Pertussis incidence among adults may be underreported

The incidence of pertussis, also known as whooping cough, among adults aged 50 and up may be vastly underreported and under-recognized, according to a study recently conducted by research-based pharmaceutical company GlaxoSmithKline.

The GSK researchers analyzed approximately 48 million cases of cough-related illness in the U.S. with a multiple linear regression to determine that there were approximately 520,000 cases of pertussis in the U.S. between 2006 and 2010 among adults aged 50 to 64. This was much higher than the medically-attended 8,764 cases that were reported at the time.

The study also found that there were approximately 465,000 cases of pertussis among adults 65 and older versus the 6,539 medically-attended cases of pertussis that were reported between 2006 and 2010.

"The (U.S. Centers for Disease Control and Prevention), other public health authorities and infectious disease experts have long suspected that pertussis cases in adults go undetected or are misdiagnosed as other respiratory ailments," Leonard Friedland, the vice president and director of scientific affairs and public health for GSK Vaccines, said. "To our knowledge, this is the first attempt to quantify the incidence of cough illness attributed to B. pertussis via regression modeling among those greater than 50 years old."

According to the CDC, there were 48,277 cases of pertussis reported in the U.S. in 2012, the highest number reported since 1955.

"The authors plan to share their research methods and welcome other researchers to further examine and build upon the findings of this study," Friedland said. "These findings suggest a major need for healthcare providers to consider the possibility of pertussis in older patients they see who have respiratory symptoms."

GSK noted the results of the study should be interpreted in the context of its limitations. The study used claims data, which are collected for reimbursement and billing purposes rather than for research.