Value of C-reactive protein measurements in exacerbations of chronic obstructive pulmonary disease

Antibiotics

This chapter describes the optimal approach to antibiotic treatment of exacerbations recognizing these limitations. Such an approach relies upon an accurate diagnosis of an exacerbation, including judicious application of diagnostic tests. Determining the severity of an exacerbation follows this. If antibiotics are indicated, then a risk stratification approach is described to choose an appropriate antibiotic. An increase in airway inflammation from the baseline level in a patient appears central to the pathogenesis of most acute exacerbations. Airway inflammation measured in induced or expectorated sputum, bronchoalveolar lavage or bronchial biopsy has revealed that increased inflammation accompanies exacerbations and resolves with treatment. Potential pathogens in chronic obstructive pulmonary disease (COPD) exacerbations include typical respiratory bacterial pathogens, respiratory viruses, and atypical bacteria. The current model of bacterial exacerbation pathogenesis involves both host and pathogen factors. Acquisition of strains of bacterial pathogens that are new to the host from the environment is the primary event that puts the patient with COPD at risk for an exacerbation. The traditional aims of treatment of an exacerbation are improvement in clinical status and the prevention of complications. The role of antibiotics in the treatment of COPD exacerbations has been a matter of controversy. Even more contentious has been the issue whether antibiotic choice is relevant to clinical outcome of exacerbations. Recommendations for antibiotic use among published guidelines are inconsistent.

Acute exacerbations and respiratory failure in chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) describe the phenomenon of sudden worsening in airway function and respiratory symptoms in patients with COPD. These exacerbations can range from self-limited diseases to episodes of florid respiratory failure requiring mechanical ventilation. The average patient with COPD experiences two such episodes annually, and they account for significant consumption of health care resources. Although bacterial infections are the most common causes of AECOPD, viral infections and environmental stresses are also implicated. AECOPD episodes can be triggered or complicated by other comorbidities, such as heart disease, other lung diseases (e.g., pulmonary emboli, aspiration, pneumothorax), or systemic processes. Pharmacologic management includes bronchodilators, corticosteroids, and antibiotics in most patients. Oxygen, physical therapy, mucolytics, and airway clearance devices may be useful in selected patients. In hypercapneic respiratory failure, noninvasive positive pressure ventilation may allow time for other therapies to work and thus avoid endotracheal intubation. If the patient requires invasive mechanical ventilation, the focus should be on avoiding ventilator-induced lung injury and minimizing intrinsic positive end-expiratory pressure. These may require limiting ventilation and "permissive hypercapnia." Although mild episodes of AECOPD are generally reversible, more severe forms of respiratory failure are associated with a substantial mortality and a prolonged period of disability in survivors.

Inhaled and systemic corticosteroids in chronic obstructive pulmonary disease

Systemic and local inflammation is central to the pathophysiology of chronic obstructive pulmonary disease (COPD). Increased levels of inflammation have been linked to a more progressive course in COPD and have been shown to be present during an exacerbation. Decreases in inflammatory cytokines, C-reactive protein, and inflammatory cells have been observed with corticosteroid use, suggesting a possible mechanism for a therapeutic benefit of steroids. No available data support the routine use of systemic corticosteroids in stable COPD; however, short courses during exacerbations are likely to improve length of hospitalization, lung function, and relapse rate. Inhaled corticosteroids (ICS) decrease the rate of exacerbation and may improve the response to bronchodilators and decrease dyspnea in stable COPD. No study shows that ICS reduce the loss of lung function; however, recent data suggest a possible survival benefit when combined with long-acting beta agonists. There are limited data on the use of ICS in the treatment of acute exacerbations of COPD, and its role in this setting must be more clearly defined. The empiric use of systemic corticosteroids perioperatively represents another area of uncertainty. The role of pharmacogenetics in the metabolism of corticosteroids in COPD is evolving but may be partially responsible for the observed variability in patient responsiveness. The potential benefits of systemic or inhaled corticosteroid use must be weighed against the risk of known toxicities.

Cardiac disease in chronic obstructive pulmonary disease

The cardiac manifestations of chronic obstructive pulmonary disease (COPD) are numerous. Impairments of right ventricular dysfunction and pulmonary vascular disease are well known to complicate the clinical course of COPD and correlate inversely with survival. The pathogenesis of pulmonary vascular disease in COPD is likely multifactorial and related to alterations in gas exchange and vascular biology, as well as structural changes of the pulmonary vasculature and mechanical factors. Several modalities currently exist for the assessment of pulmonary vascular disease in COPD, but right heart catheterization remains the gold standard. Although no specific therapy other than oxygen has been generally accepted for the treatment of pulmonary hypertension in this population, there has been renewed interest in specific pulmonary vasodilators. The coexistence of COPD and coronary artery disease occurs frequently. This association is likely related to shared risk factors as well as similar pathogenic mechanisms, such as systemic inflammation. Management strategies for the care of patients with COPD and coronary artery disease are similar to those without COPD, but care must be given to address their respiratory limitations. Arrhythmias occur frequently in patients with COPD, but are rarely fatal and can generally be treated medically. Use of beta-blockers in the management of cardiac disease, while a theoretical concern in patients with increased airway resistance, is generally safe with the use of cardioselective agents.

Optimizing antibiotic selection in treating COPD exacerbations

Our understanding of the etiology, pathogenesis and consequences of acute exacerbations of chronic obstructive pulmonary disease (COPD) has increased substantially in the last decade. Several new lines of evidence demonstrate that bacterial isolation from sputum during acute exacerbation in many instances reflects a cause-effect relationship. Placebo-controlled antibiotic trials in exacerbations of COPD demonstrate significant clinical benefits of antibiotic treatment in moderate and severe episodes. However, in the multitude of antibiotic comparison trials, the choice of antibiotics does not appear to affect the clinical outcome, which can be explained by several methodological limitations of these trials. Recently, comparison trials with nontraditional end-points have shown differences among antibiotics in the treatment of exacerbations of COPD. Observational studies that have examined clinical outcome of exacerbations have repeatedly demonstrated certain clinical characteristics to be associated with treatment failure or early relapse. Optimal antibiotic selection for exacerbations has therefore incorporated quantifying the risk for a poor outcome of the exacerbation and choosing antibiotics differently for low risk and high risk patients, reserving the broader spectrum drugs for the high risk patients. Though improved outcomes in exacerbations with antibiotic choice based on such risk stratification has not yet been demonstrated in prospective controlled trials, this approach takes into account concerns of disease heterogeneity, antibiotic resistance and judicious antibiotic use in exacerbations.

