Associations between natural area availability and morbidity: a cross-sectional study using health insurance billing data from Germany
- 1Zentralinstitut für die kassenärztliche Versorgung in der Bundesrepublik Deutschland, Berlin, Germany
- 2Institute of Medical Sociology and Rehabilitation Science, Charite - Universitatsmedizin Berlin, Berlin, Germany
- 3Einstein Center Population Diversity, Berlin, Germany
Abstract
Objectives: Access to nature has been associated with improved physical and mental health through multiple pathways, including stress reduction, physical activity promotion and reduced chronic disease risks. In contrast, urban areas lacking nature often expose residents to pollution, noise and heat. This study examines whether natural area availability is associated with morbidity.
Design: We conducted a cross-sectional study using 2023 outpatient billing data, with the Charlson Comorbidity Index (CCI) as a measure of morbidity. (Mixed) linear regression models were applied in ecological-regional (full sample) and individual (2.5% stratified random sample) designs to examine associations between CCI and three natural area indicators (semi-natural, forest and water) while controlling for sociodemographic, socioeconomic and infrastructural variables.
Setting: Nationwide ambulatory claims data (secondary data analysis).
Participants: Data from 72.7 million individuals with statutory health insurance in Germany were used.
Results: In the ecological-regional analysis, higher proportions of semi-natural, forest and water areas per inhabitant were negatively associated with the average regional CCI, with coefficients of −0.433 (95% CI −0.723 to −0.143, p=0.004), −0.080 (95% CI −0.139 to −0.021, p=0.008) and −0.612 (95% CI −1.137 to −0.087, p=0.022). Multilevel analyses confirmed these associations at the individual level: an increase of one SD of semi-natural (−0.013, 95% CI −0.023 to −0.003, p=0.009), forest (−0.012, 95% CI −0.022 to −0.002, p=0.024) or water area (−0.011, 95% CI −0.021 to −0.001, p=0.032) was each associated with a lower CCI.
Conclusion: Regions with more natural areas were associated with lower morbidity. Green spaces may support better health. Equitable access to natural environments could promote population health.
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BibTeX
@article{muller2026associations,
title = {{Associations between natural area availability and morbidity: a cross-sectional study using health insurance billing data from Germany}},
author = {Doreen Müller and Zehra Durmus and Manas K Akmatov and Claudia Kohring and Jakob Holstiege and Johannes Hagelskamp and Julie Lorraine O’Sullivan},
journal = {BMJ Open},
year = {2026},
month = sep,
doi = {10.1136/bmjopen-2026-119383},
url = {https://bmjopen.bmj.com/lookup/doi/10.1136/bmjopen-2026-119383},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Associations between natural area availability and morbidity: a cross-sectional study using health insurance billing data from Germany
AU - Doreen Müller
AU - Zehra Durmus
AU - Manas K Akmatov
AU - Claudia Kohring
AU - Jakob Holstiege
AU - Johannes Hagelskamp
AU - Julie Lorraine O’Sullivan
PY - 2026
DA - 2026/09/30
JO - BMJ Open
DO - 10.1136/bmjopen-2026-119383
UR - https://bmjopen.bmj.com/lookup/doi/10.1136/bmjopen-2026-119383
AB - Objectives: Access to nature has been associated with improved physical and mental health through multiple pathways, including stress reduction, physical activity promotion and reduced chronic disease risks. In contrast, urban areas lacking nature often expose residents to pollution, noise and heat. This study examines whether natural area availability is associated with morbidity. Design: We conducted a cross-sectional study using 2023 outpatient billing data, with the Charlson Comorbidity Index (CCI) as a measure of morbidity. (Mixed) linear regression models were applied in ecological-regional (full sample) and individual (2.5% stratified random sample) designs to examine associations between CCI and three natural area indicators (semi-natural, forest and water) while controlling for sociodemographic, socioeconomic and infrastructural variables. Setting: Nationwide ambulatory claims data (secondary data analysis). Participants: Data from 72.7 million individuals with statutory health insurance in Germany were used. Results: In the ecological-regional analysis, higher proportions of semi-natural, forest and water areas per inhabitant were negatively associated with the average regional CCI, with coefficients of −0.433 (95% CI −0.723 to −0.143, p=0.004), −0.080 (95% CI −0.139 to −0.021, p=0.008) and −0.612 (95% CI −1.137 to −0.087, p=0.022). Multilevel analyses confirmed these associations at the individual level: an increase of one SD of semi-natural (−0.013, 95% CI −0.023 to −0.003, p=0.009), forest (−0.012, 95% CI −0.022 to −0.002, p=0.024) or water area (−0.011, 95% CI −0.021 to −0.001, p=0.032) was each associated with a lower CCI. Conclusion: Regions with more natural areas were associated with lower morbidity. Green spaces may support better health. Equitable access to natural environments could promote population health.
SN - 2044-6055
SN - 2044-6055
ER -