Large-scale epidemiological study and MHLW data analysis reveals residents of rented flats at higher risk of cardiovascular disease

Elderly people living in rented flats have a higher risk of developing and dying from cardiovascular diseases compared with those living in detached houses or in flats owned by themselves or their families. Assistant Professor Wataru Umishio in the Department of Architecture and Building Engineering, School of Environment and Society, Assistant Professor Sakura Kiuchi in the Department of Dental Public Health, Graduate School of Medical and Dental Sciences, and Professor Jun Aida at the Center for Well-being Research Advancement, Institute of Future Science at the Institute of Science Tokyo, together with Professor Toshiyuki Ojima at Hamamatsu University School of Medicine; Professor Masashige Saito at Nihon Fukushi University; and Associate Professor Masamichi Hanazato at Chiba University, revealed this through an analysis combining data from JAGES (Japan Gerontological Evaluation Study), a large-scale epidemiological study aimed at healthy longevity, with cause-of-death data from the Ministry of Health, Labour and Welfare (MHLW). The findings were published in BMJ Public Health.

The WHO Housing and Health Guidelines issued in 2018 indicate that maintaining indoor winter temperatures above 18℃ and installing insulation in housing can improve cardiovascular (brain and heart) health. However, previous research on housing and cardiovascular health has mainly used indicators that fluctuate in the short term, such as blood pressure. Few studies have examined the impact of housing on the development and mortality of cardiovascular diseases.

The research group used data from a six-year follow-up study conducted from January 1, 2012 to December 31, 2017, targeting 38,731 elderly people aged 65 and older. By combining questionnaires on housing types ("owned detached houses," "owned flats," "rented detached houses," and "rented flats"), date-of-death data held by municipalities, and cause-of-death data held by the MHLW, they compared cumulative mortality rates from cardiovascular diseases by housing type. The results showed that cumulative mortality rates were highest in the order of rented flats, owned detached houses, and owned flats, and testing of differences in Kaplan-Meier curves revealed statistically significant differences (rented detached houses were excluded due to the small sample size).

Subsequently, using a competing risk model and adjusting for individual attributes such as age and sex, socioeconomic factors such as income and education, and lifestyle habits such as diet and exercise, sub distribution hazard ratios were calculated. Analysis results showed that the hazard ratio for rented flats compared with owned flats was 1.78 overall and 2.32 for men, both significant (for women it was 1.29, not significant). In other words, the six-year risk of cardiovascular death in rented flats is interpreted as 78% higher overall and 132% higher for men compared with owned flats.

This study revealed that housing type affects cardiovascular mortality, with particularly high mortality risk in rented housing. The high mortality risk in rented housing is thought to be partly due to the generally lower housing performance (insulation performance, etc.) in rentals compared with owner-occupied homes. Since rental housing owners do not live in the properties themselves, they tend not to invest in improving housing performance, resulting in lower housing performance compared with owner-occupied homes (split incentive).

The United Kingdom uses the Housing Health and Safety Rating System (HHSRS). When housing is judged to have health and safety deficiencies, orders for housing renovation or demolition are issued to property owners, including for rental housing. In Japan, a new energy efficiency labeling system for buildings began in April 2024, making the display of energy efficiency labels, including insulation performance, a mandatory effort for rental housing as well. This is a first step.

Going forward, conducting large-scale environmental measurements of housing and combining them with health data is expected to lead to the establishment of objective housing environment standards that achieve disease prevention and healthy longevity.

Journal Information
Publication: BMJ Public Health
Title: Combination of housing type (detached houses vs flats) and tenure (owned vs rented) in relation to cardiovascular mortality: findings from a 6-year cohort study in Japan
DOI: 10.1136/bmjph-2025-003073