The value of C-reactive protein as a marker of systemic inflammation in stable chronic obstructive pulmonary disease

BACKGROUND

Systemic aspects of chronic obstructive pulmonary disease (COPD) include oxidative stress and altered circulating levels of inflammatory mediators and acute-phase proteins. C-reactive protein (CRP) reflects total systemic burden of inflammation in several disorders and has been shown to upregulate the production of proinflammatory cytokines. The aim of this study was to evaluate circulating CRP levels to determine the value of CRP as a biomarker of systemic inflammation and as an indicator of malnutrition or severity of COPD in stable COPD patients in comparison to the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6).

METHODS

Thirty-five male patients with stable COPD and 30 age- and sex-matched subjects with normal pulmonary function were admitted to the study. Serum CRP levels were measured using a commercially available kit with the turbidimetric method. Serum TNF-alpha and IL-6 concentrations were measured with ELISA kits.

RESULTS

Sixty percent of the patients had severe or very severe and 40% moderate COPD. Serum CRP was significantly higher in stable COPD patients than in control subjects (p<0.001), while TNF-alpha and IL-6 concentrations were not statistically different. Serum TNF-alpha was higher in severe or very severe COPD patients (p=0.046). When the COPD patients with a low BMI were compared to those with a normal-to-high BMI, there was a significant difference in CRP (p=0.034) and TNF-alpha (p=0.037).

CONCLUSION

The present study confirms that circulating CRP levels are higher in stable COPD patients and may thus be regarded as a valid biomarker of low-grade systemic inflammation. In addition, CRP is significantly higher in COPD patients with a low BMI and thus, together with TNF-alpha, may be considered an indicator of malnutrition in COPD patients.

C-reactive protein levels in patients with chronic obstructive pulmonary disease: role of infection

OBJECTIVE

To investigate the value of C-reactive protein (CRP) as a marker of chronic obstructive pulmonary disease (COPD) exacerbations or specifically bacterial exacerbations and to evaluate a correlation between raised CRP levels and other markers of inflammation in patients with an acute exacerbation (AECOPD).

SUBJECTS AND METHODS

The medical records of patients with AECOPD were retrospectively analyzed. They were categorized according to the nature of sputum as mucoid or purulent and to the findings on chest radiographs as with pneumonia (PCOPD) or without pneumonia. Stable COPD (SCOPD) patients and a group of asymptomatic nonsmokers were also included in the study.

RESULTS

All COPD patients (SCOPD: 30; AECOPD: 51; PCOPD: 32) and control subjects (30) were male. The mean CRP levels and WBC counts of the groups were PCOPD: 108.1 +/- 61.8 mg/l and 13.7 +/- 6.8 x 10(9)/l; AECOPD: 36.8 +/- 43.9 mg/l and 11.4 +/- 4.8 x 10(9)/l; SCOPD: 3.9 +/- 1.4 mg/l and 7.9 +/- 1.9 x 10(9)/l; control: 2.1 +/- 0.9 mg/l and 7.7 +/- 1.1 x 10(9)/l. The mean CRP level of AECOPD was statistically different from those of PCOPD and SCOPD (p = 0.0001, p = 0.002, respectively). The sensitivity and specificity of CRP to determine an acute exacerbation were 72.5 and 100%, respectively. Among the patients with AECOPD, 25 had purulent sputum and a mean CRP level of 46.4 +/- 48.6 mg/l, which is significantly higher than the CRP level (28.0 +/- 44.5 mg/l) of the 18 patients with mucoid expectoration (p = 0.015). Among the mucoid-expectorating subgroup, the patients with leukocytosis had significantly higher CRP levels than the patients without leukocytosis (p = 0.034).

CONCLUSION

A high serum CRP value may indicate an infectious exacerbation in COPD patients and it correlates with sputum purulence and increased serum WBC counts.

Role of macrolide therapy in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of death and disability worldwide. The Global Burden of Disease study has concluded that COPD will become the third leading cause of death worldwide by 2020, and will increase its ranking of disability-adjusted life years lost from 12th to 5th. Acute exacerbations of COPD (AECOPD) are associated with impaired quality of life and pulmonary function. More frequent or severe AECOPDs have been associated with especially markedly impaired quality of life and a greater longitudinal loss of pulmonary function. COPD and AECOPDs are characterized by an augmented inflammatory response. Macrolide antibiotics are macrocyclical lactones that provide adequate coverage for the most frequently identified pathogens in AECOPD and have been generally included in published guidelines for AECOPD management. In addition, they exert broad-ranging, immunomodulatory effects both in vitro and in vivo, as well as diverse actions that suppress microbial virulence factors. Macrolide antibiotics have been used to successfully treat a number of chronic, inflammatory lung disorders including diffuse panbronchiolitis, asthma, noncystic fibrosis associated bronchiectasis, and cystic fibrosis. Data in COPD patients have been limited and contradictory but the majority hint to a potential clinical and biological effect. Additional, prospective, controlled data are required to define any potential treatment effect, the nature of this effect, and the role of bronchiectasis, baseline colonization, and other cormorbidities.

Inflammatory profile of new bacterial strain exacerbations of chronic obstructive pulmonary disease

RATIONALE

Whether the airway and systemic inflammatory profile in bacterial exacerbations of chronic obstructive pulmonary disease (COPD) is distinct from nonbacterial exacerbations is unclear. Previous studies have not used molecular typing of bacterial pathogens, which is required to accurately define bacterial infection in COPD. The relationship between clinical severity and course of exacerbation and inflammation is also not fully understood.

OBJECTIVES

To determine if (1) systemic and airway inflammation is distinct in new bacterial strain exacerbations and (2) clinical severity and resolution of exacerbations is related to airway and systemic inflammation.

METHODS

In a prospective longitudinal cohort study in COPD, sputum and serum samples obtained before, at, and following exacerbations during a 2-year period were studied.

MEASUREMENTS AND MAIN RESULTS

Clinical information, molecular typing of bacterial pathogens, sputum IL-8, tumor necrosis factor (TNF)-alpha and neutrophil elastase, and serum C-reactive protein. From 46 patients, 177 exacerbations were grouped as new strain, preexisting strain, other pathogen, and pathogen negative. New strain exacerbations were associated with significantly greater increases from baseline in sputum TNF-alpha and neutrophil elastase, and in serum C-reactive protein compared with the other three groups. Increases in inflammatory markers were similar among the other three groups. Clinical resolution was accompanied by resolution of inflammation to preexacerbation levels, whereas persistent symptoms were paralleled by persistently elevated inflammation. Clinical exacerbation severity was significantly correlated with levels of all four markers.

