Cost analysis of home monitoring in lung transplant recipients

OBJECTIVES

The University of Minnesota has maintained a home monitoring program for over 10 years for lung and heart-lung transplant patients. A cost analysis was completed to assess the impact of home monitoring on the cost of post-transplant medical care.

METHODS

Clinical information gathered with the monitoring system includes spirometry, vital signs, and symptom data. To estimate the impact of this system on medical costs, we completed a retrospective analysis of the effects of home monitoring on the cost of post-lung transplant medical care. The cost analysis used multivariate linear regression with inpatient, outpatient, and total medical care costs as the dependent variables. The independent variables for the regression include home monitoring adherence, underlying disease, ambulatory diagnostic group mapping variables, transplant type, and patient demographics.

RESULTS

The multivariate regression of the overall cost results predicts a 52.4 percent reduction in total costs with 100 percent patient adherence; this rate includes a 72.24 percent reduction in inpatient costs and a 46.6 percent increase in outpatient costs. The actual first year average patient adherence was 74 percent.

CONCLUSIONS

Adherence to home monitoring increases outpatient costs and reduces inpatient costs and provides an overall cost savings. The break-even point for patient adherence was 25.28 percent, where the net savings covered the cost of home monitoring. This is well within the actual first year adherence rates (74 percent) for subjects in the lung transplant home monitoring program, providing a net savings with adherence to home monitoring.

Novel insights into lung transplant rejection by microarray analysis

Gene expression microarrays can estimate the prevalence of mRNA for thousands of genes in a small sample of cells or tissue. Organ transplant researchers are increasingly using microarrays to identify specific patterns of gene expression that predict and characterize acute and chronic rejection, and to improve our understanding of the mechanisms underlying organ allograft dysfunction. We used microarrays to assess gene expression in bronchoalveolar lavage cell samples from lung transplant recipients with and without acute rejection on simultaneous lung biopsies. These studies showed increased expression during acute rejection of genes involved in inflammation, apoptosis, and T-cell activation and proliferation. We also studied gene expression during the evolution of airway obliteration in a murine heterotopic tracheal transplant model of chronic rejection. These studies demonstrated specific patterns of gene expression at defined time points after transplantation in allografts, whereas gene expression in isografts reverted back to that of native tracheas within 2 wk after transplantation. These studies demonstrate the potential power of microarrays to identify biomarkers of acute and chronic lung rejection. The application of new genetic, genomic, and proteomic technologies is in its infancy, and the microarray-based studies described here are clearly only the beginning of their application to lung transplantation. The massive amount of data generated per tissue or cell sample has spawned an outpouring of invention in the bioinformatics field, which is developing methodologies to turn data into meaningful and reproducible clinical and mechanistic inferences.

Effect of preoperative pulmonary artery pressure on early survival after lung transplantation for idiopathic pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is the second largest indication for lung transplantation worldwide. Average 90-day mortality rates for this procedure are 22%. It is unclear what factors predispose patients with IPF to this increased early posttransplant mortality. Pulmonary hypertension may increase the risk of development of early posttransplant complications through several mechanisms. We examined the effect of secondary pulmonary hypertension on 90-day mortality after lung transplantation for IPF.

METHODS

An International Society for Heart and Lung Transplant Registry cohort study of 830 patients with IPF transplanted from January 1995 to June 2002 was undertaken. Risk factors were assessed individually and adjusted for confounding by a multivariable logistic regression model.

RESULTS

In the univariate analysis, pulmonary hypertension and bilateral-lung transplantation were significant risk factors for increased 90-day mortality. Multivariate analysis confirmed that mean pulmonary artery pressure and bilateral procedure remain independent risk factors after adjustment for potential confounders. Recipient age, ischemia time, cytomegalovirus status mismatch, and donor age were not independent risk factors for early mortality.

CONCLUSIONS

Bilateral-lung transplantation carries a greater risk of early mortality than single-lung transplantation for IPF. Increasing pulmonary artery pressure is a risk factor for death after single-lung transplantation in IPF. Mean pulmonary artery pressure should be included in the overall risk assessment of patients with IPF evaluated for lung transplantation.

