Initial outpatient management of confirmed or presumed COP in adults

COP: cryptogenic organizing pneumonia; HRCT: high-resolution computed tomography; PFTs: pulmonary function tests (which include spirometry, lung volumes, and diffusing capacity); IBW: ideal body weight; CXR: chest x-ray.

* Clinical worsening is defined by worsening symptoms, new CXR opacities, or increased restriction on PFTs.

¶ We use Pneumocystis jirovecii prophylaxis when the prednisone dose is expected to equal or exceed 20 mg per day for longer than 4 weeks. Trimethoprim-sulfamethoxazole one double-strength (160 mg-800 mg) or one single-strength (80 mg-400 mg) tablet once daily is the preferred regimen; atovaquone (1500 mg once daily) is a reasonable alternative for those who cannot take trimethoprim/sulfamethoxazole.

Δ After resuming last well-tolerated prednisone dose, we reassess after three months and increase the prednisone dose if there is failure to improve. After stabilization for at least three months, a slower taper can be attempted. Three or more relapses suggests the need for long-term low-dose prednisone (≤10 mg/day) or initiation of a steroid-sparing agent, typically azathioprine or mycophenolate mofetil.

◊ In this setting, we typically obtain thiopurine methyltransferase (TPMT) levels prior to azathioprine initiation. For patients with normal TPMT activity or for whom TPMT activity is unknown, we start azathioprine 50 mg orally once daily and slowly increase the dose over two to four weeks to the target azathioprine dose of 1 to 2 mg/kg once daily (maximum 150 mg/day). The optimal dose in COP is unknown. Dose reduction is necessary in the setting of kidney disease. For patients with reduced TPMT activity, we prefer mycophenolate mofetil 1 to 1.5 g twice daily.