CONCLUSIONS

Neutrophilic airway inflammation and systemic inflammation are more intense with well-defined bacterial exacerbations than with nonbacterial exacerbations. Clinical course of exacerbation and inflammation are closely linked.

Pathogen-directed therapy in acute exacerbations of chronic obstructive pulmonary disease

Acute exacerbations of chronic obstructive pulmonary disease (COPD) are important events in the natural history of this chronic lung disorder. These events can be caused by a large number of infectious and noninfectious agents and are associated with an increased local and systemic inflammatory response. Their frequency and severity have been linked to progressive deterioration in lung function and health status. Infectious pathogens ranging from viral to atypical and typical bacteria have been implicated in the majority of episodes. Most therapeutic regimens to date have emphasized broad, nonspecific approaches to bronchoconstriction and pulmonary inflammation. Increasingly, therapy that targets specific etiologic pathogens has been advocated. These include clinical and laboratory-based methods to identify bacterial infections. Further additional investigation has suggested specific pathogens within this broad class. As specific antiviral therapies become available, better diagnostic approaches to identify specific pathogens will be required. Furthermore, prophylactic therapy for at-risk individuals during high-risk times may become a standard therapeutic approach. As such, the future will likely include aggressive diagnostic algorithms based on the combination of clinical syndromes and rapid laboratory modalities to identify specific causative bacteria or viruses.

Serum amyloid a is a biomarker of acute exacerbations of chronic obstructive pulmonary disease

RATIONALE

Much of the total disease burden and cost of chronic obstructive pulmonary disease (COPD) is associated with acute exacerbations of COPD (AECOPD). Serum amyloid A (SAA) is a novel candidate exacerbation biomarker identified by proteomic screening.

OBJECTIVES

To assess SAA as a biomarker of AECOPD.

METHODS

Biomarkers were assessed (1) cross-sectionally (stable vs. AECOPD; 62 individuals) and (2) longitudinally with repeated measures (baseline vs. AECOPD vs. convalescence; 78 episodes in 37 individuals). Event severity was graded (I, ambulatory; II, hospitalized; III, respiratory failure) based on consensus guidelines.

MEASUREMENTS AND MAIN RESULTS

Presumptively newly acquired pathogens were associated with onset of symptomatic AECOPD. In the cross-sectional study, both SAA and C-reactive protein (CRP) were elevated at AECOPD onset compared with stable disease (SAA median, 7.7 vs. 57.6 mg/L; P < 0.01; CRP median, 4.6 vs. 12.5 mg/L; P < 0.01). Receiver operator characteristics analysis was used to generate area-under-curve values for event severity. SAA discriminated level II/III events (SAA, 0.88; 95% confidence interval, 0.80-0.94 vs. CRP, 0.80; 95% confidence interval, 0.70-0.87; P = 0.05). Combining SAA or CRP with major symptoms (Anthonisen criteria, dyspnea) did not further improve the prediction model for severe episodes. IL-6 and procalcitonin were not informative.

CONCLUSIONS

SAA is a novel blood biomarker of AECOPD that is more sensitive than CRP alone or in combination with dyspnea. SAA may offer new insights into the pathogenesis of AECOPD.

Longitudinal follow-up of systemic inflammation after acute exacerbations of COPD

BACKGROUND

Acute exacerbations are important in the clinical course of COPD, yet the underlying mechanisms are poorly understood. Systemic inflammation is now considered as an important component in the disease process. In this study we evaluated longitudinally the systemic inflammation during hospital treatment for acute exacerbation and after clinical recovery.

METHODS

Blood was collected on day 0, 1, 4 and 8 in 21 patients admitted for an acute exacerbation of COPD and at 1 month, 3 months and 6 months after discharge. Systemic inflammation was determined by measurement of the pro-inflammatory markers interleukin (IL)-6, soluble tumor necrosis factor (TNF) receptors sTNFR55 and sTNFR75, the anti-inflammatory mediator sIL-1RII, and bactericidal permeability increasing protein (BPI) as a marker of neutrophil activation. In addition, plasma level of Trolox antioxidant capacity (TEAC) was determined. Healthy age-matched controls were measured for the same markers at one time-point.

RESULTS

All inflammatory markers analyzed were elevated on first day of admission for exacerbation of COPD, as compared to healthy controls. During treatment, levels of IL-6, and sTNFR75 rapidly decreased, whereas sTNFR55 and BPI remained elevated. Moreover, sIL-1RII and TEAC increased during first 8 days of treatment. In the stable condition all inflammatory markers returned to values comparable to healthy controls, with the exception of BPI, which remained persistently elevated compared to healthy controls.

CONCLUSION

This study clearly demonstrates upregulation of systemic inflammation in acute exacerbations of COPD. Attenuation of systemic inflammation may offer new perspectives in the management of COPD patients to reduce the burden of exacerbations.

Influenza and COPD mortality protection as pleiotropic, dose-dependent effects of statins

BACKGROUND

Published data on antiinflammatory and immunomodulatory effects of statins suggest they may reduce mortality risks associated with an unchecked immune response to selected infections, including influenza and COPD. We assessed whether statin users had reduced mortality risks from these conditions.

METHODS

We conducted a matched cohort study (n = 76,232) and two separate case-control studies (397 influenza and 207 COPD deaths) to evaluate whether statin therapy is associated with increased or decreased mortality risk and survival time using health-care encounter data for members of health maintenance organizations. For the cohort study, baseline illness risks from all causes prior to initiation of statin therapy were used to statistically adjust for the occurrence of outcomes after initiation of treatment.

RESULTS

For moderate-dose (>/= 4 mg/d) statin users, this cohort study found statistically significant reduced odds ratios (ORs) of influenza/pneumonia death (OR, 0.60; 95% confidence interval [CI], 0.44 to 0.81) and COPD death (OR, 0.17; 95% CI, 0.07 to 0.42) and similarly reduced survival hazard ratios. Findings were confirmed with the case-control studies. Confounding factors not considered may explain some of the effects observed.

CONCLUSIONS

This study found a dramatically reduced risk of COPD death and a significantly reduced risks of influenza death among moderate-dose statin users.

Copeptin, C-Reactive Protein, and Procalcitonin as Prognostic Biomarkers in Acute Exacerbation of COPD

BACKGROUND

A novel approach to estimate the severity of COPD exacerbation and predict its outcome is the use of biomarkers. We assessed circulating levels of copeptin, the precursor of vasopressin, C-reactive protein (CRP), and procalcitonin as potential prognostic parameters for in-hospital and long-term outcomes in patients with acute exacerbation of COPD (AECOPD) requiring hospitalization.

