Is Population Density Associated with Non-Communicable Disease in Western Developed Countries? A Systematic Review.

Area of Science:

• Environmental Epidemiology
• Public Health Research
• Non-Communicable Disease (NCD) Etiology

Background:

• Extensive research over three decades has explored the relationship between population density and health outcomes.
• A systematic synthesis of this evidence, particularly concerning non-communicable diseases (NCDs), has been lacking.
• Understanding these associations is crucial given rising global morbidity and mortality rates.

Purpose of the Study:

• To systematically review and synthesize quantitative evidence on the association between population density and NCDs.
• To evaluate the quality of existing ecological studies on this topic.
• To identify potential risk markers and underlying mechanisms linking population density to NCDs.

Main Methods:

• Systematic literature review adhering to Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines.
• Inclusion of quantitative studies published since 1990 focusing on population density and NCDs in Westernized countries.
• Utilized a quality assessment tool specifically designed for ecological studies to evaluate 54 included studies.

Main Results:

• High population density is associated with increased mortality from cancers, cardiovascular disease, and Chronic Obstructive Pulmonary Disease (COPD).
• High population density also correlates with a higher incidence of certain cancers, asthma, and club foot.
• Conversely, diabetes incidence showed an association with low population density, highlighting complex relationships.

Conclusions:

• Both high and low population density serve as risk markers for various NCDs, suggesting unidentified etiological factors.
• Complex interactions exist between population density, the built environment, greenspace, and man-made exposures.
• Further research is imperative to elucidate causative agents and establish definitive links for each NCD.