Soluble interleukin-2 receptor level as an indicator of liver allograft rejection.

We studied the serum levels of soluble interleukin-2 receptors (SIL-2R) in liver allograft recipients: a control group without rejection or CMV disease, a group with only rejection episodes, and a group with only cytomegalovirus disease. Rejection was diagnosed by the presence of compatible laboratory and histologic abnormalities and absence of other causes of graft dysfunction. CMV disease was diagnosed by isolation of CMV in blood or liver specimen cultures or identification of cytomegalic inclusions in the liver biopsy specimen. Of 82 consecutive recipients treated with cyclosporine and prednisone, 12 were in the control group, 20 in the rejection group, and 5 in the CMV disease group. The remaining 45 had other or multiple complications. In the control group the SIL-2R levels (determined by an ELISA) decreased by a mean of 4% per day after transplantation; in the rejection group the levels increased by a mean of 17% per day in the 10 days prior to the diagnosis of rejection; in the CMV disease group the levels tended to increase prior to the diagnosis of CMV disease. The rejection group had significantly higher SIL-2R levels than the control group at comparable times. Thus, SIL-2R levels were significantly increased at the time of allograft rejection compared with levels in a control group, and recipients with CMV disease had increased levels of SIL-2R but they were not as high as in recipients with rejection episodes.

Influence of positive lymphocyte crossmatch and HLA mismatching on vanishing bile duct syndrome in human liver allografts.

Among the first 52 recipients of primary liver allografts with follow-up of 2 weeks or greater, 6 patients had biopsy-confirmed vanishing bile duct syndrome (VBDS) and required retransplantation. Five of these six patients had positive lymphocyte crossmatches. Of the 46 remaining liver transplant recipients, 11 had positive crossmatches. Thus, the incidence of VBDS was 5/16 in recipients with a positive crossmatch and 1/36 in recipients with a negative crossmatch. The positive-crossmatch group was significantly more likely to develop VBDS than the negative-crossmatch group (P less than 0.004, log rank test). Additional HLA studies comparing degree of donor-recipient mismatch at the various HLA loci showed no significant difference between the groups for class I disparity. However, class II mismatch was of borderline significance (P less than 0.056). When evaluated individually, the DQ mismatch (P less than 0.04) appeared to be more important than the DR mismatch (P = NS). Our data suggest that a positive lymphocyte crossmatch and a class II mismatch, in particular HLA DQ disparity, may play an important role in the pathogenesis of VBDS.

Application of the Mayo primary biliary cirrhosis survival model to Mayo liver transplant patients.

Liver transplantation is considered lifesaving for selected patients with end-stage primary biliary cirrhosis (PBC). A mathematical model to predict survival in the patient with PBC who has not undergone transplantation would be valuable for improving selection of patients for and timing of transplantation and for providing control information for assessment of the efficacy of transplantation. The Cox regression method and data from 312 Mayo Clinic patients with PBC were used to develop a model based on age, total serum bilirubin, serum albumin, prothrombin time, and severity of edema. When cross-validated on an independent set of 106 Mayo patients, the model accurately predicted their survival. It was similar to two other published survival models in terms of risk measurement but had the advantage of not necessitating liver biopsy. The model was used to assess the efficacy of liver transplantation by comparing the Kaplan-Meier survival of 32 Mayo patients after transplantation with the average model prediction of survival without transplantation. Beyond 3 months after transplantation, Kaplan-Meier survival probabilities were significantly greater than control survival predicted by the model (P less than 0.001). Examples of using the model for aiding in selection of patients for and timing of transplantation are provided.

Intraoperative blood loss and patient and graft survival in orthotopic liver transplantation: their relationship to clinical and laboratory data.