METHODS

Data of 167 patients (mean age, 70 years; mean FEV(1), 39.9 +/- 16.9 of predicted [+/- SD]) presenting to the emergency department due to AECOPD were analyzed. Patients were evaluated based on clinical, laboratory, and lung function parameters on hospital admission, at 14 days, and at 6 months.

RESULTS

Plasma levels of all three biomarkers were elevated during the acute exacerbation (p < 0.001), but levels at 14 days and 6 months were similar (p = not significant). CRP was significantly higher in patients presenting with Anthonisen type I exacerbation (p = 0.003). In contrast to CRP and procalcitonin, copeptin on hospital admission was associated with a prolonged hospital stay (p = 0.002) and long-term clinical failure (p < 0.0001). Only copeptin was predictive for long-term clinical failure independent of age, comorbidity, hypoxemia, and lung functional impairment in multivariate analysis (p = 0.005). The combination of copeptin and previous hospitalization for COPD increased the risk of poor outcome (p < 0.0001). Long-term clinical failure was observed in 11% of cases with copeptin < 40 pmol/L and no history of hospitalization, as compared to 73% of patients with copeptin >/= 40 pmol/L and a history of hospitalization (p < 0.0001).

CONCLUSIONS

We suggest copeptin as a prognostic marker for short-term and long-term prognoses in patients with AECOPD requiring hospitalization.

Systemic inflammation in COPD: is genetic susceptibility a key factor?

COPD is a multicomponent disease characterized by abnormal inflammatory response of the lungs to noxious particles that is accompanied by systemic effects like weight loss, muscle wasting, reduced functional capacity and impaired health status. A persistent low-grade systemic inflammatory response reflected by enhanced levels of acute phase proteins like C-reactive protein (CRP) and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, is present in part of the COPD population. The production of inflammatory proteins is partly genetically determined. Several studies have shown that polymorphisms within genes coding for these inflammatory mediators may modulate systemic inflammatory responses. Among all of these genes, the TNF family (TNF-alpha, lymphotoxin (LT)-alph and their receptors TNF-R55 and TNF-R75), interleukin (IL)-6 and CRP gene polymorphisms are the most prominent candidates. However, large carefully designed studies in well-characterized COPD cohorts are required to unravel the exact role of genetic background in the systemic component of this disease.

The role of airway secretions in COPD--clinical applications

It has been established that mucus hypersecretion and decreased mucus clearance contribute to the morbidity of chronic obstructive pulmonary disease (COPD). Indeed, the classic definition of chronic bronchitis relies on determining the frequency and duration of sputum expectoration. Despite the well recognized importance of this symptom, there are few therapies routinely used to decrease the sputum production or to improve clearance. There are fewer well conducted clinical trials of existing medications and this has led many regulatory agencies, notably the Food and Drug Administration (FDA), to refuse to register these medications or approve their sale. Similarly, airway clearance devices and chest physical therapy have not been well studied in COPD. Carefully conducted studies of interventions to improve airway clearance, similar to those done in cystic fibrosis (CF), may help us to identify effective therapies and possibly novel diagnostic tests for the management of COPD.

Systemic Cytokines, Clinical and Physiological Changes in Patients Hospitalized for Exacerbation of COPD

BACKGROUND

Systemic inflammation in patients with COPD may worsen during exacerbations, but there is limited information relating levels of systemic inflammatory markers with symptoms and physiologic changes during an exacerbation

METHODS

We measured dyspnea using the visual analog scale, pulmonary function tests, hemograms, and plasma levels for interleukin (IL)-6, IL-8, leukotriene B(4) (LTB4), tumor necrosis factor-alpha, and secretory leukocyte protease inhibitor (SLPI) in 20 patients on admission to a hospital for exacerbation of COPD (ECOPD), 48 h later (interim), and 8 weeks after hospital discharge (recovery).

RESULTS

Dyspnea was present in all patients. Inspiratory capacity improved faster than FEV(1). Compared to recovery, there was a significant increase in the mean (+/- SD) hospital admission plasma levels of IL-6 (6.38 +/- 0.72 to 2.80 +/- 0.79 pg/mL; p = 0.0001), IL-8 (8.18 +/- 0.85 to 3.72 +/- 0.85 pg/mL; p = 0.002), and LTB4 (8,675 +/- 1,652 to 2,534 +/- 1,813 pg/mL; p = 0.003), and the percentages of segmented neutrophils (79 to 69%; p < 0.02) and band forms (7.3 to 1.0%; p < 0.01) in peripheral blood, with no changes in TNF-alpha and SLPI. There were significant correlations between changes in IL-6 (r = 0.61; p = 0.01) and IL-8 (r = 0.56; p = 0.04) with changes in dyspnea and levels of IL-6 (r = -0.51; p = 0.04) and TNF-alpha (r = -0.71; p < 0.02) with changes in FEV(1.)

CONCLUSIONS

Hospitalized patients with ECOPDs experience significant changes in systemic cytokine levels that correlate with symptoms and lung function. An ECOPD represents not only a worsening of airflow obstruction but also increased systemic demand in a host with limited ventilatory reserve.

[Follow-up criteria for community acquired pneumonias and acute exacerbations of chronic obstructive pulmonary disease]

The follow-up of Community Acquired Pneumonias (CAP) and Acute Exacerbations of Chronic Obstructive Pulmonary Diseases (AECOPD) differs with the setting of care, but overall calls upon the same investigations as the initial evaluations. In the event of initial ambulatory care, the evaluation is carried out primarily on clinical data, at the 2 or 3rd day for the CAP, at the 2nd to 5th day for the AECOPD. In the event of unfavourable evolution, or from the start in the most severe cases, the follow-up is carried out in hospital; clinical evaluation is readily daily, and all the more frequent that the clinical condition is worrying because of the severity or risk factors. The investigations will be limited to those initially abnormal in the event of favourable evolution; on the contrary, unfavourable evolution can justify new investigations which depend on clinical characteristics. Remotely, i.e. 4 to 8 weeks later, must be checked the return at the baseline clinical state, a chest X-ray (CAP), spirometry and arterial blood gas (AECOPD), even bronchoscopy and thoracic CT-scan.

