October 17, 2013
Interviews Better At Predicting Mortality Than Doctors, Self-Assessments
Brett Smith for redOrbit.com – Your Universe Online
Although many of us think of regular physical exams as a way to gauge our personal health, a new study has found they are not a very reliable predictor of mortality when compared to self-assessments or even evaluations made by a trained interviewer, according to a new study in the journal Epidemiology.
"Your face and body reveal a lot about your life. We speculate that a lot of information about a person's health is reflected in their face, movements, speech and functioning, as well as in the information explicitly collected during interviews," said study author Noreen Goldman, a public affairs professor at Princeton’s Woodrow Wilson School of Public and International Affairs.
Starting in 2000, researchers associated with Social Environment and Biomarkers of Aging Study (SEBAS) have conducted home interviews, collected biological specimens and held medical examinations with middle-aged and older volunteers in Taiwan. The Princeton team used the 2006 edition of this study, which included both interviewer and physician evaluations, for their research. The study author also used death registration data through 2011 in order to determine participants’ survival status.
"Mortality is easy to measure because we have death records indicating when a person has died," Goldman said. "Overall health, on the other hand, is very complicated to measure but obviously very important for addressing health policy issues."
The researchers said they were surprised to find that physicians' ratings proved to be weak predictors of survival.
"The physicians performed a medical exam equivalent to an annual physical exam, plus an abdominal ultrasound; they have specialized knowledge regarding health conditions," Goldman explained.
"Given access to such information, we anticipated stronger, more accurate predictions of death," she said. "These results call into question previous studies' assumptions that physicians' 'objective health' ratings are superior to 'subjective' ratings provided by the survey participants themselves."
The scientists said they were also surprised to discover that interviewers' ratings were significantly more reliable for predicting mortality than self-assessments. Goldman said this was probably due to the interviewers’ consideration of their respondents' motions, appearance and awareness in addition to the thorough health data gathered during the interviews. She added interviewer ratings are possibly less affected by bias than self-reports.
"The 'self-rated health' question is religiously used by health researchers and social scientists, and, although it has been shown to predict mortality, it suffers from many biases. People use it because it's easy and simple," Goldman explained. "But the problem with self-rated health is that we have no idea what reference group the respondent is using when evaluating his or her own health. Different ethnic and racial groups respond differently as do varying socioeconomic groups. We need other simple ways to rate individual health instead of relying so heavily on self-rated health."
The Princeton researchers suggested future health studies should include interviewer ratings in surveys along with self-ratings.
"This is a straightforward and cost-free addition to a questionnaire that is likely to improve our measurement of health in any population," Goldman said.