Effect of laminar air flow and building construction on aspergillosis in acute leukemia patients: a retrospective cohort study

BACKGROUND: The preventive effect of laminar air flow (LAF) on aspergillosis has been observed in patients with hematological malignancies. However, the short follow-up period limits the interpretation of study results. METHODS: To assess the preventive effect of long-term LAF use on aspergillosis in its long-term use, we retrospectively analyzed 124 acute leukemia patients at our hospital between January 2005 and March 2016. We compared the incidence of aspergillosis before (May 2008) and during the construction of a new building (June 2008–January 2010) and in the early (February 2010–March 2014) and late (April 2014–March 2016) periods after moving to a new hematology ward with an LAF system. The 2008 European Organization for Research and Treatment of Cancer and Mycosis Study Group criteria were used for the diagnosis of aspergillosis. RESULTS: Fourteen patients were diagnosed with possible, probable, or definite aspergillosis. Cumulative incidence rates of aspergillosis at day 180 were 12.4, 24.9, 9.3, and 25.1% before construction, during construction, in the early period after moving to a new ward, and in the late period after moving to a new ward, respectively (p = 0.106). Multivariate analysis showed that the LAF system tended to reduce the risk of aspergillosis in the early period (before construction vs. early period; hazards ratio (HR) = 1.97, p = 0.463 and during construction vs. early period;HR = 3.42, p = 0.184), but the risk increased in the late period (late vs. early period, HR = 5.65, p = 0.035). CONCLUSIONS: Building construction might increase the risk of aspergillosis. Short-term LAF use might reduce aspergillosis risk, but its long-term use is inadequate, although we could not exclude the possibility of increased risks in the recent period due to continued improvements in the different areas of our hospital. Strict maintenance, more effective LAF system, and optimization of aspergillosis prophylaxis may be necessary.