The Measurement of Health and Health Status. Concepts, Methods and Applications from a Multidisciplinary Perspective

347 Pages·2016·8.725 MB·English

by  Paul Krabbe

The Measurement of
Health and Health Status
Concepts, Methods and Applications from
a Multidisciplinary Perspective
Paul F. M. Krabbe
University of Groningen,
University Medical Center Groningen,
Department of Epidemiology (Unit: Patient Centered Health
Technology Assessment)
Groningen, The Netherlands
AMSTERDAMlBOSTONlHEIDELBERGl LONDON
NEWYORKlOXFORDlPARISlSANDIEGO
SANFRANCISCOlSINGAPORElSYDNEYl TOKYO
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Dedication
To my Swedish wife and all my children.
Preface
Youonlyseeitonceyougetit[Jegaathetpaszienalsjehetdoorhebt]JohanCruijff
(iconicDutch soccerplayerandtrainer,1947e2016).
Afterworkingforalmost25yearsontheevaluationofhealthinterventionsin
the setting of university hospitals, I realized that the field of health outcomes
measurementispartitionedoffinsegregatedareas.Thisisparticularlyevident
withrespecttosubjectivephenomenasuchasperceivedhealthstatusor(health-
related)qualityoflife.Someofthosewhoinvestigateorapplytheinstruments
adhere to the framework of psychometrics; others call themselves clinime-
triciansandusedifferentconceptsandmethods;anothergroupconsistsofhealth
economists and decision-science researchers who have their own framework.
Mostofthemareunfamiliarwithotherframeworksandoftennotevenawareof
what these can offer. There is a widespread misunderstanding of the different
approachestoconceptualizeandmeasurehealthandhealthstatus.Mygoalhere
istobringtheseframeworkstogether,astheyarefarmorecloselyconnectedthan
generallyrecognized.
Inspiration for this book was drawn from my own teaching experience but
alsofrommycontactswithnumerousotherscientistsandresearchersinthefield.
In terms of its content, the book is a response to many presentations made by
othersatconferencesdnotareflectionofwhatIlearnedfromtheirpapersbut
ratherofwhatseemedunclearorundefined.Anothersourceofinspirationwas
thestimulatingenvironmentinwhichIhavebeenactivelyengagedformorethan
20 years:theinternationalEuroQolResearchFoundation.Thisgroupbundles
researchersfrom all over theworld with thesame interest,namely tomeasure
“health-relatedqualityoflife”andexpressthisinasinglemetricfigure.Because
EuroQol members come from many different backgrounds, collaboration is
often thought provoking. Despite its diversity, the group works under the um-
brella of the health-economic doctrines that stipulate how health should be
measured.
I hope this book will contribute to the field by unifying material that is
currently dispersed over volumes that treat these measurement approaches
separately. Because it crossesdisciplinaryboundaries,this bookoffersanillu-
minating perspective on the measurement of health. While I recognize
xv
xvi Preface
that health outcomes research uses different types of measuresdincluding
clinical,healthstatus,qualityoflife,andpatientsatisfactiondIhavechosento
focus on health status. Thus, along with the measurement of health, this book
coversthemeasurementof(perceivedorexperienced)healthstatus,inparticular
health-relatedqualityoflife.
Thebookisintendedtoofferreadersasetofdirectionsinaseaofconfusing
concepts to help them select the best measurement framework. Which one is
“best”dependsonthesituation,onwhattheanalystswant,orwhichpolicythey
aretryingtoassess.Inthatrespect,thisbookcomplementsbutalsodistinguishes
itselffromtheliteratureonthistopic.First,itcontainsanintegrativeoverviewof
material from various disciplines and fields. Second, it provides in-depth ex-
planationsoftheprosandconsofspecificmeasurementmethods,highlighting
theirrelationshipsanddifferencesaswellastheircontributions.Third,itavoids
detailed descriptions, though some of the most well-known and frequently
appliedinstrumentsareexplainedanddiscussedtoillustrateapoint.Fourth,it
providesprofessionalswithanoverviewoftheknowledge,language,andcon-
ceptsthatareusedinthisdiverseandfragmentedfield.
