PURPOSE: A physiologic decline in spirometry meeting criteria for bronchiolitis obliterans syndrome (BOS) is sometimes transient. We sought to evaluate long term consequences of transient BOS physiology, and correlate CT findings.
METHODS: All lung transplant recipients with BOS physiology over a 15 year period were identified. The first FEV1 decrement below the BOS threshold was identified in all patients. Those patients who appeared to develop BOS (below the threshold for ≥3 weeks), but later rose above the threshold were categorized as “DeBOS.” If they subsequently declined again, they were categorized as “ReBOS.” CT results temporally related to the onset of BOS were abstracted and compared between sub-groups. Kaplan-Meier survival curves were applied to patient groups.
RESULTS: There were 267 lung transplant patients (63 bilateral, 204 single), of whom 140 (52.4%) qualified as having BOS. 106 BOS patients with contemporaneous CT’s were identified. The majority of CT scans were abnormal (67.9%). Of the 106 patients, 65 (61.3%) remained below the BOS threshold, while the remaining 41 (38.7%) subsequently increased above the BOS threshold (“DeBOS”). Only 4 of these patients remained above their BOS baseline, and 37 subsequently declined (“ReBOS”). All 106 patients were divided into 2 groups, typical BOS versus DeBOS/ReBOS. Comparing the two, median survival was significantly lower in patients with typical BOS than those with DeBOS/ReBOS (23.4 months v 49 months, p=0.007). Patients were then categorized into 5 groups based on physiology and imaging findings: BOS/normal CT; BOS/abnormal CT; DeBOS; DeBOS-ReBOS/normal CT; and DeBOS-ReBOS/abnormal CT. Median survival between these 5 patient categories was not significantly different (p=0.15).
CONCLUSIONS: In our cohort, patients with DeBOS-ReBOS physiology had an improved median survival. This suggests that even temporary, partial reversals of BOS physiology might indicate a disease phenotype with improved prognosis. While CT imaging is often clinically indicated, it does not appear to offer much prognostically.
CLINICAL IMPLICATIONS: In patients with BOS, fluctuations in spirometry are more predictive of survival than imaging.
DISCLOSURE: The following authors have nothing to disclose: Jacob Collen, Margaret Fregoso, Renee Brenner, Taylor Reffett, Anne Brown, Oksana Shlobin, Shahzad Ahmad, Merte Lemme, Steven Nathan
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