Chronic obstructive pulmonary disease: clinical signs and infections

Chronic obstructive pulmonary disease (COPD) is a pathological condition that involves excessive production of mucus, chronic cough and inflammatory changes leading to airway limitation. The most common cause of COPD is cigarette smoking. COPD can be categorized into either chronic bronchitis or emphysema; both conditions can be differentiated by age and the production of copious, tenacious sputum. Patients with COPD are susceptible to pulmonary infections of bacterial or viral origin. Nurses should be aware of the subtle differences in conditions and the usefulness of antibiotics in the treatment of acute bacterial exacerbations of chronic bronchitis.

Use of plasma biomarkers at exacerbation of chronic obstructive pulmonary disease

IMPACT

This study explores the use of measuring plasma biomarkers at exacerbation of chronic obstructive pulmonary disease (COPD), providing insight into the underlying pathogenesis of these important events.

RATIONALE

The use of measuring C-reactive protein (CRP) to confirm exacerbation, or to assess exacerbation severity, in COPD is unclear. Furthermore, it is not known whether there may be more useful systemic biomarkers.

OBJECTIVE

To assess the use of plasma biomarkers in confirming exacerbation and predicting exacerbation severity.

METHODS

We assessed 36 biomarkers in 90 paired baseline and exacerbation plasma samples from 90 patients with COPD. The diagnosis of exacerbation fulfilled both health care use and symptom-based criteria. Biomarker concentrations were related to clinical indices of exacerbation severity. Interrelationships between biomarkers were examined to gain information on mechanisms of systemic inflammation at exacerbation of COPD.

MEASUREMENTS AND MAIN RESULTS

To confirm the diagnosis of exacerbation, the most selective biomarker was CRP. However, this was neither sufficiently sensitive nor specific alone (area under the receiver operating characteristic curve [AUC], 0.73; 95% confidence interval, 0.66-0.80). The combination of CRP with any one increased major exacerbation symptom recorded by the patient on that day (dyspnea, sputum volume, or sputum purulence) significantly increased the AUC to 0.88 (95% confidence interval, 0.82-0.93; p<0.0001). There were no significant relationships between biomarker concentrations and clinical indices of exacerbation severity. Interrelationships between biomarkers suggest that the acute-phase response is related, separately, to monocytic and lymphocytic-neutrophilic pathways.

CONCLUSIONS

Plasma CRP concentration, in the presence of a major exacerbation symptom, is useful in the confirmation of COPD exacerbation. Systemic biomarkers were not helpful in predicting exacerbation severity. The acute-phase response at exacerbation was most strongly related to indices of monocyte function.

Markers of exacerbation severity in chronic obstructive pulmonary disease

Background

Patients with chronic obstructive pulmonary disease (COPD) can experience 'exacerbations' of their conditions. An exacerbation is an event defined in terms of subjective descriptors or symptoms, namely dyspnoea, cough and sputum that worsen sufficiently to warrant a change in medical management. There is a need for reliable markers that reflect the pathological mechanisms that underlie exacerbation severity and that can be used as a surrogate to assess treatment effects in clinical studies. Little is known as to how existing study variables and suggested markers change in both the stable and exacerbation phases of COPD. In an attempt to find the best surrogates for exacerbations, we have reviewed the literature to identify which of these markers change in a consistent manner with the severity of the exacerbation event.

Methods

We have searched standard databases between 1966 to July 2004 using major keywords and terms. Studies that provided demographics, spirometry, potential markers, and clear eligibility criteria were included in this study. Central tendencies and dispersions for all the variables and markers reported and collected by us were first tabulated according to sample size and ATS/ERS 2004 Exacerbation Severity Levels I to III criteria. Due to the possible similarity of patients in Levels II and III, the data was also redefined into categories of exacerbations, namely out-patient (Level I) and in-patient (Levels II & III combined). For both approaches, we performed a fixed effect meta-analysis on each of the reported variables.

Results

We included a total of 268 studies reported between 1979 to July 2004. These studies investigated 142,407 patients with COPD. Arterial carbon dioxide tension and breathing rate were statistically different between all levels of exacerbation severity and between in out- and in-patient settings. Most other measures showed weak relationships with either level or setting, or they had insufficient data to permit meta-analysis.

Conclusion

Arterial carbon dioxide and breathing rate varied in a consistent manner with exacerbation severity and patient setting. Many other measures showed weak correlations that should be further explored in future longitudinal studies or assessed using suggested mathematical modelling techniques.

Role of infection and antimicrobial therapy in acute exacerbations of chronic obstructive pulmonary disease

Over the past several years, the significance of acute exacerbations of chronic obstructive pulmonary disease (AECOPD) in patients with chronic airflow obstruction has become increasingly apparent due to the impact these episodes have on the natural history of disease. It is now known that frequent AECOPD can adversely affect a patient's health-related quality of life and short- and long-term pulmonary function. The economic burden of these episodes is also substantial. AECOPDs represent a local and systemic inflammatory response to both infectious and noninfectious stimuli, but the majority of episodes are likely related to bacterial or viral pathogens. Patients with purulent sputum and multiple symptoms are the most likely to benefit from treatment with antibiotics. Antibiotic choice should be tailored to the individual patient, taking into account the severity of the episode and host factors which might increase the likelihood of treatment failure. Current evidence suggests that therapeutic goals not only include resolution of the acute episode, but also prolonging the time to the next event. In the future, preventing exacerbations will likely become increasingly accepted as an additional therapeutic goal in chronic obstructive pulmonary disease patients.

C-reactive protein--can it be used as a marker of infection in patients with exacerbation of chronic obstructive pulmonary disease?

BACKGROUND

Far from all patients with exacerbation of chronic obstructive pulmonary disease (COPD) benefit from antibiotic treatment. However, as these patients are often colonized with bacteria, even in a stable phase, there is no reliable method for establishing whether the patients have a significant bacterial infection and would benefit from antibiotic treatment. C-reactive protein (CRP) has proven to be useful as a marker of bacterial infection. The aim of this study was to assess to what degree CRP is elevated in patients with exacerbation of COPD.

METHODS

A total of 166 consecutive patients admitted to a department of internal medicine at a university hospital in Copenhagen due to exacerbation of COPD were prospectively included in the study. Patients were asked whether they had experienced increased sputum purulence and whether they were on steroid treatment or not. Blood was drawn for determination of white blood cell count and CRP, and a chest X-ray was taken. Patients whose X-rays of the thorax showed changes compatible with pneumonia were considered to have pneumonia of bacterial origin.