Thisbookcannotbeexpectedtoclearupallofthedifficultiesofmeasuringa
subjectivephenomenonsuchashealth.Yet,becauseitisalsointendedtoserveas
anintroductoryhandbook,somecrucialprinciplesarecovered,thoughwithout
presentinglengthymathematicalderivationsorrelyingheavilyonstatistics.On
the other hand, the interpretation of statistical measurement concepts such as
reliability,validity,responsiveness,item-responsetheory,andfactoranalysisis
treatedmoreextensively.Practicalapplicationsandstudyquestions,whichare
usuallyincludedintextbooks,weredeliberatelyleftout.Instead,theconceptual
underpinningofcurrentapproachestomeasurementisillustratedbyempirical
examples. For information on related issues, the reader is referred onward by
citingothersources.
Assuch,thisbookpresentsaunifyingperspectivethatisrelevanttoscientists
and others working in several disciplines and in various fields. The target
audience comprises academics and professionals: medical doctors, health re-
searchers, health-care providers, clinical epidemiologists, health economists,
and insurance providers. The book is also intended for people working in
pharmaceuticalcompanies,intheareasofhealthtechnologyassessment,public
health,nursing,pharmacy,dentistry,healthservicesresearch,physiotherapists,
andoccupationaltherapistsinvolvedindevelopingandusinghealthscales.
It is the elusiveness of health that ensures its enduring appeal to scientific
inquiry.Interdisciplinarycooperationisthebestwayforwardinmanyfields,and
healthmeasurementisnoexception.Ourendeavortoarriveatcrediblemethods
to quantify health calls for contributions from the fields of health economics,
medicine, psychology, measurement theory, mathematics, and others, but also
Preface xvii
frompatients,whoseimportancetoresearchshouldnotbeunderestimated.The
issues and methods addressed here are too complex for the narrow focus of a
singlediscipline.
PaulF.M.Krabbe
UniversityofGroningen,
UniversityMedicalCenterGroningen,
DepartmentofEpidemiology(Unit:PatientCenteredHealth
TechnologyAssessment)
Groningen,TheNetherlands
October2016
Iwelcomeandencouragereaderstowritetheirsuggestionsandcommentsto
[email protected].
Acknowledgments
Scienceisacooperativeenterprise,andassuchmyworkonthemeasurement
of health draws not only on my own ideas. Several other individuals have
shaped my thinking and influenced my work. I should mention George
Torrancefirst,ashewasmyprimaryinspirationwhenIstartedoutinthisfield.
Not only did he introduce new concepts but he could write clear scholarly
articles, many as sole author. He was on the program of the first scientific
conferenceIattendeddin1995inPhoenix,ArizonadandImissedhisplenary
addressbecauseIwasstilldrivingneartheMexicanborderinmyrentalcar(I
had yet to learn that distances in the United States are incomparable to dis-
tances in the Netherlands). But later I was able to meet with George several
times.
In2004IspentsometimevisitinganinstituteatHarvardUniversitywhere
I was hosted by Christopher Murray, who founded the Global Burden of
Disease approach and developed the disability-adjusted life year concept.
After a few days Joshua Salomon stopped by. I was struck by his sound and
balanced reasoning and his multidisciplinary range of interests, impressed by
his detailed knowledge of the origins of many scientific methods and ideas,
and inspired by how he combined these in his own exploration of methods to
measure health status.
But my greatest source of inspiration was Louis Thurstone (1887e1955).
Withamastersinengineering,Thurstone(originallyhisSwedishfamilyname
was Thunstro¨m) began his career as an electrical engineer. Thomas Edison
(known for the phonograph, the motion picture camera, and the electric light
bulb) had heard about Thurstone’s invention of a flicker-free motion picture
projector and offered him an internship. Thurstone was intrigued by Edison:
did Edison’s problem-solving capacity stem from his geniusor did his genius
stemfromhisabilitytosolveproblems?Formanyyears,Thurstoneworkedas
a psychometrician at the University of Chicago. His groundbreaking work on
themeasurementofattitudeslaidthefoundationformeasuringsubjectiveand
social phenomena.
English editing by Nancy van Weesep-Smyth.
xix
Chapter 1
Introduction
Chapter Outline
Introduction 3 PatientReported 7
DefiningHealth 4 PatientCenteredness 8
ImportanceofHealth 5 DigitalRevolution 9
HealthModels 6 References 10
INTRODUCTION
Ask any medical gathering whether 1year of life is about the same as any
other and you will surely hear a resounding chorus of “no.” It is not just the
quantitybutalsothequalityoflifethatconcernspeople,medicalprofessionals
orotherwise.Thisappliestothelifeyearssavedinlife-and-deathsituationsas
much as to interventions explicitly geared to changing morbidity and raising
healthstatus.Soitcanprobablybeagreedthatthemeasurementof“qualityof
life” or “quality of health” is a necessary part of health evaluation (Brooks,
1995).
