Disease activity and pretreatment, rather than hypogammaglobulinaemia, are major risk factors for infectious complications in patients with chronic lymphocytic leukaemia.

To identify patients at high risk of life-threatening infections, we retrospectively analysed the prevalence of infectious complications in 187 chronic lymphocytic leukaemia patients treated in our institution since 1999 and correlated them with clinical features. A questionnaire with detailed questions regarding infectious complications was mailed to patients and their general practitioners. Major infections (requiring intravenous antibiotics or inpatient treatment) were reported in 37 patients (19.8%) and minor infections (requiring oral antibiotics and outpatient treatment) in 113 patients (60.4%). Univariate analysis identified advanced disease (P = 0.02), gender (P = 0.01), duration of disease (P = 0.007), number of previous chemotherapy regimens (P < 0.001), previous therapy with purine analogues and monoclonal antibodies (P < 0.001; P = 0.019), massive splenomegaly (P = 0.03), low granulocyte count (P < 0.001), low serum immunoglobulin concentration (P = 0.005), low haemoglobin concentration (P < 0.001) and high serum lactate dehydrogenase (LDH) concentration (P < 0.001) as risk factors for major infections. In multivariable logistic regression analysis, only the number of previous chemotherapy regimens (risk ratio [RR] = 1.8; 95% confidence interval [CI] 1.2-8.0) and haemoglobin concentration (RR = 0.6; CI 0.5-0.8) remained significant for major infections. The number of previous chemotherapy regimens was the only independent risk factor for minor (RR = 7.6; CI 2.2-25.7) and varicella-zoster virus infections (RR = 2.1; CI 1.3-3.4). In untreated patients, the only risk factor for major infections was LDH concentration. Patients treated with purine analogues or autologous stem cell transplantation had a higher risk of developing viral infections. In conclusion, disease activity and pretreatment extent have a stronger impact on the risk of severe infectious complications than hypogammaglobulinaemia. Preferably, prophylactic strategies should be evaluated in patients defined by these parameters.