RESULTS

Pneumonia was diagnosed in 51 patients. Their median CRP was 97 mg/l (49-145 interquartile range). Among patients without pneumonia, 46% (51/115) had normal CRP values (0-10 mg/l); 64 had no increased sputum purulence and a median CRP of 8 mg/l (2.9-16 mg/l), which is significantly lower than in the 51 patients who reported increased sputum purulence and had a CRP of 45 mg/l (8.5-86 mg/l; p<0.001).

CONCLUSION

CRP values are normal in nearly 50% of patients admitted due to exacerbation of COPD. In patients who have increased sputum purulence, the pattern of increase in CRP is similar to that seen in patients with pneumonia. This suggests that CRP may be used as a marker of significant bacterial infection. Thus, it may be used when deciding whether or not to start antibiotic treatment. This should be tested in a controlled trial.

Raised CRP levels mark metabolic and functional impairment in advanced COPD

BACKGROUND

C-reactive protein (CRP) is often used as a clinical marker of acute systemic inflammation. Since low grade inflammation is evident in chronic diseases such as chronic obstructive pulmonary disease (COPD), new methods have been developed to enhance the sensitivity of CRP assays in the lower range. A study was undertaken to investigate the discriminative value of high sensitivity CRP in COPD with respect to markers of local and systemic impairment, disability, and handicap.

METHODS

Plasma CRP levels, interleukin 6 (IL-6) levels, body composition, resting energy expenditure (REE), exercise capacity, health status, and lung function were determined in 102 patients with clinically stable COPD (GOLD stage II-IV). The cut off point for normal versus raised CRP levels was 4.21 mg/l.

RESULTS

CRP levels were raised in 48 of 102 patients. In these patients, IL-6 (p<0.001) and REE (adjusted for fat-free mass, p = 0.002) were higher while maximal (p = 0.040) and submaximal exercise capacity (p = 0.017) and 6 minute walking distance (p = 0.014) were lower. The SGRQ symptom score (p = 0.003) was lower in patients with raised CRP levels, as were post-bronchodilator FEV1 (p = 0.031) and reversibility (p = 0.001). Regression analysis also showed that, when adjusted for FEV1, age and sex, CRP was a significant predictor for body mass index (p = 0.044) and fat mass index (p = 0.016).

CONCLUSIONS

High sensitivity CRP is a marker for impaired energy metabolism, functional capacity, and distress due to respiratory symptoms in COPD.

Markers of disease severity in chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES

Diagnosis and assessment of treatment effect in chronic obstructive pulmonary disease (COPD) have relied primarily on the examination of a complex set of symptoms and the use of spirometry. However, these methods require long periods of assessment to determine whether patients show clinically relevant improvements after intervention. We therefore wanted to determine how existing clinical and laboratory measures change with COPD severity and identify disease markers that can serve as better endpoints for diagnosis and assessment of COPD progression and treatment effect.

METHODS

Using standard COPD keywords and terms, we searched PubMed, ISI Web of Science, and Cochrane Review databases for retrospective and prospective clinical studies published since 1966. We identified 652 studies (n = 146,255) from 1978 to September 2003 based on the availability of spirometric and demographic data, investigation of possible markers, absence of acute exacerbations and co-morbidities, and the withdrawal of standard COPD medication. Central tendencies and dispersions of subject baseline measures were collected according to study sample size, smoking status, and mild, moderate and severe COPD stages. A fixed effect meta-analysis was then conducted on each measure at various disease stages.

RESULTS

Arterial oxygen tension, sputum neutrophils and IL-8, and serum TNF-alpha and C-Reactive Protein showed a trend toward separation between COPD stages. Other measures such as pack-years and St George's Respiratory Questionnaire only distinguished between disease and disease-free states.

CONCLUSIONS

We observed little separation between disease stages for many measures used in COPD diagnosis and clinical trials. This demonstrates the poor sensitivity of such endpoints to define a patient's clinical status and to quantify treatment effect. Therefore, we recommend that longitudinal studies and disease modelling be the primary methods for assessing whether potential markers of disease progression can be used for COPD diagnosis and clinical trials.

Modulation of neutrophil and inflammation markers in chronic obstructive pulmonary disease by short-term azithromycin treatment

The anti-inflammatory potential of azithromycin in chronic obstructive pulmonary disease (COPD) patients was explored following a standard oral dosing regimen. Patients with moderate and severe COPD were treated with azithromycin (500 mg, n=16) or placebo (n=8) once daily for 3 days in a randomized, double blind design, to compare effects on inflammation markers with those seen in a previous study in healthy volunteers. A battery of tests was made on serum, blood neutrophils and sputum on days 1 (baseline), 3, 4, 11, 18 and 32. In comparison to placebo, azithromycin resulted in an early transient increase in serum nitrites plus nitrates (day 3), associated with a tendency towards an increase in the blood neutrophil oxidative burst to phorbol myristic acetate. Subsequently, prolonged decreases in blood leukocyte and platelet counts, serum acute phase protein (including C reactive protein) and soluble E-selectin and blood neutrophil lactoferrin concentrations and a transient decrease in serum interleukin-8 were observed. Blood neutrophil glutathione peroxidase activity showed a prolonged increase after azithromycin treatment. The biphasic facilitatory-then-inhibitory response to azithromycin seen in healthy volunteers is not so clearly detectable in COPD patients, only potential anti-inflammatory effects. Treatment for longer periods may give therapeutic anti-inflammatory benefit in these patients.

Acute exacerbations of chronic bronchitis: new developments concerning microbiology and pathophysiology--impact on approaches to risk stratification and therapy

Exacerbations are a characteristic feature of chronic obstructive pulmonary disease and contribute significantly to associated morbidity and mortality. Renewed interest in this common clinical problem and research using new investigative tools has enhanced substantially the understanding of the pathogenesis of exacerbations. Results of recent clinical trials and observational studies have allowed refinements in treatment of exacerbations that should im-prove patient outcomes. This article discusses a rational, stratified approach to the use of antibiotics for this condition based on these recent studies.

