Chest
Volume 117, Issue 6, June 2000, Pages 1638-1645
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Clinical Investigations
COPD
Relationship of Sputum Color to Nature and Outpatient Management of Acute Exacerbations of COPD

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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.

Section snippets

Materials and Methods

Patients presenting to their primary-care physicians with acute exacerbations associated with sputum production and underlying diagnoses of COPD were considered for the study. All had a history of chronic bronchitis (daily sputum production for at least 3 months of 2 consecutive years) and the development of new symptoms with sputum production that led to a consultation with their general practitioner. These new symptoms included increased dyspnea, cough, sputum volume, sputum purulence,

Results

Of the 148 patients referred during the 15 months of the study, 1 patient was not entered in to the study because clinical review indicated the presence of pneumonia. Three patients were withdrawn within 7 days because of noncompliance, 3 refused entry, 6 were unable to provide a suitable sputum sample for analysis, and 14 were not entered because it was believed that they would be unable to comply with the study or had received recent (in the previous 4 weeks) changes in therapy. The

Discussion

The verification of a bacterial cause of an acute exacerbation of COPD is difficult. Undoubtedly, bacteria play a role, although it requires large studies or meta-analysis to demonstrate that antibiotics influence outcome.19 This is hardly surprising, because many exacerbations will not have a bacterial origin, and even when they do, spontaneous resolution can occur.

Previous authors have suggested that the presence of > 25 neutrophils/low-power field20 or a positive Gram's stain21 indicates a

Conclusions

In summary, we believe that acute exacerbations of COPD are heterogeneous as described in the extensive study by Macfarlane and colleagues28 and the review by Madison and Irwin.12 Subdivision of the exacerbations by sputum color identifies a group in whom recovery occurs without antibiotic therapy. The presence of mucoid sputum should be confirmed, however, as 15 of the patients (40%) subjectively reported that the color had changed. Comparison with a color chart indicated that this was to

References (28)

  • A McCormick et al.

    Morbidity statistics from general practice: fourth national study 1991–1992

    (1995)
  • NM Siafakas et al.

    Optimal assessment and management of chronic obstructive pulmonary disease (COPD)

    Eur Respir J

    (1995)
  • BTS guidelines for the management of chronic obstructive pulmonary disease

    Thorax

    (1995)
  • MB Nicotra et al.

    Antibiotic therapy of acute exacerbations of chronic bronchitis

    Ann Intern Med

    (1982)
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    Supported by an educational grant provided by Glaxo Wellcome plc.

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