Social inequalities are created before the onset of the illness, rather than after it, according to researchers.
Socioeconomic status has an impact on multimorbidity, a study published in The Lancet Public Health found, but does not affect the risk of death after multiple chronic diseases develop, including heart disease, diabetes, and others.
Social inequalities are created before the onset of the illness, rather than after it, according to researchers. This means that social inequality is the cause, not the result of or a factor in the prognosis of the illness.
The study was based on data collected from the Whitehall II cohort study, which is currently ongoing. The study collected data on British civil servants between the ages of 35-55. Of the 10,308 individuals in the study, 6465 had relevant data, which were collected between 1985 to 1988. Electronic health records were used to assess the incidence of multimorbidity (2 or more of diabetes, coronary heart disease, stroke, chronic obstructive pulmonary disease, depression, arthritis, cancer, dementia, and Parkinson disease) and mortality.
Indicators of education, occupational position, and literacy were taken for each participant. Between 2002 to 2016, participants underwent 4 assessments for frailty and disability. Frailty was defined as 2 or more of low physical activity, slow walking speed, poor grip strength, weight loss, and exhaustion; disability was defined as 2 or more difficulties in bathing, dressing, going to the toilet, transferring, feeding, and walking.
Researchers used multistate models to examine social inequalities in transitions from healthy to unhealthy, and subsequently to mortality.
Participants were followed up for a median of 23.6 years; the followup period ended in 2017.
Of the 6425 participants:
Multimorbidity (hazard ratio [HR] 4.12; 95% CI, 3.41—4.98), frailty (HR 2.38; 95% CI, 1.93–2.93), and disability (HR 1.73; 95% CI, 1.34–2.22) were associated with increased risk of mortality; these associations were not modified by socioeconomic status.
Most deaths (73.7%) were due to cardiovascular disease or cancer.
In multistate models, occupation was the socioeconomic status indicator that was most strongly associated with inequalities in the transition from healthy state to multimorbidity (HR 1.54; 95% CI, 1.37—1.73), to frailty (HR 2.08; 95% CI, 1.85–2.33]), and to disability (HR 1.44; 95% CI, 1.18–1.74).
Socioeconomic status indicators, although associated to the onset of the disease, did not affect transitions to mortality in those with multimorbidity, frailty, or disability. Occupation, which reflects education, salary, and social status, was found to be strongly associated with adverse health conditions.
The most frequent component in multimorbidity was coronary heart disease; in frailty it was physical inactivity; and in disability it was difficulty with dressing.
“Primary prevention is key to reducing social inequalities in mortality. Of the three adverse health conditions, multi-morbidity had the strongest association with mortality, making it a central target for improving population health,” researchers wrote.
Researches found that traditional disease progression were not seen in this study, meaning risk factors leading to disease or condition, then suubsequent loss of function, disability, and death. The authors said this was due to the fact that the median age at onset of multimorbidity, frailty, and disease was similar.
“Our analysis of the transitions from adverse health conditions to mortality show that multi-morbidity is an important target to improve population health and reduce social inequalities in mortality,” they wrote. “Health care systems that are organized around single-system illness will need to be restructured to reflect the multi-organ dysfunction experienced by older adults.”
Dugravot A, Fayosse A, Dumurgier J, et al. Social inequalities in multimorbidity, frailty, disability, and transitions to mortality: a 24-year follow-up of the Whitehall II cohort study [published online December 11, 2019]. Lancet Public Health. doi: 10.1016/S2468-2667(19)30226-9.