We reviewed the records of 83 patients who underwent 100 orthotopic liver transplantations in order to determine the following: (1) the methods to predict blood usage, (2) the consequences of an ABO-incompatible transplant, (3) the benefit of providing cytomegalovirus (CMV)-negative blood products to CMV-negative patients receiving a liver from a CMV-negative donor, (4) the association of donor anti-hepatitis B core antigens and subsequent hepatitis B, and (5) the prognostic consequences of rouleaux observed in pretransplant blood compatibility testing. Patient diagnosis, the presence of ascites, a preoperative prothrombin time greater than 15 seconds, and a multifactorial "risk category" were all predictive of intraoperative blood loss. A history of previous gastrointestinal bleeding or an operation that involved the right upper abdominal quadrant was not predictive of intraoperative blood loss. Although CMV infection is common after liver transplantation, the prophylactic use of CMV antibody-negative blood products in CMV-negative recipients receiving a liver from a CMV-negative donor in our series was not associated with postoperative CMV infection. The transplantation of a liver positive for anti-hepatitis B core antigen was associated with subsequent hepatitis B surface antigen seroconversion in two of four cases. Transplantation of an ABO-incompatible liver and the presence of rouleaux observed in pretransplant blood compatibility testing were both associated with a significantly higher mortality. A careful review of laboratory data and medical records of patients undergoing liver transplantation should enhance the ability to modify the approach to the allocation of limited blood resources and the care and management of these patients.

A prospective pilot study evaluating the effectiveness of secretory IgA measurements in bronchoalveolar lavage to detect non-small cell lung cancer.

Previous studies have described significant elevations in the concentrations of secretory immunoglobulin A (sIgA) in bronchial washings obtained from cancerous lungs. To date, there have been no prospective investigations examining the predictive value of sIgA measurements in clinically relevant settings. Our goal was to determine if measurement of sIgA in bronchoalveolar lavage (BAL) at the time of bronchoscopic evaluation of potentially malignant lung nodules might prospectively predict the presence of cancer. We observed no significant increase in the sIgA obtained from eight BALs obtained from cancerous lungs as compared with BALs taken from these same patients' contralateral cancer-free lungs. We also saw no significant difference in BAL (sIgA) obtained from patients eventually found to have cancer (N = 8) as compared with those found to have noncancer diagnoses (N = 6). In light of these findings, we think it unlikely that measurement of sIgA will be clinically useful in the diagnosis of pulmonary malignant neoplasms.

Piecewise exponential survival curves with smooth transitions.

Several models of a population survival curve composed of two piecewise exponential distributions are developed. In one formulation the hazard rate changes at a point that is an unobservable random variable that varies between individuals. The population hazard function may decrease with age even when all individuals' hazards are increasing. In a second formulation, the population hazard function is modeled directly. Several models are fit to the survival history of a cohort of 5751 highly inbred male Drosophila melanogaster and the British coal mining disaster data.

Association between survival time and ordinal covariates.

An application of the method of rank correlation is proposed for testing independence between a censored survival time and an ordinal covariate. The test statistic counts the number of concordances minus the number of discordances at each time with event(s) and adds across times; it is expressible as a score statistic within the proportional hazards framework. The proposed test includes, as a special case, a generalization of Jonckheere's test against ordered alternatives and as applied to the analysis of categorical data, it can be seen as a generalization of the Mantel-Haenszel procedure.

The effects of transformations and preliminary tests for non-linearity in regression.

Non-linear relationships between two variables are often detected as a result of a preliminary statistical test for linearity. Common approaches to dealing with non-linearity are to (a) make a linearizing transformation in the independent variable or (b) fit a relationship that is non-linear in the independent variable, such as including a quadratic term. With either approach, the resulting test for association between the two variables can have an inflated type I error. We consider testing the significance of the quadratic term in a quadratic model as a preliminary test for non-linearity. Using simulation experiments and asymptotic arguments, we quantify the type I error inflation and suggest simple modifications of standard practice to protect the size of the type I error. In the case of quadratic regression, the type I error will be increased by roughly 50 per cent. The simple strategy of appropriately correcting the alpha-level is shown to have minimal loss of power if the relationship is truly linear. In the case of a linearizing transformation, the impact on the type I error will depend on the values of the independent variable and on the set of potential linearizing transformations considered. Simulation results suggest that a procedure which adjusts the test statistic according to the results of the preliminary test may offer adequate protection.