Researchers found healthy adults who self-rated poorer health were more likely to develop a common cold than those who self-rated better health.
Published in the journal Psychosomatic Medicine, the study found that healthy individuals who rated their health as excellent were less likely to have poorer immune system function and were less susceptible to the common cold, compared with those whose self-rated heath was lower.
According to study co-author Sheldon Cohen, of the Dietrich College of Humanities and Social Sciences at Carnegie Mellon University in Pittsburgh, PA, previous research has indicated that self-ratings of poor health are predictors of poor health in older adults.
"Strikingly," Cohen adds, "these associations remain significant even after accounting for the effects of objective indicators of health such as physical exams, medical records and hospitalizations."
It has been suggested that such an association may be because people tend to judge themselves as healthier if they engage in a healthier lifestyle or if they have better emotional well-being, and such people are less likely to become ill.
In this latest study, Cohen and colleagues set out to investigate whether self-ratings of health among younger, healthy adults could predict immune response, and whether the results could be explained by socioemotional factors or lifestyle.
Subjects with lower-rated health more likely to develop a cold
The team asked 360 healthy adults of an average age of 33 to assess their health as "poor," "fair," "good," "very good" or "excellent."
Only 2% of participants reported their health as fair, and none of the subjects reported poor health. The researchers say this was to be expected since the study enrolled healthy adults.
The participants were then exposed to a common cold virus and monitored for 5 days to see if they developed the illness. This was to test their immune response. Around a third of participants developed a cold.
Compared with participants who rated their health as excellent, those who rated their health as fair, good or very good were more than two times as likely to develop a cold, according to the results.
Not only were the results independent of participants' age, sex, race, body mass index (BMI), education and income, the team found that they could not be explained by subjects' health practices and socioemotional factors.
Further investigation revealed the findings were also independent of participants' history of having common colds.
The researchers believe their results may possibly be explained by "pre-morbid indicators" of immune system dysfunction, such as feelings or sensations that something is wrong.
As such, the team says doctors should ask patients to rate their own health, as they may be onto something. Cohen adds:
"There are some things that we know about our bodies that aren't easily detectable by our physicians. Our data suggest that this evaluation reflects how the immune system reacts to infectious agents."
In an editorial linked to the study, Hyong Jin Cho and colleagues, from the School of Medicine at the University of California-Los Angeles, say the research represents a "unique contribution to the understanding of biological mechanisms of the link between self-rated health and morbidity."
They note, however, that further research is required to determine whether the findings may be translational to public health settings.
Medical News Today recently reported on a study detailing the creation of a computational model that could predict the magnitude of flu outbreaks up to 3 weeks in advance.