According to the International Classification of Functioning, Disability, and Health (ICF), disability is defined as disorders and limitations of activity and participation. Disability is the result of an interaction between illness and personal and environmental factors (e.g., negative attitudes, inability to use the transportation system and inadequate public facilities, and inadequate social support) (1). The Barthel activities of daily living (ADL) and the Lowton instrumental activities of daily living (IADL) indices are standardtools for measuring disability (2, 3).During recent years, the burden of disability increased by 52% worldwide. Almost 80% of these disabilities are the result of non-communicable diseases. According to the Global Burden of Disease (GBD), diabetes was the fourth leading cause of disability in the world in 2017 (4).
Disability risk factors vary across communities and regions of the world. According to a study in Australia, disability was positively associated with smoking, obesity, diabetes and being women (5). In another study in Netherlands, the most important predictors of disability in old age were previous disability and age. Other factors (such as gender, cognitive function, peer health score, obesity, hypertension, and joint pain) did not play a significant role in increasing disability (6). In another study conducted in 6 middle and low-income countries (India, Ghana, South Africa, Mexico, Russia, and China), age, chronic diseases (such as hypertension, angina, stroke, diabetes, chronic lung disease, asthma, and arthritis) and depression were identified as the most important factors affecting disability. Other factors (such as gender, marital status, education, social capital, physical activity, BMI) either had no role or played a different role in societies (7).
In a study of the elderly in Spain, the hazard ratios (HRs) in the physical disability domain questionnaire were 1.14 to 1.52 for total mortality and 1.29 to 1.58 for cardiovascular diseases (CVD) compared to people with no disabilities. The researchers found that in the elderly with disabilities, physical activity reduces the risk of total death as well as death from CVD. The death rate in disabled people is similar to inactive people with no disability. The suggested mechanism is physical activity reduces obesity, sarcopenia, falls and more. Physical activity also improves one's social network, mood, and depression; all of them are associated with reduced morbidity and mortality (8).
Dhamoon et al. showed that although the maximum rate of disability due to stroke and myocardial infarction (MI) occurs during the stroke, the rate of disability continues to increase annually in people who experience these vascular events. This is even worse in people who have had a stroke. (9). Therefore, if the disability status is determined using self-report, it may consider the timing of the underlying disease.
Iranian population has quadrupled over the last six decades, while population growth has almost halved (10). Also, from 1970 to 2010, life expectancy increased from 50.6 to 71.6 years for Iranian men and from 56.2 to 77.8 yearsfor women. Iran is one of the countries that during this period has experienced significant improvements in life expectancy at birth in both sexes (11). One of the most common problems in Iranian public health is the high prevalence of cardio-metabolic risk factors. For example, the results of a meta-analysis showed that about one-third of Iranians had metabolic syndrome. Besides, the prevalence of this syndrome increases with age (12). According to Sadeghi et al., only due to aging, the CVD burden and DALY in the Iranian population will double in 2025 compared to 2005 (13). The highest YLL, YLD, and DALY will be in people over 80 years of age (14). The purpose of this study was to investigate the relationship between cardio-metabolic and demographic risk factors and disability using basic and instrumental activities of daily living, in people 60 years and older in Iran.