Inequalities in non communicable diseases

1. Key messages

In 2018, as observed previously, socio-economic inequalities were present for being affected by a non-communicable disease. The percentage of people reporting a chronic illness or condition was highest among people of the lowest socioeconomic level, and this percentage decreased as the socio-economic position increases. For this general indicator “reporting a chronic disease’”, the socio-economic inequalities were low (after adjustment for age).
 
However, the inequalities in suffering from multiple conditions together (multimorbidity) were larger, meaning that people of the lower SE are more prone to cumulate health problems. 
 
In 2018 inequalities were also observed in many specific chronic conditions, namely for osteoarthritis, high blood pressure, urinary incontinence in people aged 65+, migraine-like headache, chronic obstructive pulmonary disease (COPD) in people aged 65+, diabetes, asthma and acute myocardial infarction (AMI) in 65+.
 
Over time, the inequalities in reporting a chronic condition or multimorbidity have fluctuated. They have decreased in 2018 as compared to 2013.  
 
For most of the specific conditions also, inequalities did not increase or even tended to slightly decrease between 2013 and  2018. For diabetes and COPD the inequalities tend to have slightly decreased already since 2008; for asthma a decrease was observed since 2013. 

2. Background

Socio-economic (SE) health inequalities refer to systematic disparities in health between SE groups, most often in disfavour of those on the lower position of the social and/or economic scale. SE health inequalities have been consistently observed in industrialized societies for the whole scope of health-related indicators, ranging from health determinants to mortality [1;2]. Tackling health inequalities is a priority for the WHO [3], the European Union [4], and for Belgium [5-7]. In order to assess progress towards reducing health inequalities, it is important to measure and monitor them [8,9].
 
Inequalities in non-communicable diseases (NCDs) have been computed from the data of the Belgian Health Interview Surveys 1997-2018. The educational level (EL) (in three categories: low, mid, high) was chosen as a marker of the socio-economic position to examine inequalities. Methodological details can be found in this annexe. Beside the prevalence of NCDs by socio-economic level, we also calculated the magnitude of the inequalities by computing three inequality indices: 
  • The absolute difference, which is the difference between the age-adjusted prevalence rates in the low versus the high ELs,
  • The relative difference (Rate Ratio), which is the ratio of the age-adjusted prevalence rates in the low versus the high ELs,
  • The Population Attributable Fraction (PAF), i.e. the percentage of gain in health expected in the whole population if all groups experienced the health of the most educated group.

3. Results

Situation in 2018

SE inequalities for the global indicator “suffering from a chronic condition” are small: after age-adjustment, chronic conditions are reported by 31% of people of the low EL versus 27% of people in the high EL, leading to a rate difference of 3.9 percentage-point (ppt) and a rate ratio of 1.1.  However, the inequalities are larger if the co-occurrence of several chronic conditions (multimorbidity) is considered, with a rate difference reaching 5.7 ppt and a rate ratio of 1.4 (meaning a 40% excess of multimorbidity in people from the lowest versus people of the highest EL).
 
When looking at each condition separately, we observe SE inequalities in many conditions. This is the case for osteoarthritis, high blood pressure (in people aged 65+), migraine-like headache, chronic obstructive pulmonary disease (COPD) in people aged 65+, urinary incontinency in people aged 65+, diabetes, asthma, acute myocardial infarction (AMI) in 65+.
 
The absolute inequalities (rate differences) were moderate, ranging from 1.4 ppt for AMI (in 65+) to 6.6 ppt for urinary incontinence (in 65+).
 
The relative inequalities were:
  • large for AMI (in 65+) and COPD (in 65+), with respectively 2.0 and 1.9 times more people suffering from AMI (65+) and COPD (65+) in the low than the high EL group;
  • moderate (between 1.4 and 1.6) for urinary incontinence (65+), migraine-like headache, diabetes, and asthma;
  • small (between 1.1 and 1.3) for osteoarthritis, and high blood pressure. 
 If all EL groups had the same level as the high EL group then the prevalence of AMI (65+), COPD (65+), urinary incontinence (65+), and diabetes would be respectively reduced by 37.8%, 28.6%, 21.5%, and 20.3% in the whole population. 
 

Socio-economic inequalities in selected non-communicable diseases, people aged 15 years and over, Health Interview Survey, Belgium, 2018
Source: Own calculation based on Health Interview Survey [10]
* statistically different from 0% for absolute difference and PAF, and statistically different from 1 for the relative difference (p<0.05)

Age-adjusted prevalence rate low EL Age-adjusted prevalence rate high EL Absolute difference Relative difference PAF
Chronic conditions in general  
% reporting chronic disease 31.2% 27.3% 3.9%* 1.1* 5.1%
% reporting multimorbidity 19.1% 13.3% 5.7%* 1.4* 12.7%*
Specific conditions  
% reporting osteoarthritis 21.5% 17.5% 4.0%* 1.2* 6.7%
% reporting high blood pressure 19.1% 16.8% 2.4%* 1.1* 5.2%
% reporting urinary incontinence among people aged 65+ 17.5% 10.9% 6.6%* 1.6* 21.5%*
% reporting migraine-like headache 12.1% 8.8% 3.3%* 1.4* 13.3%*
% reporting COPD among people aged 65+ 11.1% 5.8% 5.4%* 1.9* 28.6%*
% reporting diabetes 7.5% 4.7% 2.9%* 1.6* 20.3%*
% reporting asthma 7.2% 4.8% 2.4%* 1.5* 16.8%*
% reporting myocardial heart infarction among people aged 65+ 2.8% 1.4% 1.4% 2.0 37.8%

Trends

The percentage of people reporting one or more chronic diseases (multimorbidity) has increased since their first estimate in the HIS (2001), even after age-adjustment. The prevalence of many specific diseases has also increased (however, it decreased for COPD). The evolution of these percentages differs by SE level and by pathology, leading to changes in the SE inequalities by NCDs.
 
