Treatment of Chronic Obstructive Pulmonary Disease and Its Comorbidities
Fabrizio Luppi1,
Francesca Franco2,
Bianca Beghé1 and
Leonardo M. Fabbri1
1 Department of Respiratory Diseases, University of Modena and Reggio Emilia, Modena, Italy; and 2 Department of Internal Medicine, C. Magati Hospital, Scandiano, Reggio Emilia, Italy
Correspondence and requests for reprints should be addressed to Leonardo M. Fabbri, M.D., Department of Respiratory Diseases, University of Modena and Reggio Emilia, Via del Pozzo, 71, 41100 Modena, Italy. E-mail: leonardo.fabbri{at}unimore.it
ABSTRACT
While chronic obstructive pulmonary disease (COPD) is stillcharacterized and diagnosed by lung function measurements, thereis increasing evidence that the chronic diseases that frequentlydevelop with COPD in response to the common risk factors (smoking,aging, obesity) may contribute significantly to its clinicalmanifestations and severity. Considering that pharmacologicand nonpharmacologic treatments of COPD, such as pulmonary rehabilitation,are primarily symptomatic, it is reasonable to hope that a morecomprehensive management of COPD that takes into account itscomorbidities may improve the response to treatment and reducemortality in patients with COPD. Thus, as comorbidities areoften underdiagnosed and undertreated, it is important to searchfor their coexistence in COPD and in all chronic diseases, possiblyby adopting recommendations for diagnosis of single diseases.This means that while careful cardiovascular, metabolic, andendocrinologic examinations should be increasingly used in assessingpatients with COPD, lung function measurements may become usefulin patients with chronic cardiovalscular, metabolic, and endocrinologicdiseases. The increasing evidence that active treatment of comorbidities(by, e.g., statins and β-blockers) may reduce morbidityand mortality in patients with COPD suggests the urgent needfor randomized clinical trials that hopefully will provide theevidence for more comprehensive clinical guidelines for thesepatients.
Chronic diseases make up a huge proportion of human illness.It has been estimated that in 2005 more than 35 million peopledied from heart disease, stroke, cancer, and other chronic diseases(1–3). Cardiovascular diseases, chronic respiratory diseases,and diabetes are the most frequent chronic degenerative disorders,particularly in the elderly; more than half of all elderly peoplehave at least three chronic medical conditions, and a significantproportion have five or more (4), that are often unrecognizedand untreated (5). Because of an expected sharp increase inchronic diseases in the next 10 years, this is an importantarea of concern for health authorities (1–3, 6). Chronicdiseases share largely preventable risk factors, in particularpoor socioeconomic conditions, poor diet, smoking, obesity,and hypertension (7).
Chronic diseases such as chronic heart failure (CHF) and chronicobstructive pulmonary disease (COPD) often develop togetherwith one or more co-morbid conditions and never alone (7, 8).Not only may a coexisting chronic disease contribute to theclinical manifestations and the severity and life expectancyof the patients (9), but it may also influence the efficacyand safety of patient management. While common clinical practiceis to treat chronic disease as a single condition, there isan urgent need to update the terminology and classification,and to develop new criteria for the diagnosis, assessment ofseverity, and management of patients with multiple chronic diseases.
COPD AND ITS CHRONIC COMORBIDITIES
COPD is still defined as a disease state characterized by poorlyreversible airflow limitation induced by cigarette smoke and/orother noxious particle and gases, and spirometry is recommendedto establish the diagnosis and assess the severity of airflowlimitation (10). However, spirometric assessment poorly correlateswith the clinical manifestations of COPD, and a large proportionof smokers with chronic respiratory symptoms do not meet thespirometric criteria (11, 12).
Cigarette smoking, the most important and best-established riskfactor for COPD, is also a major risk factor for all other chronicdiseases and cancer, not only because it damages the lung directly,but also because it may simultaneously cause systemic effectsaffecting all organs (13, 14).
