Income inequality is linked to a greater risk of readmission to hospital, but not mortality.

The finding came from a large study of older patients in the U.S. and was published in British Medical Journal (BMJ).

Over the three year research period, about 40,000 extra hospital admissions resulted from income inequality, according to the investigators.

Scientists have known that income inequality is linked to a diversity of negative health consequences, such as:

  • reduced life expectancy
  • higher infant mortality
  • poorer self-reported health

Previous research, also in BMJ, demonstrated that there is an association between low standards of child well-being and income inequality.

However, there is little information about the potential association between income inequality and outcomes after admission to acute care hospitals.

Therefore, a team of American experts looked at the link between income inequality and probability of dying and readmission within one month after leaving hospital.

Data were gathered and examined for U.S. Medicare patients aged at least 65 years who were in hospital over a three year period (1 January 2006 and 31 December 2008). The patients’ main diagnosis was heart failure, heart attack (acute myocardial infarction), or pneumonia.

The researchers used information from the U.S. Census Bureau on income inequality at state level. The states in the three highest quarters of income inequality were analyzed in comparison with the states in the lowest quarter.

The team also looked at many other qualities of the states, patients, and hospitals that were likely to impact the results.

There were 2.6 million admissions to 4,500 hospitals included in the mortality investigation and 3.2 million admissions to 4,500 hospitals included in the readmission examination.

Results showed that income inequality was not linked to a greater chance of death within one month of admission for patients with:

  • heart failure
  • pneumonia
  • acute myocardial infarction

On the other hand, patients exposed to higher levels of inequality with any of those three conditions had an elevated risk of readmission within one month of leaving hospital.

This means, according to the scientists, that people with acute myocardial infarction and heart failure have a 1.5% increased chance of readmission and individuals with pneumonia have a 1.4% greater risk.

During the three years, the team estimated that there had been an excess of:

  • 7,153 readmissions for heart attack
  • 14,127 for pneumonia
  • 17,991 for heart failure

The results were not notably impacted by individual income and educational achievement.

Although the experts are not positive why there was no consistent association between income inequality and mortality, they suggested that, over one month, “readmission is more sensitive to social conditions than is mortality, and that an effect on mortality might have been observed had we extended the period of observation to one year.”

Additionally, they said that the report’s design might demonstrate that there were other confounding variables not accounted for in the results.

Additional research is necessary “to elucidate the mechanisms underlying these observations”, the authors concluded.

Written by Sarah Glynn