Pneumonia in elderly patients with preexisting respiratory disease

To evaluate the optimal duration of appropriate antibiotic therapy for pneumonia in elderly patients with preexisting respiratory disease, we studied improvement of infectious parameters in these patients. The medical record database was used to identify patients admitted with the following characteristics: primary diagnosis of benign respiratory disease; aged 65 years or over; no active malignant diseases in any organs; and at least one admission for pneumonia during April 2001 to May 2003. We observed 47 pneumonia episodes in 30 patients. Elevated CRP levels more than 8.0 mg/ml and leukocytosis more than 10.0 x 10(3) mm(-3) was seen in 21 and 29 pneumonia episodes, respectively. With appropriate intravenous antimicrobial therapy, average of CRP levels on day 0 (9.16 +/- 6.81 mg/dl) decreased to 5.18 +/- 4.67 mg/dl on day 3 (P = 0.0073). In more than 70% of pneumonia episodes, serum levels of CRP normalized on day 10. Average of leukocyte counts on day 0 ((12.3 +/- 4.7) x 10(3) mm(-3)) decreased to (8.1 +/- 3.5) x 10(3) mm(-3) on day 3 (P = 0.0001). In more than 80% of pneumonia episodes, leukocyte count normalized on day 7. The clinical response to appropriate antimicrobial therapy for pneumonia occurs within the first 3 days of therapy. Duration of intravenous antimicrobial therapy for pneumonia in these patients of 10 days would be sufficient and could prevent recurrent infection with resistant bacteria.

Serum procalcitonin and C-reactive protein levels as markers of bacterial infection: a systematic review and meta-analysis

A meta-analysis was performed to evaluate the accuracy of determination of procalcitonin (PCT) and C-reactive protein (CRP) levels for the diagnosis of bacterial infection. The analysis included published studies that evaluated these markers for the diagnosis of bacterial infections in hospitalized patients. PCT level was more sensitive (88% [95% confidence interval [CI], 80%-93%] vs. 75% [95% CI, 62%-84%]) and more specific (81% [95% CI, 67%-90%] vs. 67% [95% CI, 56%-77%]) than CRP level for differentiating bacterial from noninfective causes of inflammation. The Q value for PCT markers was higher (0.82 vs. 0.73). The sensitivity for differentiating bacterial from viral infections was also higher for PCT markers (92% [95% CI, 86%-95%] vs. 86% [95% CI, 65%-95%]); the specificities were comparable (73% [95% CI, 42%-91%] vs. 70% [95% CI, 19%-96%]). The Q value was higher for PCT markers (0.89 vs. 0.83). PCT markers also had a higher positive likelihood ratio and lower negative likelihood ratio than did CRP markers in both groups. On the basis of this analysis, the diagnostic accuracy of PCT markers was higher than that of CRP markers among patients hospitalized for suspected bacterial infections.

COPD exacerbations: the importance of a standard definition

Efforts to assess the efficacy of new therapies in the treatment of acute exacerbations of chronic obstructive pulmonary disease (COPD) have been hampered by the lack of a widely agreed and consistently used definition. A variety of definitions have been used in clinical studies, based on changes in patient symptoms or the requirement for antibiotic therapy, oral steroids or hospitalisation. To date, none of these definitions have been assessed in detail for their reliability, responsiveness and validity determined. Considerable heterogeneity in the aetiology and manifestation of COPD exacerbations makes identification and quantification of defining symptoms extremely difficult. New approaches are therefore being sought with a view to identifying a serum or tissue marker that can be used as a valuable diagnostic tool. Improvements in data recording will also contribute to the accuracy of data retrieval and assessment. If we are to progress to a level of sophistication seen in the diagnosis and management of other diseases, it is evident that considerable research efforts will be required to improve our understanding of COPD exacerbations and develop a standard definition for these events, thereby facilitating the assessment of therapeutic approaches.

Muscle force during an acute exacerbation in hospitalised patients with COPD and its relationship with CXCL8 and IGF-I

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is often associated with peripheral muscle weakness, which is caused by several factors. Acute exacerbations may contribute, but their impact on muscle force remains unclear. Correlations between peripheral muscle force and inflammatory and anabolic markers have never been studied in COPD. The effect of an acute exacerbation on quadriceps peak torque (QPT) was therefore studied in hospitalised patients, and the aforementioned correlations were examined in hospitalised and in stable patients.

METHODS

Lung function, respiratory and peripheral muscle force, and inflammatory and anabolic markers were assessed in hospitalised patients on days 3 and 8 of the hospital admission and 90 days later. The results on day 3 (n=34) were compared with those in clinically stable outpatients (n=13) and sedentary healthy elderly subjects (n=10).

RESULTS

Hospitalised patients had lowest mean (SD) QPT (66 (22)% predicted) and highest median (IQR) levels of systemic interleukin-8 (CXCL8, 6.1 (4.5 to 8.3) pg/ml). Insulin-like growth factor I (IGF-I) tended to be higher in healthy elderly subjects (p=0.09). QPT declined between days 3 and 8 in hospital (mean -5% predicted (95% CI -22 to 8)) and partially recovered 90 days after admission to hospital (mean 6% predicted (95% CI -1 to 23)). QPT was negatively correlated with CXCL8 and positively correlated with IGF-I and lung transfer factor in hospitalised and in stable patients.

CONCLUSIONS

Peripheral muscle weakness is enhanced during an acute exacerbation of COPD. CXCL8 and IGF-I may be involved in the development of peripheral muscle weakness in hospitalised and in stable patients with COPD.

Clinical characteristics and genotype analysis of patients with cystic fibrosis and nasal polyposis

The prevalence of nasal polyps in a group of paediatric patients with cystic fibrosis was prospectively studied in comparison with a control group with cystic fibrosis but without polyps. Clinical variables, including pulmonary function tests, skin testing and mucociliary transport, were carried out in both groups, as well as genotype analysis. Endoscopic intranasal evaluation identified polyps in 29 of 89 patients (33%). Statistical analysis revealed that patients with nasal polyposis had better pulmonary function, a higher rate of Pseudomonas aeruginosa colonization, more hospitalizations, and more prevalence of allergy to Aspergillus fumigatus than did the comparison group. We found no statistically different genotype distribution between the polyposis and the control group. However, it can be emphasized that the prevalence of the compound heterozygous genotype is higher in the nasal polyposis group than in controls. Our observations suggest that other genetic and environmental factors could play an important role in the development of nasal polyposis.

Association between glycemic state and lung function: the Framingham Heart Study

Diabetes mellitus has been inconsistently associated with a reduced level of pulmonary function. To elucidate this association further, we analyzed the relationship of diabetes and of fasting blood glucose to the level of pulmonary function assessed by spirometry in the 3,254 members of the Framingham Offspring Cohort. Diabetes was defined as a fasting blood glucose of 126 mg/dl or more or pharmacologic treatment. Subjects were classified as current, former, or never smokers based on questionnaire responses. Predicted pulmonary function was determined from the coefficients of a regression of pulmonary function on age, sex, and body habitus in the 1,110 never smokers. Both the diagnosis of diabetes and a higher level of fasting blood glucose were associated with lower than predicted levels of pulmonary function. The adverse effect of diabetes and glycemic level on pulmonary function was stronger among ever smokers than never smokers, suggesting an interaction between the level of fasting glycemia and tobacco smoking.