The most common comorbidities of COPD that are possibly relatedto the systemic effects of smoking are CHF, arrhythmias, hypertension,peripheral and coronary artery diseases, diabetes and metabolicsyndrome, osteoporosis, cancer (particularly lung cancer), pulmonaryvascular abnormalities, psychiatric disorders, cachexia, skeletalmuscle abnormalities, and infections (7, 15, 16).
Thus, the systemic effects of smoking may significantly contributenot only to the respiratory abnormalities, symptoms, and functionalimpairment associated with COPD, but also to the clinical respiratoryand nonrespiratory clinical manifestations related to the chronicdiseases often associated with COPD (7, 17). Low-grade systemicinflammation induced by smoking and other risk factors has alsobeen implicated in the pathogenesis of cardiovascular eventsand chronic myopathy of the skeletal muscle; since patientswith COPD suffer from excess morbidity and mortality relatedto cardiovascular events, it has been suggested that systemicinflammation may be the common link (18).
COPD is an independent risk factor for cardiovascular disease(19). Arterial wall stiffness, which relates to cardiovascularrisk, is increased in patients with COPD compared with controlsubjects who smoke (20, 21). This suggests that COPD may resultin systemic endothelial dysfunction, which may be a mechanismfor the enhanced cardiovascular risk in COPD (19). Systemicarterial wall stiffness is also independently related to emphysemaas assessed by CT scanning (22, 23) and correlates with osteoporosis,another systemic complication of COPD (20). These studies raisethe intriguing possibility that mechanisms that result in alveolarwall destruction and emphysema may also produce increased cardiovascularrisk and osteoporosis in patients with COPD.
Comorbidities are highly likely to affect health outcomes inCOPD, and patients with COPD are more likely to die of cardiovascularcomplications or cancer than of respiratory failure (24). Progressiverespiratory failure accounts for approximately one third ofCOPD-related deaths; therefore, factors other than the progressionof lung disease must play a substantial role.
The number of preexisting comorbidities in patients with COPDis associated with increased in-hospital mortality (25). Co-morbidconditions that have been associated with an increased mortalityrisk in patients with COPD include chronic renal failure, corpulmonale (26), and pulmonary vascular disease. Underlying heartdiseases have not been consistently associated with a highermortality risk. However, because COPD is frequently underreported,it is difficult to make an accurate estimate of how co-morbidconditions influence COPD mortality or, conversely, how COPDaffects the outcome of other diagnoses (24).
In addition to smoking, the other major risk factor for cardiovascularand other chronic co-morbid conditions is obesity (27, 28).Although obesity by itself may affect lung function (29), itsrelationship with COPD has been poorly investigated and is stillunclear. However, obesity may affect respiratory function ina number of ways. Multiple cross-sectional studies have demonstratedan inverse relationship between FEV1 and body mass index (30).This is of particular importance because FEV1 is an independentpredictor of all-cause mortality (31) and a strong risk factorfor cardiovascular disease, stroke, and lung cancer (32). Thus,considering the frequent comorbidities, the concept of COPDas a disease diagnosed and monitored with lung function (e.g.,FEV1) is becoming outdated and likely compromises patient care.It is suggested that patients would benefit from an earlier,broad-based, and aggressive approach to management (33).
COPD AS A COMORBIDITY OF OTHER CHRONIC DISEASES
Smoking and obesity are the two major risk factors for chronicdiseases (34, 35). Obese individuals who smoke have a markedlyreduced life expectancy, and smoking and obesity may interactsynergistically in a vicious circle at different levels andwith different mechanisms, causing endothelial dysfunction andcardiovascular disease (35, 36). Both obesity and smoking areassociated with insulin resistance, oxidative stress, and increasedconcentrations of various (adipo) cytokines and inflammatorymarkers, all of which ultimately lead to endothelial dysfunctionand cardiovascular diseases (30). Consequently, weight losscan reverse many of these problems.
On the other side (vide infra), cachexia and even low body weightin patients with COPD are associated with impaired pulmonarystatus, reduced diaphragmatic mass, lower exercise capacity,and higher mortality rate when compared with adequately nourishedindividuals with this disease. Nutritional support may thereforebe a useful part of their comprehensive care (37, 38).
