RevPortPneumol.2015;21(5):227---229
www.revportpneumol.org
EDITORIAL
Impaired
function
in
the
complex
patient
with
COPD:
a
matter
to
be
considered
Theveryfrequentassociationbetweenchronicobstructive pulmonarydisease(COPD)andotherchronicdisorders shar-ingcommonriskfactors,1hasbeenwidelyrecognizedasa
majorburdenonindividualsandhealthcaresystems.Ifwe exclude lung cancer, the mostcommon co-existing condi-tions that can be objectively measured in COPD patients arecardiovasculardiseases,typeIIdiabetes,skeletal mus-cledysfunctionandosteoporosis,whicharerepresentedin differentclusters.2
Inthelastfewyearstheterm‘‘comorbidities’’hasbeen replacedby‘‘multimorbidities’’tobetterreflectthenature of this link, with clear reference to a shared pattern of metabolicabnormalities,systemicinflammationanddefined riskfactorsthatidentifiesCOPDasonecomponent-not nec-essarilythemostrelevant -oftheclinical phenotypeof a chroniccomplexpatient.1
In a recent study,Miller et al.demonstrated that car-diovasculardiseasesanddiabeteshave thehighestimpact onseveralpatient-relatedoutcomesinCOPDpatients,even afteradjustingforage,sexandsmokinghistory.3Asamatter
of fact, the mutual interaction between COPD and car-diac dysfunction is based not only on similar risk factors and pathobiological features such as systemic inflamma-tion, but also on pathophysiological mechanisms such as lung hyperdistension,4 which may impairboth ventilatory
and cardiac function during effort, thus limiting exercise performancebothatmaximalorsubmaximallevel.In par-ticular, the dynamic hyperinflation on exertion found in COPD patients with different degrees of airflow obstruc-tion,isassociatedwithareductionofcardiacoutputduring exercise, limiting both venous return and left ventricle filling volume.5 On the other hand, it has been shown
that airflow limitation could negatively impact exercise capacityandphysicalperformanceinpatientswithchronic heart failure.6 Systemichypertension hasbeen relatedto
theincreasedinflammatorysubset observedinCOPD;7 the
DOIoforiginalarticle:
http://dx.doi.org/10.1016/j.rppnen.2015.04.003
correlation between hypertension, higher degree of dys-pneaandreducedphysicalactivityhasalsobeenreported.8
Thisseemsevenmoreimportantifweconsidertheeffect of hypertension on coronary artery disease progression and left ventricular dysfunction, with worsening in exer-cise tolerance.9 Furthermore, Watz et al. showed that
thepresenceof themetabolic syndrome---wheresystemic hypertension and diabetes coexist- among COPD patients is definitely associated with impaired level of physical activity.10
In this issue of the journal, Da Silva and co-workers conducted a cross-sectional study to investigate to what extentthe presenceof co-existinghypertension, coronary heartdiseaseanddiabetes mayaffectfunctionalcapacity in a cohort of 79 patients with COPD.11 These
comor-biditieshave been chosen fromothers according to their higher prevalence in the population of COPD12 and
rele-vant effect on major outcomes. Patients were classified ashaving‘‘none’’, ‘‘one’’, and ‘‘twoor three’’of these comorbidities,andtheindividual’s functionalcapacityhas beenmeasuredobjectivelybymeansofspirometryand six-minutewalkeddistance (6MWT).Aswell astheperceived healthstatus,6MWTdecreasedprogressivelyfrom‘‘none’’ to ‘‘two or three’’ categories (see Fig. 1). Interestingly, thenumberofcomorbiditiesofinterestwasindependently associatedwiththesubmaximalexerciseperformanceafter adjustingformainconfounders(age,severityofCOPD,and scoreofhealthstatus).
Thesefindingsneedtobediscussedinmoredepth,ideally aspectssuchasweaknessandstrengthshouldbeaddressed andclarifiedforthereaders.
Inlinewithpreviousliterature,3authorsconfirmthelack
ofassociationbetweenthedegreeofairflowobstructionand thenumberofconcomitantdisorders.However,thisstudy onlyprovidestheevidenceabout3comorbidities,although theyarethemost important,which relatetothe individ-ual’sfunction.Impaired6MWTand6MWT-derivedvariables (speed,work,exercise-inducedoxygensaturation)havean additional predictive value of mortality in patients with COPD,13 howeverthisperformancecouldbeinfluencedby
http://dx.doi.org/10.1016/j.rppnen.2015.08.001
228 EDITORIAL 400 25 20 15 350 Meters CA T score 300 None One
6MWT distance covered CAT scores
More than two
Fig.1 Relationshipbetweennumberofthe(considered)comorbiditiesandfunctionalimpairmentasassessedbyhealthstatus CATscore(fromref#11).
other coexisting diseases (i.e. musculoskeletal disorders) andfactorsthathave notbeen takenintoaccountbythe authors. In addition, noinformation was given about the severityofeachofthese3comorbidities,noraboutongoing therapiesformanagingthem.