For reporting a chronic condition,  the inequalities (as measured with all three inequality indices)  strongly increased from 2001 to 2013, reaching in 2013 a large level of absolute inequality (10 ppt). In the last period (2013 to 2018), the inequalities in reporting a chronic condition, as measured with all three inequality indices, dropped.
 
For multimorbidity, a decrease of inequality was observed in 2013 and further in 2018 as compared to  2004 with all three inequality indices. 
 
When looking at the evolution of the prevalence and inequalities by specific condition, we observe that:
  • Inequalities indicators for urinary incontinence (65+), IMA (65+), high blood pressure and osteoarthritis have no notable trends.
  • The age-adjusted prevalence of migraine-like headache was stable between 2004-2013 and increased in 2018. The rate difference significantly decreased between 2001 and 2008, but then increased in 2013 and 2018 (increase not significant), with a same evolution observed for the relative inequalities (statistically not significant). So an increase (not significant) in inequalities is observed in migraine-like headache in the last period.
  • The age-adjusted prevalence of COPD (65+) decreased from 2001 to 2018, with variable evolutions by EL. The inequalities in COPD prevalence (measured both with rate difference and rate ratio) decreased between 2008 and 2018.
  • The age-adjusted prevalence of diabetes has increased in all EL groups since 1997, with a small stagnation in 2008. Qua inequalities, the low-versus-high absolute difference in rates remained stable since 2008 at a high level; the relative difference has decreased since 2008, reflecting a smaller proportional increase of the prevalence of diabetes in the low than in high EL. So, even if the RR has decreased in 2018, the global evolution of inequality for diabetes is still disappointing: indeed, it is important to obtain a reduction in absolute inequalities, which would require a more favorable evolution of the prevalence of diabetes in the socially disadvantaged group than in the advantaged group.
  • The age-adjusted prevalence of asthma was stable until 2013 and increased in 2018. The inequalities in asthma have increased from 2001 to 2013 (measured as rate difference and rate ratio) and decreased in 2018.
When looking at inequalities at population level, the Population Attributable Fraction (PAF) was particularly high for COPD (65+) and diabetes in 2008 and has decreased afterwards. For all indicators, the PAF tends to decrease since 2008 or since 2013, which is partly due to a decrease of the rate ratio, and to a change in the population composition, with the low educated group representing a decreasing share of the population over time. 

 

  • Chronic condition
  • Multimorbidity
  • Migraine
  • COPD
  • Diabetes
  • Ashtma

Prevalence of chronic condition by educational level, 1997-2018, Belgium
Source: Own calculation based on Health Interview Survey, Sciensano [10]

Prevalence of multimorbidity by educational level, 1997-2018, Belgium
Source: Own calculation based on Health Interview Survey, Sciensano [10]

Prevalence of migraine-like headache by educational level, 1997-2018, Belgium
Source: Own calculation based on Health Interview Survey, Sciensano [10]

Prevalence of COPD (65+) by educational level, 1997-2018, Belgium
Source: Own calculation based on Health Interview Survey, Sciensano [10]

Prevalence of diabetes by educational level, 1997-2018, Belgium
Source: Own calculation based on Health Interview Survey, Sciensano [10]

Prevalence of asthma by educational level, 1997-2018, Belgium
Source: Own calculation based on Health Interview Survey, Sciensano [10]

 

 

  • Absolute difference
  • Relative difference
  • PAF

Absolute difference in NCDs indicators, Belgium, 1997-2018
Source: Own calculation based on Health Interview Survey, Sciensano [10]

Relative difference in NCDs indicators, Belgium, 1997-2018
Source: Own calculation based on Health Interview Survey, Sciensano [10]

PAF in NCDs indicators, Belgium, 1997-2018
Source: Own calculation based on Health Interview Survey, Sciensano [10]

4. Read more

View the metadata for this indicator

HISIA: Interactive Analysis of the Belgian Health Interview Survey

Definitions

Percentage-point
The Percentage-point (ppt) is the arithmetic difference between two percentages, for instance with 16% in group A and 8% in group B, the difference is 8 ppt, corresponding to a relative excess of 100%.
Multimorbidity
The occurrence of at least 2 of the following diseases: chronic lung disease, heart disease, hypertension, diabetes, cancer, and arthropathy.

References

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  7. Arrêté royal du 18 juillet 2013 portant fixation de la vision stratégique fédérale à long terme de développement durable: http://www.etaamb.be/fr/arrete-royal-du-18-juillet-2013_n2013011468.html. Moniteur Belge. 2013 Oct 8;
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  10. Health Interview Survey, Sciensano, 1997-2018. https://www.sciensano.be/en/projects/health-interview-survey