Patients with peripheral and coronary artery diseases (39, 40),CHF (41), increased cardiovascular risk (20), diabetes and metabolicsyndrome (42), cerebrovascular disorders (43), cancer (44) (particularlylung cancer [45]), osteoporosis (46–48), chronic inflammatorybowel diseases (49, 50), chronic renal failure (51, 52), rheumatoidarthritis (53), psoriasis (54), and premature aging (55) directlyor indirectly share the same major risk factors, particularlysmoking and aging (56–58), and/or have an increased riskof developing COPD.
CLINICAL GUIDELINES FOR COPD AND CHRONIC DISEASES
Clinical practice guidelines have been shown to significantlyimprove the quality of clinical care. However, most guidelinesignore the fact that the majority of individuals with a chronicdisease have one or more comorbidities. COPD, CHF, peripheralartery disease, diabetes, and non–life-threatening cancerhave a major impact on individuals with a chronic condition,particularly in the elderly. Also, adhering to current clinicalpractice guidelines in caring for an older person with severalcomorbidities may have undesirable effects (4). Randomized clinicaltrials provide the evidence supporting clinical guidelines,but because of inclusion/exclusion criteria, randomized clinicaltrials conducted in patients with chronic disease select subjectswho are younger and have milder disease, and exclude those withsignificant comorbidities (59). Thus, clinical practice guidelinesdo not provide adequate guidance for patients with complex chronicdiseases (4, 60), and a more comprehensive approach is recommended(61).
According to the most recent clinical guidelines for COPD (62–64),the available treatments, both pharmacologic and nonpharmacologic,are essentially symptomatic, with the exception of two interventionsthat may also increase life expectancy: smoking cessation inall patients with COPD, and long-term oxygen treatment in patientswith COPD and respiratory failure.
The main achievable goals of COPD management today include relieffrom symptoms, improvement of exercise tolerance and qualityof life, and prevention and management of exacerbations. Thesegoals can be achieved by reduction of risk factors, managementof stable COPD and its comorbidities, and prompt recognitionand management of COPD exacerbation (62–64).
Prevention is important in COPD. Smoking cessation is the mosteffective intervention to reduce symptoms and to decrease therisk of development and progression of COPD (65) and almostall other chronic diseases (66). Pharmacotherapy (nicotine replacement,buproprion/nortryptiline, and/or varenicline) may help patientsstop smoking (67). As part of prevention, protection from occupational,indoor, and outdoor pollution is recommended, although soliddata on the effects of this type of intervention are lacking.
Pharmacologic treatment may relieve symptoms, reduce the frequencyand severity of exacerbations, improve health status, and improveexercise tolerance. Although the mechanisms are poorly understood,bronchodilators, particularly inhaled bronchodilators, are centralto pharmacologic management of COPD, both on an as-needed basisto relieve intermittent or worsening symptoms, and on a regularbasis to suppress persistent symptoms and prevent exacerbations.Nonpharmacologic treatment includes rehabilitation, oxygen therapy,and surgical interventions (62–64), all of which providerelief from symptoms and may also increase life expectancy.
In the following sections we discuss the potential effects ofa more comprehensive approach to the treatment of COPD, by analyzingthe evidence suggesting that (1) treatments for COPD may positivelyaffect morbidity and mortality linked to comorbidities of COPD,and (2) treatments for comorbidities may positively affect morbidityand mortality linked to COPD. We do not discuss (1) mechanismsof symptomatic effects (e.g., potential effects of differenttreatments on respiratory symptoms or exacerbations), (2) adverseeffects of treatments of COPD on comorbidities (e.g., systemicsteroids used for COPD exacerbations in patients with COPD anddiabetes), or (3) adverse effects of treatment of comorbiditieson COPD (e.g., β-blockers in patients with both asthmaand COPD).
EFFECTS OF TREATMENT OF COPD ON ITS COMORBIDITIES
There is evidence to suggest that some interventions in patientswith COPD may affect mortality because of their effects on co-morbidconditions.
Smoking Cessation
Anthonisen and coworkers (68) showed in a 14.5-year follow-upof patients with COPD examined in the Lung Health Study, thatsmoking cessation reduces all-cause mortality, even when successfulin only a minority of participants.
