Academic journal article Bulletin of the World Health Organization

Current and Future Worldwide Prevalence of Dependency, Its Relationship to Total Population, and Dependency Ratios

Academic journal article Bulletin of the World Health Organization

Current and Future Worldwide Prevalence of Dependency, Its Relationship to Total Population, and Dependency Ratios

Article excerpt

Introduction

There were major changes in population structures and disease patterns in the last century in economically more developed countries (the so-called demographic and epidemiological transitions). Other countries are currently experiencing these transitions, or will do so in the coming decades.

The "demographic transition" describes the shift from high fertility and high mortality, to low fertility and low mortality. This results in increasing life expectancy and an increasing proportion of elderly people in the population. The "epidemiological transition" describes the change from a predominance of infectious diseases, with high maternal and child mortality, to a predominance of chronic diseases.

An important effect of chronic diseases is a limitation in functional abilities, or "disability" (1). The inability to perform some key activities (e.g. basic mobility, feeding, personal hygiene and safety awareness) leads to "dependency"--the need for human help (or care) beyond that customarily required by a healthy adult. Most such help is given by family members or other "informal" carers (2). "High-intensity caring" is associated with restricted social and economic opportunities, and detrimental effects on the mental and physical health of the carer (3-5).

This study was conducted using data from the Global Burden of Disease Study (6), and United Nations population projections (7), to estimate the number of people who needed daily care, and to make predictions up to 2050.

Methods

Global burden of disease study

The age-specific and sex-specific prevalances of 483 diagnoses were estimated for the year 1990 using the best available data, or expert opinion if data were lacking, for eight country groups defined by the World Bank as being demographically and economically similar (8, 9). The groups were established market economies, former Socialist economies of Europe, sub-Saharan Africa, Latin America and Caribbean, Middle-Eastern crescent, China, India and Other Asia and Islands. Severity scores for disability were established empirically (as disability preference weights) for 22 sample diagnoses (or "indicator conditions"). These diagnoses were described in terms of the impairments typically associated with them. Severity scores were determined by an international panel of health professionals. An iterative "person trade-off" approach was used--participants chose whether it was more desirable to treat a given number of people with one condition than to treat a given number with another condition. After each round of scoring for each condition, the policy consequences of the ratings were fed back, to inform changes in scores made for the next round. Scores for the remainder of the 483 diagnoses were estimated by comparison with these 22 sample diagnoses, also by an expert panel (10). Diagnoses were then divided into seven classes of disability according to their scores. The prevalence of each disability class was calculated by summing the prevalences of diagnoses within that class (9). The types of condition included in each disability class are shown in Table 1.

Estimating dependency

It was assumed that there would be an approximate relationship between the class of disability and the need for care. For each disability class, the sample conditions used in the weighting process were considered, and a judgement made as to the frequency of care required. The judgements were generally uncontentious, but to verify them, a group of 20 health professionals was surveyed. The health professionals included nurses, doctors and physiotherapists from around the world, working in a British National Health Service hospital. The countries represented included Australia, Chile, Germany, Ghana, Jamaica, Myanmar, Nigeria, Norway, the Philippines, Sri Lanka, Ukraine and the United Kingdom. For each of the 22 conditions described, participants were asked to decide how often an adult patient would require human help with his or her personal, domestic or health needs, beyond that which would be expected for a healthy adult. …

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