Zulfiqar Ali, Ph.D (Assistant Professor of
Statistics, CSS, University of the Punjab, Lahore)
September 27, 2023
Introduction
This lecture is based on health demography. Health is a leading
characteristic of the members of any population. Therefore, its
importent to study the population in cotext with health statistics.
Health is an important correlate of other demographic and
socioeconomic characteristics as well.
Health statistics are often used in interpreting trends in mortality
and in designing assumptions for making projections of mortality.
Health has often been the subject of inquiry in population surveys
and censuses.
Extension of Population Health
In recent decades, the conceptualization of population health has
extended beyond measures of mortality (e.g., life expectancy, infant
mortality) to include specific health measures such as the incidence or
prevalence of morbid conditions, or summary measures of health such as
healthy life expectancy and health-related quality of life.
This extension of population health is due in part to secular trends
of increased life expectancy, which has shifted the focus of population
health from the quantity of life to the quality of life, defined in a
number of different ways.
Summary Measures of Population Health
The World Health Organization (WHO) and various research
organizations have worked to develop and promote summary measures of
population health that combine measures of mortality and measures of
health conditions to represent the state of a population’s health in a
single number.
Summary measures of population health are important because of the
various types of potential applications, as enumerated by Murray,
Salomon, and Mathers (1999, pp. 3–4):
1. Comparing the health of one population with the health of another
population
2. Comparing the health of the same population at different points
in time
3. Identifying and quantifying health inequalities within
populations
4. Providing appropriate and balanced attention to the effects of
nonfatal health conditions on overall population health
5. Informing debates on priorities for health service delivery and
planning
6. Informing debates on priorities for research and development in
the health sector
7. Improving professional training curricula in public health
8. Analyzing the benefits of health interventions for use in
cost-effectiveness analyses
Global Health Policy Initiatives
In addition, the WHO has initiated a new global health policy that
aims to meet the major health problems and issues in the new century.
The health policy initiative, “Health for All in the 21st Century”
(HFA), was established to improve global health and reduce health
inequities within and between countries through the development of
health priorities and targets for the first two decades of the 21st
century.
Member countries have been encouraged to set their own goals in
relation to the HFA goals. In the United States, “Healthy People 2010”
has been launched to meet two overarching goals: to increase the quality
of the years lived and years of healthy life, and to eliminate health
disparities (U.S. Department of Health and Human Services, 2000a,
p. 2).
DEFINITION OF CONCEPTS - Health
Health is a complex and multifaceted concept that is challenging to
define precisely due to its multidimensional nature and social
influences.
The World Health Organization (WHO) established a comprehensive
definition of health in its Constitution in 1946: “Health is a state of
complete physical, mental, and social well-being and not merely the
absence of disease or infirmity.”
Over the years, the definition of health has undergone both
broadening and narrowing interpretations. For example, Mahler (1981)
expanded the concept, while Dubos (1968) provided a narrower
perspective, defining health as “a modus vivendi enabling imperfect
individuals to achieve a rewarding and relatively pain-free existence
while navigating an imperfect world.”
Despite efforts to quantify health status, it is often assessed
indirectly through measures related to its converse, such as disease
prevalence, disability rates, and mortality statistics.
DEFINITION OF CONCEPTS - Health Conditions
In the realm of health, several terms are used to describe states of
less than optimal well-being, including disease, illness, health
condition, and morbid condition. These terms often overlap in their
definitions, making it essential to clarify their distinctions.
Disease and Illness
Disease primarily refers to the biophysical state
of ill health. It focuses on the physiological and pathological aspects
of a health condition.
On the other hand, illness is the social and
personal experience of being sick or diseased. It encompasses the
emotional, psychological, and social dimensions of one’s health.
Morbidity
Morbidity is a broad term encompassing any health
condition. This includes a wide range of states, such as diseases,
injuries, and impairments.