Interestingly, the main effect of smoking cessation is on mortalitydue to myocardial infarction and cancer. Indeed, the leadingcauses of death in the Lung Health Study were lung cancer andcoronary heart disease, and smoking cessation was of benefitin both (Figure 1). This confirms the findings of previous cohortand case-control studies that showed a decline in death fromcoronary heart disease and lung cancer after smoking cessation.Importantly, these results suggest that mechanisms by whichsmoking induces coronary events and lung cancer are apparentlyreversible to some extent, at least in the short term.
Figure 1. Mortality rates at 14.5 years by cause and smoking status, suggesting that in chronic obstructive pulmonary disease (COPD) patients' smoking cessation reduces mortality by cardiovascular diseases and cancer more than by lung diseases. (Reproduced by permission from Reference 68.)
Rehabilitation
Pulmonary rehabilitation is an essential component of the comprehensivemanagement of patients with symptomatic COPD (69). Rehabilitationincludes teaching and supervising of respiratory therapy techniques(e.g., oxygen, inhalers and nebulizers, breathing techniques,chest physical therapy, postural drainage), exercise conditioning(upper and lower extremities), and activities of daily living(work simplification, energy conservation) (63). Pulmonary rehabilitationcan change outcomes that predict survival (70) and can improvethe systemic component of COPD and its comorbidities with apotential effect on survival (71). Because exercise trainingis the most important component of a pulmonary rehabilitationprogram, and because comorbidities are very frequent in patientsundergoing rehabilitation (72), the positive effect of exercisetraining on cardiovascular (73), metabolic (74, 75), and endocrine(e.g., osteoporosis) (76) components is highly likely.
Supplemental Oxygen Therapy
Long-term supplemental oxygen therapy reduces mortality fromall causes in patients with hypoxemic COPD (77, 78), but whetherit specifically reduces cardiovascular, respiratory, metabolic,or cancer mortality is not known. However, in addition to itseffect on mortality, long-term oxygen therapy reduces dyspnea,polycythemia, pulmonary artery pressures, sleep disorders, nocturnalarrhythmias, and neuropsychiatric abnormalities and improvesexercise tolerance, suggesting that its effects go far beyondthe lungs (79, 80). An interesting model comes from the evidencethat oxygen therapy improves renal function in patients withCOPD (81).
Pharmacologic Treatment
The first and only COPD randomized clinical trial to addressthe effect of pharmacologic combination therapy with salmeteroland fluticasone on overall mortality in COPD was the TORCH trial(Toward a Revolution in COPD Health [82]). The study initiallyinvolved 6,112 patients with moderate-to-severe COPD, and itsprimary endpoint was to compare the effect of salmeterol/fluticasoneversus placebo on all-cause mortality over 3 years. The effecton all-cause mortality almost reached statistical significance.Interestingly, careful analysis of the cause of individual deathsby a panel of experts showed that—in this population—thecause-specific mortality was 27% cardiovascular, 35% respiratory,21% cancer, 10% other, and 8% unknown. Forty percent of deathswere definitely or probably related to COPD (83). In addition,the effect of combination treatment, although statisticallynot significant, was almost equally distributed between respiratoryand other causes, suggesting that this treatment also has nonpulmonaryeffects.
The effects of inhaled steroids on mortality in patients withCOPD is controversial. A pooled analysis, based on intentionto treat, of individual patient data from seven randomized trialsof at least 12 months' duration in patients with stable COPDsuggested that inhaled corticosteroids may markedly reduce all-causemortality (84). However, the 3-year prospective TORCH studynot only did not confirm the effect on mortality, but it showeda trend toward increased mortality in patients treated withinhaled corticosteroids alone. This striking discrepancy shouldfurther recommend that retrospective analysis be consideredpurely hypothesis generating, rather than solid evidence.