Use of antibiotics in patients admitted to the hospital due to acute exacerbation of chronic obstructive pulmonary disease (COPD)

BACKGROUND: The purpose of this study was to assess to what extent symptoms and signs of bacterial infection are present and evaluated in patients admitted to the hospital for exacerbation of chronic obstructive pulmonary disease (COPD) in relation to initiation of antibiotic treatment. METHODS: All adult patients (>18 years of age) discharged from a department of internal medicine in Copenhagen in 1997 with a diagnosis of exacerbation of COPD were included in our study and their reports were retrospectively reviewed. Gender, age, number of admissions and length of hospital stay, use of antibiotics and steroids prior to admission, temperature, white blood cell (WBC) count, results of lung auscultation and X-ray examination of the thorax at admittance, and growth of sputum culture and antibiotic treatment in the hospital were all registered. RESULTS: A total of 400 admissions took place. In 104 of them, chest X-ray was compatible with pneumonia, and 99 cases were treated with antibiotics. In 44% of the remaining 296 cases, antibiotics were given. It was found that 25-45% of the patients with very little evidence of infection-i.e. the absence of, or only the presence of, one of the following indicators of infection: fever (temperature>37.5 degrees C), a raised WBC count (>9 billion/l), or crepitation at lung auscultation-were given antibiotics. In cases presenting with two or three of these indicators, 50-75% were given antibiotics. In 85% of the cases, penicillin or a macrolide was the initial antibiotic of choice. The median hospital stay was 6 days for the entire group of patients. CONCLUSION: These data suggest that, in patients with acute exacerbation of COPD, a relatively high number of patients with only weak symptoms or signs of bacterial infection are treated with antibiotics.

Disturbances in leptin metabolism are related to energy imbalance during acute exacerbations of chronic obstructive pulmonary disease

Previously we reported an impaired energy balance in patients with chronic obstructive pulmonary disease (COPD) during an acute disease exacerbation, but limited data are available on the underlying mechanisms. Experimental and clinical research supports the hypothesis of involvement of the hormone leptin in body weight and energy balance homeostasis. The aim of this study was to investigate the course of the energy balance in relation to leptin and the soluble tumor necrosis factor (TNF) receptors (sTNF-R) 55 and 75, plasma glucose, and serum insulin in patients with severe COPD during the first 7 d of hospitalization for an acute exacerbation (n = 17, 11 men, age mean [SD] 66 [10] yr, FEV(1) 36 [12] %pred). For reference values of the laboratory parameters, blood was collected from 23 (16 men) healthy, elderly subjects. On admission, the dietary intake/resting energy expenditure (REE) ratio was severely depressed (1.28 [0.57]), but gradually restored until Day 7 (1.65 [0. 45], p = 0.005 versus Day 1). Glucose and insulin concentrations were elevated on admission, but on Day 7 only plasma glucose was decreased. The sTNF-Rs were not different from healthy subjects and did not change. Plasma leptin, adjusted for fat mass expressed as percentage of body weight (%FM), was elevated on Day 1 compared with healthy subjects (1.82 [3.85] versus 0.32 [0.72] ng%/ml, p = 0.008), but decreased significantly until Day 7 (1.46 [3.77] ng%/ml, p = 0. 015 versus Day 1). On Day 7, sTNF-R55 was, independently of %FM, correlated with the natural logarithm (LN) of leptin (r = 0.65, p = 0.041) and with plasma glucose (r = 0.81, p = 0.015). In addition, the dietary intake/REE ratio was not only inversely related with LN leptin (-0.74, p = 0.037), but also with sTNF-R55 (r = -0.93, p = 0. 001) on day seven. In conclusion, temporary disturbances in the energy balance were seen during an acute exacerbation of COPD, related to increased leptin concentrations as well as to the systemic inflammatory response. Evidence was found that the elevated leptin concentrations were in turn under control of the systemic inflammatory response, and, presumably, the high-dose systemic glucocorticosteroid treatment.

Relationship of sputum color to nature and outpatient management of acute exacerbations of COPD

STUDY OBJECTIVES

To stratify COPD patients presenting with an acute exacerbation on the basis of sputum color and to relate this to the isolation and viable numbers of bacteria recovered on culture.

DESIGN

Open, longitudinal study of sputum characteristics and acute-phase proteins.

SETTING

Patients presenting to primary-care physicians in the United Kingdom. Patients were followed up as outpatients in specialist clinic.

PATIENTS

One hundred twenty-one patients with acute exacerbations of COPD were assessed together with a single sputum sample on the day of presentation (89 of whom produced a satisfactory sputum sample for analysis). One hundred nine patients were assessed 2 months later when they had returned to their stable clinical state.

INTERVENTIONS

The expectoration of green, purulent sputum was taken as the primary indication for antibiotic therapy, whereas white or clear sputum was not considered representative of a bacterial episode and the need for antibiotic therapy.

RESULTS

A positive bacterial culture was obtained from 84% of patients sputum if it was purulent on presentation compared with only 38% if it was mucoid (p < 0.0001). When restudied in the stable clinical state, the incidence of a positive bacterial culture was similar for both groups (38% and 41%, respectively). C-reactive protein concentrations were significantly raised (p < 0.0001) if the sputum was purulent (median, 4.5 mg/L; interquartile range [IQR], 6. 2 to 35.8). In the stable clinical state, sputum color improved significantly in the group who presented with purulent sputum from a median color number of 4.0 (IQR, 4.0 to 5.0) to 3.0 (IQR, 2.0 to 4. 0; p < 0.0001), and this was associated with a fall in median C-reactive protein level to 2.7 mg/L (IQR, 1.0 to 6.6; p < 0.0001).

CONCLUSIONS

The presence of green (purulent) sputum was 94.4% sensitive and 77.0% specific for the yield of a high bacterial load and indicates a clear subset of patient episodes identified at presentation that is likely to benefit most from antibiotic therapy. All patients who produced white (mucoid) sputum during the acute exacerbation improved without antibiotic therapy, and sputum characteristics remained the same even when the patients had returned to their stable clinical state.

COPD: exacerbation

A renewed interest in the clinical and pathogenic aspects of COPD exacerbation is timely in view of national and global COPD initiatives. The three big problems regarding COPD continue to be the following: prevention of the disease; slowing progression of the disease once diagnosis has been established; and prevention and more effective treatment of the so-called exacerbation. The following assessment will raise more questions than answers and will review some of the past and current concepts and contexts.