Morbidity can be further categorized into two main types:
Acute Conditions: (Asthma attack, Broken bone,
Bronchitis, Burn, COVID-19,Common cold, Flu, Heart attack.) These
conditions, including acute illnesses and injuries, typically have a
rapid onset, a relatively short duration, and tend to result in either
recovery or death.
Chronic Conditions: Chronic conditions involve a
lengthy period of evolution and progression, possess a long duration,
and are often considered relatively resistant to treatment. For example,
infectious diseases are usually classified as acute, while
cardiovascular diseases fall under the category of chronic
conditions.
Impairments
Impairments represent chronic conditions that
involve abnormalities in body structure and appearance. Among the most
common types are musculoskeletal conditions. Musculoskeletal conditions
are typically characterized by pain, reducing people’s ability to work
and participate in society
Comorbidity
Comorbidity is a term used to describe the presence
of multiple chronic conditions in one individual. It highlights the
complexity and interconnectedness of various health conditions within a
person’s overall health status.
Classification of Morbid Conditions and Disabilities
National governments commonly use classifications for morbid
conditions that are periodically updated by the World Health
Organization (WHO). These updates occur approximately every 10 to 20
years.
The tenth revision, known as ICD-10 (International
Statistical Classification of Diseases and Related Problems, 10th
Edition), was published by the WHO between 1992 and 1994.
However, as of 1998, the ninth revision (ICD-9) was still predominantly
in use, with the United States transitioning to ICD-10 in 1999.
Mental Health Classification
The ICD also includes classifications for mental illnesses alongside
physical illnesses. Chapter V of ICD-10, titled “Mental
and Behavioral Disorders,” not only provides clinical descriptions but
also diagnostic guidelines.
In the United States, mental health conditions are also classified
in a separate publication known as The Diagnostic and
Statistical Manual of Mental Disorders (DSM-IV, American Psychiatric
Association, 1994). Importantly, the codes and terms in DSM-IV
are fully compatible with ICD-10.
Clinicians classify mental disorders based on observations related
to clinical syndromes, personal disorders, physical disorders, the
severity of psychosocial stressors, and the individual’s highest level
of adaptive functioning during the previous year.
Disabilities
A disability refers to either an acute or chronic
condition that hinders an individual’s ability to function and carry out
daily activities.
U.S. National Health Interview Survey
According to the U.S. National Health Interview
Survey, disability is defined as “any temporary or long-term
reduction in a person’s activity due to an acute or chronic condition.”
Essentially, it encompasses the consequences of health conditions.
It is valuable to differentiate between disabilities that can be
partially or entirely managed with technological devices and community
structural changes and those that cannot. This differentiation aids in
defining the severity of disability, ranging from slight to moderate to
severe.
Epidemiological Studies
Epidemiological studies focus on understanding the
distribution of diseases, injuries, and impairments within human
populations and identifying potential risk factors associated with
them.
The primary goal of epidemiological studies is to uncover the
determinants of diseases and develop strategies for disease prevention
and control. These studies play a crucial role in the field of community
or population medicine, where the community is the central concern.
Types of Epidemiological Studies
There are various types of epidemiological studies, each with its
own variations and applications.
Case-Control Studies
In case-control studies, a group of individuals
with a particular disease under investigation is compared to a group of
healthy individuals (the controls). These groups are matched based on
criteria such as age, sex, race, and socioeconomic characteristics.
The objective of case-control studies is to identify characteristics
that differentiate the two groups, shedding light on potential risk
factors for the disease.
Longitudinal Studies
In longitudinal studies, researchers select a group
without the specific disease of interest. Initial data is collected,
including demographic, socioeconomic, and health-related information.
This group is then followed over time to observe who develops the target
disease and to identify any distinguishing characteristics.
When the same individuals are studied over time, it is termed a
panel study. When the study focuses on the same
population but may include different individuals, it is referred to as a
cohort study.
Hybrid Studies
Some epidemiological studies combine elements of both case-control
and longitudinal studies, making them more flexible and adaptable to
specific research questions.