EFFECT OF TREATMENTS OF COMORBIDITIES ON COPD
Pharmacologic treatment of chronic disease is complex, especiallyconsidering that drugs are usually developed for single diseases.However, drugs designed for one specific disease may also favorablyaffect other diseases. For example, glucose control with insulinor oral antidiabetic agents not only controls diabetes, butalso prevents systemic effects and comorbidities (85). Similarly,treatments for CHF may positively influence arterial hypertension(86), and antihypertensive agents used to control blood pressuremay prevent coronary and cerebrovascular disease (87). Thus,considering that pharmacologic interventions may indeed reducemortality from cardiovascular and metabolic diseases, and consideringthe increased risk of patients with COPD to have these chronicdiseases as well, it seems reasonable to recommend a carefulsearch for these comorbidities in patients with COPD, followedby proper treatment. Also, interestingly, some of these agents,used in particular for cardiovascular diseases, have been recentlyfound in retrospective analyses to have the potential of positivelyaffecting COPD. As with the above-mentioned example of inhaledcorticosteroids, these retrospective studies should be consideredonly hypothesis generating, as the confirmatory evidence shouldcome from prospective randomized clinical trials.
Statins
A large case-control study has shown that statins, angiotensin-convertingenzyme inhibitors (ACEs), and angiotensin receptor blockers(ARBs) may have dual cardiopulmonary protective properties,thereby substantially altering the prognosis of patients withCOPD (88).The combination of statins and ACE inhibitors or ARBswas associated with a reduction in COPD hospitalization andtotal mortality in all patients with COPD, in both the highand the low cardiovascular risk cohorts. Furthermore, this drugcombination reduced myocardial infarction in the COPD cohortwith high cardiovascular risk. Benefits were similar when steroidusers were included (Figure 2). Statins may also reduce thedecline in pulmonary function, independently of the underlyinglung disease (89). In another case-control study, statins evenappeared to protect against the development of lung cancer (90).
Figure 2. Fully adjusted risk ratios are plotted for the end points of hospitalization for COPD, myocardial infarction, death, and myocardial infarction or death. Treatments analyzed were angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARB), statins, and the combination of statins with ACE inhibitors or angiotensin receptor blockers (combination) in the population of patients with COPD with prior revascularization (high risk). (Reproduced by permission from Reference 88.)
Statins are used primarily as lipid-lowering agents in the treatmentof metabolic syndrome, but they also have potent antiinflammatoryproperties that might explain their positive effect on frequentcomorbidities of both metabolic syndrome, for example, CHF andvascular disease, and COPD (91–94). The interest in theseagents was further enhanced by the discovery that statins maycause regression of atherosclerosis lesions (95, 96) (Figure 3),an effect that has not previously been observed in COPD withany intervention, not even after successful smoking cessation(97).
Figure 3. Example of regression of atherosclerosis induced by statin treatment in a patient in the ASTEROID trial. EEM = external elastic membrane. (Reprinted by permission from Reference 95.)
Considering that statins' effects on mortality, even in subjectsat risk of developing cardiovascular diseases (98, 99), significantlyreduces cardiovascular morbidity and mortality, the resultsof these studies on cardiovascular diseases increase the hopesof reducing mortality from other chronic diseases, such as COPD.
ACEs and ARBs
As previously mentioned, Mancini and colleagues showed thatthe combination of statins and ACE inhibitors or ARBs is associatedwith a reduction in COPD hospitalization and total mortalityin all patients with COPD (88) (Figure 2). The renin-angiotensinsystem plays a key role in maintaining blood pressure homeostasis,as well as fluid and salt balance. Angiotensin II, a key effectorpeptide of the system, causes vasoconstriction and exerts multiplebiological functions. ACE plays a central role in generatingangiotensin II from angiotensin I, and capillary blood vesselsin the lung are one of the major sites of ACE expression andangiotensin II production in the human body. The rennin–angiotensinsystem has been implicated in the pathogenesis of pulmonaryhypertension and fibrosis, both of which potentially developin COPD (100) Also, in COPD the sympathetic nervous system,as well as the renin–angiotensin system, may be activatedwith possible negative systemic effects on skeletal muscles(101). Angiotensin II type-1 receptor blockers inhibit the sympatheticand renin–angiotensin systems and might thus improve skeletaland respiratory muscle strength in patients in whom these systemsare activated. Unfortunately, angiotensin II receptor blockadeby irbesartan given over 4 months did not modify respiratorymuscle strength in patients with COPD (102). However, the observedchanges in hematocrit and lung volumes suggest that there werepotential direct beneficial effects to the lung in patientswith COPD, which, combined with the recognized effects on cardiovascularcomorbidities of COPD, might help to modify the natural courseof the disease.