Althoughtraditionalhealthoutcomessuchasdeadoraliveorsurvivingare
indisputable, these measures are often insufficient when studying chronic
diseases or conditions such as pain, migraine, fatigue, mental status, or
depression.Thatismainlybecausesurvivaldoesnotplayamajorroleinthese
types of problems. In addition, while we can measure a biological response,
we may not be able to determine whether that response makes a noticeable
difference to the patient. For example, when treating anemia (decrease in the
amountofredbloodcells),wecanmeasurehemoglobinlevels,butweshould
also know if the biologic response results in changes such as a perceived
reduction in fatigue.
This realization also has led to changes in health policy. In evaluating
healthcare,thereisanoticeableshiftinemphasisfromtraditional,simple-to-
measure clinical indicators such as mortality and morbidity to more complex
patient-basedoutcomessuchasdisabilityand“qualityoflife.”Forexample,in
theEnglishNationalHealthService,health-statusmeasurementisatthecenter
ofthereformeffort,asseeninthedevelopmentofPROMs(Devlin&Appleby,
2010) (Box 1.1, Fig. 1.1).
TheMeasurementofHealthandHealthStatus.http://dx.doi.org/10.1016/B978-0-12-801504-9.00001-5
Copyright©2017ElsevierInc.Allrightsreserved. 3
4 TheMeasurementofHealthandHealthStatus
BOX1.1
Concerninghappiness,however,andwhatitis,theyareindispute,andordinary
peopledonotgivethesameansweraswiseones.Forordinarypeoplethinkitas
one of the plainly evident things, such as pleasure or wealth or honordsome
taking it to be one thing, others another. And often the same person thinks it as
differentthings,sincewhenheorshegetsadisease,itishealth,whereaswhenhe
orsheispoor,itiswealth.
From Ethica Nichomachea (translation Reeve, C.D.C., 2014. Hackett Publishing Company,
Indianapolis,p.14).
DEFINING HEALTH
Defining health is, at best, problematic. Its definition reflects the historical
period and culture to which it applies. Over the past 150years, rising expec-
tations have changed the definition of health in the United States: from sur-
vival, it shifted to freedom from disease, to an ability to perform daily
activities, and even came to embrace a sense of happiness and well-being.
FIGURE1.1 Aristotle(384e322
BC).
Introduction Chapter j1 5
Americans seem toexpect their health tobe not merely adequate butgood, if
not excellent. Expectations in other cultures are lower. In many African
countries, for example, certain afflictions are so prevalent that they are not
even considered diseases. Drawing the line between being sick or well may
alsodependuponageandsex.Forinstance,theelderlynormallyenduremore
sicknessthantheyoungormiddleaged.Therefore,thedefinitionofhealthfor
an elderly person may include pain and discomfort not experienced by
younger persons. Pregnant women in developing countries do not get the
medical attention that most women in developed countries get and may
therefore undergo more pain and discomfort in pregnancy. Definitions of
health are likely to reflect the ideology and culture of the most powerful
groups in society. In modem societies, there is a tendency to consider more
conditionsasdiseases,suchasalcoholism,drugdependence,anddelinquency.
There is also a greater tolerance of the diseased person (Larson, 1991).
IMPORTANCE OF HEALTH
Abraham Maslow (1908e70) was an American psychologist who is best
known for creating a hierarchy of needs. His theory is often represented as a
pyramid with five hierarchical levels (Fig. 1.2). Based on motivational theory
in psychology, it presumes that once people have met their basic needs, they
seek tomeet successivelyhigher needs. Maslowcalled the bottom four levels
ofthepyramid“deficiencyneeds”:apersondoesnotfeelanythingiftheyare
met but becomes anxious if they are not. Thus, physiological needs such as
eating,drinking,andsleepingaredeficiencyneeds,asaresafetyneeds,social
Self-actualization
self-fulfilment, altruism,
spirituality, creativity, acceptance
of facts, lack of prejudice Higher
level
needs
Self-esteem
confidence, achievement,
Deficiency respect of others
needs
Love and belonging
friendship, family, intimacy, sense of connection
Safety
health, employment, resources, morality, social stability
Physiological
food, water, sleep, breathing, shelter, clothing Basic
needs
FIGURE1.2 Maslow’shierarchyofneeds.