Data from 932 patients with leukemia who received bone marrow transplants were analyzed to determine factors associated with an increased risk of developing interstitial pneumonitis. Interstitial pneumonitis developed in 268 patients for a 2-year actuarial incidence of 35 +/- 4% (SD) and with a mortality rate of 24%. Six factors were associated with an increased risk: use of methotrexate rather than cyclosporine after transplantation (relative risk, 2.3; p less than 0.0002); older age (relative risk, 2.1; p less than 0.0001); presence of severe graft-versus-host disease (relative risk, 1.9; p less than 0.003); long interval from diagnosis to transplantation (relative risk, 1.6; p less than 0.002); performance ratings before transplantation of less than 100% (relative risk, 2.1; p less than 0.0001); and high dose-rates of irradiation in patients given methotrexate after transplantation (relative risk, 3.2; p less than 0.03). The risk of developing interstitial pneumonitis ranged from 8% in patients with none of these adverse risk factors to 94% in patients with all six. These findings may help to identify patients at high risk for this complication.

Acute graft-versus-host disease (GvHD) is an important complication of bone marrow transplantation in humans. Risk factors are imprecisely defined and controversial. We analysed data from 2036 recipients of HLA-identical sibling transplants for leukaemia or aplastic anaemia to identify risk factors for GvHD. Analyses indicate that grading of GvHD can be reproducibly divided into absent or mild versus moderate to severe; 2-year actuarial probability was 54% (95% confidence interval 52-56%) for absent or mild and 46% (44-48%) for moderate to severe. Factors predictive of development of moderate to severe GvHD include donor/recipient sex-match (female----male greater than others, relative risk 2.0, P less than 0.001). This risk was markedly increased if female donors for male recipients were previously pregnant or transfused (relative risk 2.9, P less than 0.0001). Older patients were at increased risk of GvHD (relative risk 1.6, P less than 0.001), but the age gradient was modest, even the youngest patients had a substantial risk of GvHD and, if parous or transfused female----male transplants were excluded, age was not a significant risk factor. Cyclosporine or methotrexate were equally effective at preventing GvHD and were superior to no prophylaxis (relative risk 2.3, P less than 0.01). These data should be useful in estimating the risk of acute GvHD in an individual patient and in designing clinical trials to investigate methods to modify or prevent GvHD.

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