I. What every physician needs to know.
Bronchiolitis obliterans with organizing pneumonia (BOOP), originally described in 1985, is now more appropriately called cryptogenic organizing pneumonia (COP). It is one of the acute/subacute idiopathic interstitial pneumonias, along with Idiopathic Pulmonary Fibrosis and Acute Interstitial Pneumonia, among others.
COP is a rare pulmonary disorder characterized by dry cough, fever, dyspnea, and pulmonary infiltrates. The etiology is not thought to be infectious, and so it is usually recognized when a patient with presumed bacterial pneumonia does not respond to antibiotic therapy. COP is usually responsive to steroids. Pathologically, the disease begins with a proliferative bronchiolitis obliterans picture that progresses to organizing pneumonia.
II. Diagnostic Confirmation: Are you sure your patient has bronchiolitis obliterans with organizing pneumonia?
Lung biopsy is the only definitive method for diagnosing COP.
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A. History Part I: Pattern Recognition:
The key symptoms of COP are a persistent non-productive cough, exertional dyspnea, and flu-like symptoms (fever, malaise). The symptoms, which can be quite variable among patients, are usually present for fewer than 3 months before diagnosis is made. Because COP symptoms are quite similar to infectious pneumonia, the additional distinguishing feature is that the patient will have had no response to appropriate antibiotic therapy. Less common symptoms include sputum production, chest pain, arthralgias, and weight loss.
B. History Part 2: Prevalence:
Age of onset is most commonly between 50 and 70, although patients of all ages can be affected. A large proportion of cases are idiopathic, but secondary causes include various drugs (amiodarone, cocaine), connective tissue diseases (rheumatoid arthritis (RA), polymyositis), cancer (solid and hematologic malignancies), and transplants.
C. History Part 3: Competing diagnoses that can mimic COP:
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Bacterial pneumonia
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Adult respiratory distress syndrome (ARDS)
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Hypersensitivity pneumonitis
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Eosinophilic pneumonia
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Pulmonary diseases associated with connective tissue diseases
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Congestive heart failure
D. Physical Examination Findings.
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Crackles on lung exam (usually inspiratory)
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Cyanosis
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Wheezing (rarely)
E. What diagnostic tests should be performed?
1. What laboratory studies (if any) should be ordered to help establish the diagnosis? How should the results be interpreted?
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Erythrocyte sedimentation rate (ESR) & C-reactive protein (CRP) are usually markedly elevated
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White blood cell count is sometimes elevated
2. What imaging studies (if any) should be ordered to help establish the diagnosis? How should the results be interpreted?
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Chest X-ray will show bilateral diffuse alveolar opacities with a peripheral predilection.
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High-resolution chest computed tomography (HRCT) often is much more impressive than the chest x-ray would suggest, showing bilateral alveolar opacities in almost all patients. Rarely reticulonodular or mixed patterns are seen.
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Pulmonary function tests (PFTs) will show a mild to moderate restrictive pattern, though in some cases it will be normal or obstructive. Diffusing capacity of the lung for carbon monoxide (DLCO) is often reduced below 60% of predicted.
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Broncheoalveolar lavage and transbronchial biopsy are often non-diagnostic.
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Open or thorascopic lung biopsy is often required to make the diagnosis.
F. Over-utilized or “wasted” diagnostic tests associated with this diagnosis.
Contrast is not required for the HRCT.
III. Default Management.
Oral steroids are the mainstay of therapy. Most patients will make a full recovery with this treatment. For those who do not, progression to fibrosis often occurs.
A. Immediate management.
Pulmonary consultation is recommended to consider bronchoscopy, to guide therapy, and to follow response as an outpatient.
Once the diagnosis is made or highly suspected, begin steroids prednisone, 1 mg/kg. Steroids should be tapered very slowly over the course of 12 months and at the direction of a Pulmonologist.
Macrolide antibiotics can be used in mild cases.
Cyclophosphamide may be required in severe cases or in patients unable to tolerate steroids.
Lung resection may be considered if the process is focal rather than diffuse.
B. Physical Examination Tips to Guide Management.
Monitor lung exam for presence and disappearance of rales.
C. Laboratory Tests to Monitor Response To, and Adjustments in, Management.
A CXR should be repeated every few weeks.
D. Long-term management.
Steroids are tapered slowly over the course of 12 months. In improved patients, a relapse will present on chest X-ray before the patient is symptomatic and can be managed by increasing the steroid dose.
E. Common Pitfalls and Side-Effects of Management
Providers should monitor for typical side effects related to steroid and cyclophosphamide use.
IV. Management with Co-Morbidities
A. Renal Insufficiency.
No change in standard management.
B. Liver Insufficiency.
No change in standard management.
C. Systolic and Diastolic Heart Failure
No change in standard management.
D. Coronary Artery Disease or Peripheral Vascular Disease
No change in standard management.
E. Diabetes or other Endocrine issues
Patients with diabetes may require closer monitoring when steroids are prescribed.
F. Malignancy
Treat the underlying malignancy in order to properly manage the COP.
G. Immunosuppression (HIV, chronic steroids, etc).
If a patient develops COP while already being treated with immunosuppression, the prognosis is worse. These patients may require more aggressive immunosuppression with cyclophosphamide.
H. Primary Lung Disease (COPD, Asthma, ILD)
No change in standard management.
I. Gastrointestinal or Nutrition Issues
No change in standard management.
J. Hematologic or Coagulation Issues
No change in standard management.
K. Dementia or Psychiatric Illness/Treatment
No change in standard management.
V. Transitions of Care
A. Sign-out considerations While Hospitalized.
If the respiratory compromise is severe, patients may require parenteral steroids or cytotoxic agents. Idiopathic cases of COP usually respond to steroids, but short-term mechanical ventilation may be required until the response is seen.
B. Anticipated Length of Stay.
Anticipated length of stay is 3-7 days or more, depending on when the diagnosis is made and treatment is started. Since the most common diagnosis with similar presenting symptoms of COP is bacterial pneumonia, the correct diagnosis is often delayed.
C. When is the Patient Ready for Discharge.
Once the diagnosis has been made and the patient shows signs of respiratory stability, the remainder of the treatment and monitoring can be performed as an outpatient.
D. Arranging for Clinic Follow-up
1. When should clinic follow up be arranged and with whom.
General medicine and Pulmonary follow-up are required until the patient has completed the steroid course, and then on a regular basis thereafter.
2. What tests should be conducted prior to discharge to enable best clinic first visit.
A lung biopsy should be performed prior to discharge.
3. What tests should be ordered as an outpatient prior to, or on the day of, the clinic visit.
Pulmonary function tests should be done in order to assess response to therapy, but usually do not affect inpatient management.
E. Placement Considerations.
Patients usually can be discharged home unless there are comorbidities which require more intensive outpatient care.
F. Prognosis and Patient Counseling.
One-year mortality was 9.4% in one study. Relapse rate was 37.8% at 1 year.
VI. Patient Safety and Quality Measures
A. Core Indicator Standards and Documentation.
None.
B. Appropriate Prophylaxis and Other Measures to Prevent Readmission.
None.
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