In an international context, Norway stands as an egalitarian country with only small class and income disparities, in which everyone basically has equal access to universal health care. Yet research on self-reported health and mortality data has shown that Norway has social inequalities on par with many other countries in Western Europe.

Self-reported are often used in population studies where health is being mapped. Participants in the survey are asked to rate how they perceive their own health right now, often using the answer choices "very good," "good," "fair" or "bad."

Now, through a comparison of self-reported health and mortality, researchers at the Norwegian University of Science and Technology (NTNU) have examined whether these answers are reliable. Would having a better understanding of their own health mean that more advantaged populations assess their health more accurately than less advantaged ones? One of the findings from the survey surprised the scientists.

Higher mortality among the unemployed

The lower on the socioeconomic ladder one finds oneself, the more frequently most health problems occur. Socioeconomic status refers to education, occupation or income. Looking at Norway's 1980 census results, for example, a male chef had a life expectancy of 71 years, while a lecturer had a life expectancy of 81 years.

What happens when the chef and the lecturer are asked how their health is right now? Are the criteria that are applied the same?

NTNU researchers wanted to examine whether self-reported health reflects reality across different socioeconomic groups. It was assumed that people from higher socioeconomic groups have skills that make them better able to understand how chronic disease and other conditions can affect health and mortality. It was also asserted that people with low social status would complain more about their health, and that the social being measured were not real.

However, the study results show that the relationship between self-reported health and mortality is about equally strong across occupational classes and across income groups. This increases the credibility of population studies that use self-reported health measures.

Nevertheless, the study uncovered something that surprised the group that conducted the study: Unemployed people with self-reported poor health stood out. They had three times higher mortality than expected, compared to individuals in the highest socioeconomic class. For unemployed women, the mortality rate was two times higher.

Social health disparities exist

So it is not true that the unemployed "complain" more about their health than those who are better off. Rather, it appears that they are reporting that their health is better than it actually is.

"Our research shows that social health inequalities are a reality and that they represent a national challenge. We can conclude that studies comparing self-reported health between unemployed and working populations probably underestimate the actual health differences, and these disparities are therefore greater than anticipated," says sociologist Christoffer Holseter.

According to Professor Steinar Krokstad, head of NTNU's HUNT Research Centre, in health are also reflected in absenteeism. The study shows that these differences are largely due to real differences in health and that we should take people's self-reported health seriously.

"There is a bias that the lower down on the social ladder you are, the more you complain. Our findings upend this idea," adds Sociology Professor Terje Andreas Eikemo.

Eikemo is one of 17 researchers in NTNU's Outstanding Academic Fellow Program and manages two of the EU's major health surveys.

"When someone says that their health is bad, we should listen. Given that the study has revealed even greater differences between the unemployed and employed than anticipated, we should also increase measures to even out the socioeconomic health inequalities," he says.

Extensive database

In the study, researchers used data from the Health Survey in Nord-Trøndelag (HUNT) that was conducted from 1984-1986, where almost 90 per cent of the entire adult population over 20 years old participated. HUNT is one of the largest databases of health information on the Norwegian population.

NTNU researchers chose to include data from all adults aged 25 years and over, with the aim that the participants would have been well established socioeconomically. After excluding pensioners and those who had not answered all the questions, the researchers were left with a sample of just over 42,000 participants.

The data were then compared with Statistics Norway's death register, before researchers analysed the relationship between self-reported health and mortality in different occupational classes and income groups. The analysis was adjusted for age, chronic illness, disability and lifestyle factors to account for health variations in the population.

HUNT gives a good picture

The analysis showed that 73 per cent of participants rated their health as very good or good. During the period following, 12.3 per cent of the female sample and 17.3 per cent of the male sample died.

The analysis shows a clear correlation between self-reported health and mortality. 12.4 per cent of those who said they had good health, died in the follow-up period, as compared to 26 per cent of those who said they had poor health.

Men without recorded income showed higher mortality, both among those who reported good health and bad .

"Data from HUNT do a good job representing the country as a whole. We know that trends in cause-specific and disability retirement follow national trends closely," says Holseter.

"A strength of this study is that 90 per cent of the population was followed over a long time. It puts HUNT in a unique position," adds Krokstad.

More information: "Self-rated health and mortality in different occupational classes and income groups in Nord-Trøndelag County, Norway." Tidsskr Nor Laegeforen. 2015 Mar 10;135(5):434-8. DOI: 10.4045/tidsskr.13.0788