Study objectives: To compare the presenting features and outcome of patients with acute interstitial pneumonia (AIP) with other patients with diffuse alveolar damage (DAD) and with historical control subjects.
Design: Retrospective chart review.
Setting: A large, urban, teaching hospital.
Interventions: Patients were classified into idiopathic (AIP group) and secondary causes of DAD (ARDS group) according to available clinical and microbiology data. AIP and ARDS cases were compared, and ARDS cases were analyzed for long-term outcome.
Measurements and results: Twenty patients with pathologic diagnosis of DAD were identified. Four cases were excluded; eight cases of ARDS due to known etiologies were identified. These etiologies included pneumonia and sepsis (n = 6), cocaine use (n = 1), and carmustine chemotherapy (n = 1). Eight cases of AIP were found. When compared with the ARDS group, patients in the AIP group had a longer time from the onset of symptoms until hospital admission (16.8 ± 15.7 days vs 2.2 ± 1.0 days, p = 0.0015) and a shorter time from hospital admission to open-lung biopsy (8.3 ± 3.0 days vs 15.5 ± 9.5 days, p = 0.02) [mean ± SD]. Seven of eight patients with AIP and four of eight patients with ARDS survived to hospital discharge (p = not significant). The 12.5% mortality rate for patients with AIP reported in this series was significantly lower than the previously reported cumulative rate of 69.5% (p = 0.0025). Follow-up in five AIP survivors for a mean of 7.6 ± 3.5 years (range, 3 to 11 years) showed all to be without shortness of breath or relapse despite mild residual fibrosis on chest radiograph and mild-to-moderate restriction on pulmonary function tests (mean total lung capacity, 68.5 ± 6.2% predicted).
Conclusions: Our data support a favorable hospital and long-term outcome for patients with AIP, with no evidence of recurrence or progression to chronic interstitial lung disease.