β-Blockers
β-blockers improve health outcomes in patients with cardiovasculardisease, and are recommended as first-line therapy for CHF,a frequent comorbidity of COPD. However, there is some concernthat prescribing β-blockers for patients with COPD maycause bronchoconstriction and worsen respiratory symptoms, eventhough there is increasing evidence that cardioselective βblockade is quite safe in patients with COPD. In fact, a recentmetaanalysis that evaluated the relationship between cardioselectiveβ-blockers and COPD found no significant differences inFEV1 or respiratory symptoms between those treated with a cardio-selectiveβ-blocker and those treated with a placebo, even in patientswith severe COPD (103–105). The analysts concluded that,given their demonstrated benefit in conditions such as heartfailure, coronary artery disease, and hypertension, cardioselectiveβ-blockers should not be routinely withheld from patientswith COPD.
Two recent studies suggested that β-blockers may, in fact,have positive effects in patients with COPD with cardiovasculardiseases. Dransfield and coworkers examined a large populationof inpatients admitted for acute exacerbations of COPD, andfound that the use of β-blockers was associated with reducedin-hospital mortality. The benefit of β-blockers was observeddespite the fact that those who received the drugs were older,had longer hospital stays, and had a greater prevalence of congestiveheart failure and cerebrovascular disease, all factors thatare independent predictors of in-hospital mortality (106). vanGestel and colleagues showed that the use of cardioselectiveβ-blockers is associated with reduced mortality in patientswith COPD undergoing vascular surgery, and suggested that inselected patients with COPD, the use of cardioselective β-blockersmay be safe and associated with reduced mortality (107).
Neurohumoral activation in patients with COPD, similar to thatin CHF and other diseases, may have negative effects such assystemic inflammation, cachexia, effects on ventilation, andskeletal muscle dysfunction, that might explain the increasedcardiovascular morbidity and mortality in patients with COPD.Thus, β-blockers and other agents that are now proved tobe well tolerated in COPD, such as ARBs or ACEs (see above),might have unexpected beneficial effects on COPD and its comorbidities(101).
Treatments for other important comorbidities of COPD, such ascachexia, anemia, and chronic renal failure, should be exploredfurther.
The causes of cachexia in patients with COPD are multifactorialand include decreased oral intake, increased work of breathingdue to abnormal respiratory mechanics, and chronic systemicinflammation and comorbidities (37, 38). While active nutritionalsupplementation in undernourished patients with COPD may leadto weight gain and improvements in respiratory muscle functionand exercise performance, a recent metaanalysis provided noevidence that nutritional support has a significant effect onanthropometric measures, lung function, or exercise capacityin patients with stable COPD (108). In contrast, repeated administrationof ghrelin, a novel growth hormone–releasing peptide thatis reduced in COPD (109), may improve body composition, musclewasting, and functional capacity in cachectic patients withCOPD, suggesting the possibility of reversing some of the systemicaspects of COPD (110). In conclusion, it remains unknown whetherlong-term weight gain by using enhanced caloric intake, withor without anabolic steroids or appetite stimulants, furtherssurvival or provides other benefits to patients with COPD. However,there are indications from single-center trials that this isan avenue well worth exploring (37).
Anemia frequently occurs in patients with COPD, and inadequatehemoglobin levels could aggravate tissue hypoxia and have anegative prognostic impact (111, 112). Blood cell transfusionin anemic patients with COPD reduces minute ventilation andthe work of breathing (113), suggesting that correcting lowhemoglobin levels could alleviate dyspnea and improve exercisecapacity. In a small set of anemic ventilator-dependent patientswith COPD, raising hemoglobin levels to more than 12 g/dl seemedto improve patients' breathing enough to make ventilator weaningpossible (114).
