Discussion
Educational inequality in pneumonia mortality in Colombia is on the rise. Age-standardised mortality rates by pneumonia in Colombia (1998–2015) were found to be larger among men than in women; much larger in senior compared with younger ages; and consistently higher among those less educated. We found relatively stable trends of mortality by pneumonia in both sexes with a strong rise during the last years due to an alarming increase in mortality among senior men and women from 2012/2013, respectively. By educational level, the final peak from 2013 was found only among those with tertiary education, but not significant. We found significant increases in pneumonia mortality rates among those with primary education, along the whole period. However, those with tertiary education strong and steadily decreased mortality up to 2013. Consequently, a significant steady increase in the RII during all period was found among men and women.
Pneumonia mortality rates in Colombia evidenced a clear age-dependency, with lowest rates for young adults and much higher rates for senior adults. In less than two decades, mortality due to pneumonia among 25+ years showed a worrying increase for women and men. Our results are consistent with the Global Burden of Disease study, where deaths occurred in adults with 50–69 years and in older than 70 due to lower respiratory infections increased 26.5% (95% CI 23.2 to 29.7) and 33.6% (95% CI 31.2 to 36.1) from 2007 to 2017, respectively. Additionally, among adults older than 70 years, deaths increased from pneumococcal pneumonia (60.4% (95% CI 39.7 to 79.9)), influenza (91.1% (95% CI 82.3 to 99.6)) and respiratory syncytial virus pneumonia (100.3% (95% CI 92.4 to 108.6)) between 1990 and 2017.54 A positive evolution that took place in this timeframe is the decrement of mortality rates among young adults, however this was not a substantial one.
In our analysis, differences between the lowest and highest educated are reflected in the RRs estimates finding much higher risk of dying from pneumonia in adults with low education level. Our results are consistent with the findings reported by Huisman et al in a mortality inequalities analysis conducted in eight western European populations. They calculated a RR of 1.45 (95% CI 1.37 to 1.54) between the pneumonia mortality rate in low-educational groups ≥45 years as a proportion of mortality rate in high educational groups.55 Therefore, they found that RRs among pneumonia mortality rates were diminishing as age increases, as we found in our analyses.55
ASMR were higher in lower educated, showing how low education could be a good proxy for conditions of vulnerability,56 in which the risk of death from pneumonia is increased. This evidence is very important for policymakers in avoidable mortality. Our results could be linked with previous analyses that show how low educational level is associated with mortality, likely contributing to lower access to healthcare as well as diminished awareness and adoption of policy measures planned by public health stakeholders, which increases risk of poor clinical outcomes and mortality.57–59
Other authors have used similar tools to study educational differences in mortality due to chronic diseases, for example, Manor et al, in Israel, studied educational differentials in mortality from cardiovascular disease among men and women.59 In other study, Mackenbach et al studied inequalities in lung cancer mortality by the educational level in 10 European populations during the 1990s.58 Similarly, Stirbu et al compared the magnitude and the contribution of educational inequalities in mortality avoidable by medical care in 16 European countries.60 And, in Colombia de Vires et al, have studied inequalities in cervical cancer mortality by educational level in Colombia.40 41
Given that the impact of inequalities in educational level on mortality is evident, the explanations of this probable association could be related to how healthcare providers, both preventive and curative, deliver information to patients without considering the diverse cultural contexts as educational differentials. According to pneumonia deaths, having high levels of education would allow us a better understanding about preventive measures such as vaccination. In 1997, the Advisory Committee on Immunisation Practices updated the recommendations to vaccinate the entire population over ≥65 years.61 In Colombia, immunisation in those aged ≥60 years against pneumococcus is included at the expanded immunisation programme. Similarly, we can have more knowledge about signs and symptoms of alarm, and therefore, seek timely attention. And, after receiving care, you can be more adherent to the treatments and recommendations of health professionals.
Immunisation in older adults has been promoted during the last decade in Colombia. However, the reported vaccination rates remain low. For example, Cano et al in 2012 conducted a cross-sectional survey in a sample of 2000 population in a survey in Bogota. The results reported coverage for vaccination among individuals of 60 years and older is 73.0% for influenza, 57.8% for pneumococcus and 47.6% for tetanus.62 However, these coverages are surely lesser in other Colombian territories. There is enough evidence regarding the association between educational status and vaccination. A Colombian study found that a mother completing high school or above was associated with a 16% higher odds of being immunised.63 Then, vaccination campaigns in older adults should be strengthened to increase vaccination coverage, especially in groups more vulnerable, in order to reduce mortality rates due to pneumonia.
Despite several strengths, our work has some limitations that should be considered. First, data on mortality were obtained from mortality registries of DANE vital statistics, while data on the population distribution by education were obtained from censuses and demographic projections. The latest may have led to the so-called numerator/denominator bias, which usually results in an overestimation of disparities.43 Furthermore, for some years, data on population size were obtained from demographic projections combined with distributions of education from surveys. To assess the impact of this potential bias, we experimented with different education distributions from multiple data sources, showing that the overall trends in our study were robust to different assumptions on the distribution of education.40 64 Additionally, despite the joinpoint regression did not identify this oscillation, a peak for pneumonia is visible in 2005–2006 for senior men and women. To the best of our knowledge, no previous evidence exists explaining that peak, and further retrospective research must be necessary to be addressed that change in morbidity and/or lethality of pneumonia during that period. A better knowledge of this fluctuation will potentially contribute to understand strong oscillations of infectious diseases and the vulnerability of the senior population to better address epidemics of endemic severe respiratory infections.
The rise in education levels during the last decades has contributed to improve population well-being, longevity and health.65 However, these improvements have been achieved unequally, especially in LMIC. In conclusion, a significant increase on the educational inequalities in mortality due to pneumonia during all period was found among men and women. This shows deficiencies in educational policy in terms of equity. Efforts to reduce pneumonia mortality in adults improving population health by raising education levels should be strengthened with policies that assure widespread access to economic and social opportunities. Reducing exposure to pneumonia risk factors in low-educational populations should be developed and implemented through efficient interventions like vaccination in elders. Further research is needed to enhance the understanding of inequalities in infectious disease mortality, including older populations and other pathologies.