Werecognizethathypertension,coronaryheartdisease anddiabetesarefrequentformsofmultimorbidity influenc-ingtheindividual’sfunctionassinglediseasesorclustering together.3,8,14 Indeed, authors have confirmed that these
chronic diseases have a negative impact on the exercise capacity, here recorded as both the reduction in meters walkedandtheincreasedscoresoftheitemsassessing func-tionintheCOPDAssessmentTest(CAT).Therefore,accurate assessmentandcountofcomorbiditiesinthe characteriza-tionof patients withCOPD contribute to predicting their outcomesandriskofmortality.12
Another problem with the present data might be that thepresence of hypertension,coronaryheart diseaseand diabeteswasself-reportedand/orderivedbytheassumed medications,therewasnoobjectiveassessment.Recently, ithasbeenshownthatself-reportingmayresultin underes-timationofchronicdiseasesandmultimorbidity.15
Walkingperformance,however,doesnotexclusively rep-resentthe functional capacityof patients withCOPD.We canonly speculate onwhether thereis direct correlation between6MWTand theindividual’s physical activity (PA), since a good degree of exercise tolerance is pivotal to performing complex kinds of activities in daily living. In COPDsubjects,lowerlevelsofPAareassociatedwithhigher degreeofseverity16andaworseprognosis.17Adeclinetolow
PAovertimeisassociatedwithanincreasedmortalityrisk inthosewithCOPDbutalsothosewithout.18 Thissuggests
thatitisimportanttoassessandencouragePAinthe ear-lieststagesofCOPDin ordertomaintainitat thehighest possiblelevel, asthis isassociated withbetterprognosis. However,PAcannotbederivedbythesubmaximalexercise testintheCOPDpopulation,nordidauthorsmeasurePAin theirstudysample.Adeeperdiscussionontheexistinglinks betweenexercise performance andPA shouldbe takenin consideration in ordertounderstand theextent towhich other chronic co-existing diseases might limit function in patientswithCOPD.
Thecumulativeeffectofmultimorbidityinlimiting phys-ical performance should be carefully considered when a
COPD patient is assessed and managed, paying particular attentiontorehabilitation.To date,pulmonary rehabilita-tion,including exercisetraining, hasproved to beone of themosteffectivetherapiesforCOPDpatients.19,20
Further-more,recentstudieshaveshownthatevenchangesinthe level of activity following rehabilitation have direct pro-portional effects on major outcomes in these patients.18
At present, some retrospective studies have shown worse outcomes (in terms of exercise tolerance, and perceived well-being) in COPD patients with associated heart and metabolic diseases undergoing pulmonary rehabilitation, while others reported the opposite effect.21 The reason
behindthisdifferencemightbethehigherdegreeof impair-mentinthesepatientswhoaregenerallymoredyspnoeic3
andlessphysicallyactive.22 However,evidencefrom
avail-able literature is incomplete and there is a need for adjunctive datatounderstand the effective roleof coex-istingdiseasesonrehabilitationoutcomesinthepopulation ofCOPD.Foragivendifferentpatternofresponseto exer-ciseinthecomplexpatients,atailoredinterventioncouldbe thussupposedasmostimportant.Althoughthelinkbetween co-existing diseases and reduced performanceduring pul-monaryrehabilitationhasbeen clearlyshown,thepresent studybyDaSilva11didnotconsiderthisaspect.
Inconclusion, taking all the limitations of the present study into account, results corroborate actual debate around the impactof COPD-associated multimorbidity on physical performanceand theconsequenceswhen a phys-icaltherapy isappliedtopatients.The topicseemstobe ofcriticalimportanceinordertoensurethemosteffective andpersonalizedtreatmentforCOPDpatientsreferredfor arehabilitationcourse.
References
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2.VanfleterenLE,etal.Clustersofcomorbiditiesbasedon val-idatedobjectivemeasurementsand systemicinflammationin patients with chronic obstructive pulmonary disease. Am J RespirCritCareMed.2013;187:728---35.
3.MillerJ, et al. Comorbidity, systemicinflammation and out-comesintheECLIPSEcohort.RespirMed.2013;107:1376---84.
EDITORIAL 229
4.BarrGR,et al.Percentemphysema,airflowobstruction,and impairedleftventricularfilling.NEnglJMed.2010;362:217---27. 5.TzaniP,etal.Dynamichyperinflationisassociatedwithapoor cardiovascularresponseto exercise inCOPD patients.Respir Res.2011;12:15.
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R.Tonellia, E.M.Clinia,b,∗
aDUofMedicalandSurgicalSciences,Universityof
Modena-ReggioEmilia,Italy
bOspedaleVillaPineta,Pavullon7F(Modena),Italy
∗Correspondingauthor.UniversityofModena-Reggio
Emilia,OspedaleVillaPineta,Pavullon/F(Modena),Italy. Tel.:+39053642039;fax:+39053642039.
