BMC Cancer 2009, 9:153 http://www.biomedcentral.com/1471-2407/9/153 Institute Common Toxicity Criteria Version 3 (NCICTC v 3)-https://webapps.ctep.nci.nih.gov/webobjs/ctc/web help/welcome_to_ctcae.htm). Several prognostic variables were evaluated for their impact on toxicity. These included age, sex, stage, per- formance status, plasma lactate dehydrogenase concentra- tion (LDH), type of chemotherapy used, presence of B symptoms, presence of bone marrow involvement on either aspirate or trephine, and use of G-CSF. The Interna- tional Prognostic Index was not used in analyses because it is a function of age, stage, performance status and LDH, all of which were included separately in multivariate modelling. For some variables data were unavailable on moderately large proportions of the original total of 784 patients; for example 12.4% for LDH, 15.1% for bone marrow tre- phine and 16.7% for bone marrow aspirate. Initially each variable was checked against sex, age, disease stage, per- formance status, type of chemotherapy and whether or not GCSF was given to determine whether there were any systematic differences in the distribution of missing data, but none was found. In addition, other variables were compared with the haematological toxicity measures in the same manner. The only association found was that patients with data missing on bone marrow aspirate and trephine also tended to have data missing on haematolog- ical toxicity. This may have arisen because of matters of policy or availability of these tests in some centres from which patients were drawn. Patients in this study were all aged 60 years or older. Age was dichotomized at 75 years because this is approxi- mately the point at which normal mortality begins to take effect in modern Western societies. The statistical significance of differences in contingency tables was assessed by the chi-squared test or Fisher's exact test. Odds ratios (OR) for contingency tables and their 95 per cent confidence intervals (CI) were calculated by logis- tic regression and their statistical significance was assessed by the Wald test. The level for statistical significance was p < 0.05. In multivariate modelling by logistic regression, all predictor variables having an association with an outcome variable with p < 0.1 were entered into an initial model which was then reduced by successive elimination of var- iables with p > 0.05. The provisional final model thus obtained was further examined by re-entering/removing every previously excluded variable separately until a model containing only variables with p < 0.05 resulted. Potential interactions between B symptoms and other var- iables were evaluated but no such effects were identified. Potential interactions among other variables were also explored but none having any material influence on the chosen final regression models were identified. As an additional check regarding missing data, for each final regression model, all patients who were excluded because of missing data on any variable in the model were com- pared with those who were included in relation to sex, age, disease stage, performance status, type of chemother- apy and whether or not GCSF was given, but no signifi- cant differences were found. It was concluded that the varying sub-sets of patients analysed were not unrepre- sentative of the total pool of 784 patients. Analyses were performed using SPSS Version 16 (SPSS Australasia Pty Ltd). Results Of the 784 patients in the original study the following were excluded sequentially: four with no information on stage of disease, 20 with no information on B symptoms, and 96 with no information on one or more of the hae- matological toxicity measures (anaemia, leucopenia, thrombocytopenia), leaving 664 patients for analysis, most of whom had complete data on most variables ana- lysed. The age and sex of patients, treatment groups, clin- ical characteristics at randomization, maximum haematological toxicity grades attained during treatment and frequency of toxicity symptoms are shown in Tables 1 and 2. The presence of B symptoms was associated with disease stages 3 or 4, performance levels 2–4, elevated LDH and positive bone marrow assessments (Table 3). In subsequent analyses patient age, disease stage, perform- ance status and the toxicity variables were dichotomized as shown in Table 4. Leucopenia In univariate analyses grade 3 or 4 leucopenia was signifi- cantly associated with the presence of B symptoms occur- ring in approximately 40% of patients without inflammatory symptoms compared with 58% of those with B symptoms (p < 0.001). Severe leucopenia also occurred more frequently in patients aged 75 years or older, having received PMitCEBO, having received GCSF, disease stage 3 or 4, performance status level 2 or higher, elevated LDH, positive bone marrow aspirate and positive bone marrow trephine (Table 4). There was no associa- tion with sex. The association between B symptoms and leucopenia persisted (OR 1.7, 95% CI 1.2–2.4) in multi- variate analysis after adjustment for age, performance sta- tus, bone marrow involvement, type of chemotherapy and receipt of GCSF, the latter having a protective effect (Table 5). Anaemia In univariate analyses grade 3 or 4 anaemia was signifi- cantly associated with the presence of B symptoms occur- ring in 10% of patients with B symptoms compared with 5% without (p = 0.011). Severe anaemia was also associ- Page 3 of 10 (page number not for citation purposes)