Question

A one page paper on Health Status and why it is important to measure?

Answer 1

Ans) In 1948, WHO defined health as “a state of complete physical, mental and social well-being, and not merely the absence of disease”. Health can be considered in terms of a person’s body structure and function and the presence or absence of disease or signs (health status); their symptoms and what they can and cannot do i.e. the extent to which the condition affects the person’s normal life (quality of life).

- Health care is the prevention, treatment, and management of illness and the preservation of health through the services offered by health care organisations and professionals.

- It includes all the goods and services designed to promote health, including “preventive, curative and palliative interventions, whether directed to individuals or to populations”.[6]

Measures of health status:

- Health status can be measured using pathological and clinical measures and is usually observed by clinicians or measured using instruments.

Types of disease measurement include:

Signs - blood pressure, temperature, X-ray, tumour size
Symptoms - disease specific checklists
Co-morbidity - Charlson Index, ICED- index of co-existing disease (looks at both disease severity and functional severity), adverse events – pain, bleeding, readmission, complications (e.g. using Clavien-Dindo Classification of Surgical Complications).
It is always best to use an existing measure which has been tried and tested rather than inventing a new one. Use an existing standardised measure with proven reliability, validity and responsiveness. Criteria which should be applied when evaluating measures include:

Psychometric criteria

Acceptability - there should be a range across a measure with no floor or ceiling bias
Reliability - test re-test (testing and retesting would give the same score), inter-rater (2 people assessing someone separately would give the same score- measured by the Kappa statistic*), internal consistency (Cronbach’s alpha - when series of questions are used to measure something e.g. the Oxford Hip Score, scores for the answers are often on a scale and added up to give a single total numerical value. Scales must have internal consistency i.e. the items should all measure the same thing. Cronbach’s alpha is a coefficient for assessing internal consistency of a scale. [7])
Validity – sensitivity (identify those with disease correctly) and specificity (identify those without the disease correctly)
Responsiveness - the degree to which a measure can detect change which is clinically meaningful.
*The kappa statistic measures inter-rate reliability. Kappa = (% observed agreement between observers – % agreement expected by chance alone) / (100% - % agreement expected by chance alone).

Practical criteria

If the measure is intended for routine use as part of clinical practice:

The measure should be appropriate/relevant
The measure should be brief and simple to administer
Feasible for routine use.
If it is not possible to use an existing measure, the next best thing is to adapt an existing measure, however it must be re-evaluated for reliability, validity and responsiveness in the new circumstances. Otherwise, a new measure needs to be developed and evaluated for reliability, validity and responsiveness.

Factors that can improve a test’s reliability include:

Training of observers
Clear definitions of terminology, criteria and protocols
Regular observation and review of techniques
Identifying causes of discrepancies and acting on them.
Methods that can increase validity include:

Structured and standardised procedures for collecting clinical information
Standardised protocols for scoring and interpreting
Use of well-constructed instruments (i.e. with documented reliability and validity)
Obtain appropriate reports of information.
Relationship between validity and reliability

What may be valid for a group or a population may not be so for an individual in a clinical setting. When the reliability or repeatability of the test is poor, the validity of the test for a given individual may also be poor.