Chronic renal failure is a gradual and progressive loss of theability of the kidneys to excrete wastes, concentrate urine,and conserve electrolytes. It may range from mild dysfunctionto severe renal failure and end-stage renal disease, which isassociated with significant comorbidities (51, 115). Diabetesand hypertension (high blood pressure) account for the majorityof cases of chronic renal failure and end-stage renal disease,and both renal failure and ischemic heart disease are highlyrelevant to the prognosis of patients with COPD discharged fromthe hospital after an acute exacerbation. These co-morbid diseasesprobably act as markers of frailty by increasing the fatalityrate of later COPD exacerbations (116).
CONCLUSIONS
As mentioned, most clinical practice guidelines ignore the factthat the majority of individuals with a chronic disease haveone or more chronic comorbidities (e.g., CHF, peripheral arterydisease, diabetes, or non–life-threatening cancer), thatmay have a major impact on COPD and on chronic diseases in general(9). Thus, although comorbidities are quite common in patientswith COPD, most recent evidence-based guidelines provide littleguidance in caring for patients with COPD with multiple chronicdiseases (62–64). Most patients with chronic diseasesare given multidrug regimens, which clearly provide added disease-specificbenefits for at least some subpopulations of patients, unlikesingle-drug therapy. Less clear, however, are the long-termnet benefits and harm associated with the combination of medicationsthat are taken in adherence to disease-specific guidelines bypatients with several coexisting health conditions (117, 118).Thus, as comorbidities are often underdiagnosed and undertreated,it is important to search for their co-existence with COPD andwith all chronic diseases, possibly by adopting recommendationsfor the diagnosis of single diseases. This means that, whilecareful cardiovascular, metabolic, and endocrinologic examinationsshould be increasingly used in assessing patients with COPD,lung function measurements may be useful in patients with chroniccardiovascular, metabolic, and endocrinologic diseases as well.
Considering that pharmacologic (62–64), and even nonpharmacologictreatment of COPD such as pulmonary rehabilitation (69), areprimarily symptomatic, and considering the frequent chroniccomorbidities of COPD (7), it is reasonable to hope that a morecomprehensive approach to COPD together with its comorbiditiesmay identify novel targets for treatment and modify the naturalcourse of the disease (60, 61). This is particularly relevantfor those conditions that appear more preventable and treatablethan COPD, such as cardiovascular and metabolic disorders. Theincreasing evidence that treatment of comorbidities may reducemorbidity and mortality in patients with COPD suggests the urgentneed for randomized clinical trials that hopefully will providethe evidence for more comprehensive clinical guidelines forthese patients.
ACKNOWLEDGMENTS
The authors are indebted to M. McKenney for editing the manuscriptand to E. Veratelli for her scientific secretarial assistance.
FOOTNOTES
Conflict of Interest Statement: F.L. does not have a financialrelationship with a commercial entity that has an interest inthe subject of this manuscript. F.F. does not have a financialrelationship with a commercial entity that has an interest inthe subject of this manuscript. B.B. does not have a financialrelationship with a commercial entity that has an interest inthe subject of this manuscript. L.M.F. reports having servedas a consultant to Altana Pharma, AstraZeneca, Boehringer Ingelheim,Chiesi Farmaceutici, GlaxoSmithKline, Merck Sharp & Dohme,Novartis, Roche, and Pfizer. He has been paid lecture fees byAltana Pharma, AstraZeneca, Boehringer Ingelheim, Chiesi Farmaceutici,GlaxoSmithKline, Merck Sharp & Dohme, Novartis, Roche, andPfizer. He has received grant support from Altana Pharma, AstraZeneca,Boehringer Ingelheim, Menarini, Miat, Schering Plough, ChiesiFarmaceutici, GlaxoSmithKline, Merck Sharp & Dohme, UCBPharma, Pfizer, Italian Ministry of Health, and Italian Ministryfor University and Research.
(Received in original form September 3, 2008; accepted in final form September 9, 2008)
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