say the authors, who also include members of the CDC flu response team, the Michigan Department of Community Health and the U-M School of Public Health.
“What we found -- patients with severe ARDS, associated pulmonary emboli and high prevalence of obesity -- suggests a new focus for community hospitals which are the first line providers in caring for potential H1N1 flu patients,” Napolitano says. “When doctors see obese patients with acutely worsening upper respiratory infection symptoms, they should consider the possibility of H1N1 viral pneumonia and initiate early appropriate empiric antiviral medications.”
The U-M Surgical Intensive Care Unit’s team, which includes expert physicians, nurses, respiratory therapists, and other health care providers, specializes in caring for patients with ARDS.
As a result, in recent weeks, a number of severely ill H1N1 patients from around Michigan and the upper Midwest have been transferred to U-M, most by the Health System’s nationally-acclaimed Survival Flight air ambulance service. Community hospitals throughout Michigan have played a significant role in the care of these patients both prior to transfer, and in ongoing management of the patients’ care after their clinical condition stabilized.
As of early July, the United States has more than 37,000 confirmed cases of H1N1 flu and the number of deaths has risen to 211. But it’s estimated that far more – perhaps more than 1 million Americans – may have experienced mild disease and not been treated for it. In Michigan, there have been 489 cases reported and eight deaths, according to the CDC.
The report from U-M raises questions about what role obesity –– a growing societal concern, with one-third of Americans weighing too much – may play in the lingering worldwide H1N1 flu pandemic. Obesity is a risk factor for cardiovascular diseases, Type 2 diabetes, some cancers and sleep problems. While this preliminary report could not draw definitive conclusions about the connection between obesity and complications from H1N1 flu, additional research will be required to address this important issue.
Health officials are continuing to remind the public about the importance of handwashing and good hygiene to prevent H1N1 flu, which are also good prevention measures for seasonal flu. And hospitals everywhere, including UMHS, are preparing for a likely surge in H1N1 cases during the regular 2009-2010 flu season, which begins in October.