Validation of the Proposed International Society for Heart and Lung Transplantation Grading System for Primary Graft Dysfunction After Lung Transplantation

BACKGROUND

A scoring system was recently proposed to grade the severity of primary graft dysfunction (PGD), a frequent early complication of lung transplantation. The purposes of this study are to: (1) validate the PGD grading system with respect to patient outcomes; and (2) compare the performance of criteria employing the arterial oxygenation to fraction of inspired oxygen (P/F) ratio to an alternative grading system employing the oxygenation index (OI).

METHODS

We retrospectively reviewed the medical records of 402 patients having undergone lung transplantation at our institution from 1992 through 2004. The ISHLT PGD grading system was modified and grades were assigned up to 48 hours post-transplantation as follows: Grade 1 PGD, P/F > 300; Grade 2, P/F 200 to 300; and Grade 3, P/F < 200. A worst score T(0-48) was also assigned, which reflects the highest grade recorded between T0 and T48.

RESULTS

The prevalence of severe PGD (P/F Grade 3) declined after transplant, from 25% at T0 to 15% at T48. Grouping patients by P/F grade at T48 demonstrated the clearest differentiation of 90-day death rates (Grade 1, 7%; Grade 2, 12%; Grade 3, 33%) (p = 0.0001). T48 OI grade also differentiates 90-day death rates. There was no difference in longer-term survival between patients with PGD Grades 1 and 2. OI grade at T0 qualitatively improved differential mortality between Grades 1 and 2; however, the differences did not reach statistical significance. Patients with a worst score T(0-48) of Grade 3 PGD did have significantly decreased long-term survival, as well as longer ICU and hospital stay, when compared with Grades 1 and 2 PGD. Significant risk factors for short- and long-term mortality in our multivariate model were P/F Grade 3 [worst score T(0-48) as well as T0 grade], single-lung transplant, use of cardiopulmonary bypass and high pre-operative mean pulmonary artery pressure.

CONCLUSIONS

There is an increased risk of short- and long-term mortality and length of hospital stay associated with severe (Grade 3) PGD. The proposed ISHLT grading system can rapidly identify patients with poor outcomes who may benefit from early, aggressive treatment. Refinement of the scoring system may further improve patient risk stratification.

Analysis of chronic lung transplant rejection by MALDI-TOF profiles of bronchoalveolar lavage fluid

While lung transplant is an effective therapy for advanced lung disease, chronic allograph rejection remains a primary basis for lower survival rates than those for other solid organ transplants. This study used carefully controlled Zip-Tip extraction of bronchoalveolar lavage fluid (BALF) followed by MALDI-TOF MS to identify biomarkers of chronic lung transplant rejection. Many differences were observed between controls, those who did not develop chronic rejection within 100 months, and patients who had developed chronic rejection, diagnosed as bronchiolitis obliterans syndrome (BOS). Intensity ratios of peaks within the same MALDI-TOF profile were used to quantify the result. One of the best identifiers of BOS was a lowered ratio of clara cell protein (CCP m/z = 15,835) to lysozyme (m/z = 14,700), which gave 94% specificity and 74% sensitivity for diagnosis. Furthermore, low values for CCP/Lysozyme (<0.3) were observed in 66% of samples taken at 1 to 15 months prior to the diagnosis of BOS. Many other components of the profile gave similar or better outcomes for diagnosis but tended to be less valuable for the prediction of future disease. Overall, this study demonstrated the feasibility of this approach for the detection of disease biomarkers.

Allograft Rejection After Lung Transplantation

Lung transplantation has become an accepted therapy for selected patients with advanced lung disease. One of the main limitations to successful lung transplantation is rejection of the transplanted organ. This article discusses the clinical presentation, treatment, and prevention of hyperacute, acute, and chronic rejection in the lung transplant recipient.

Colon and rectal complications after heart and lung transplantation

BACKGROUND

Gastrointestinal complications of solid organ transplantation have been well described, but little attention has been paid to colorectal disorders in particular. The purpose of this study was to identify the incidence and severity of colorectal complications among a large cohort of heart and lung transplant recipients.

STUDY DESIGN

We reviewed the medical records of heart, lung, and heart-lung transplant recipients at a single institution between 1978 and 2004. Complications were identified based on need for consultation, endoscopy, or operation by a colorectal surgeon after transplantation.

RESULTS

Of 1,012 patients who received transplantations (530 heart, 435 lung, 47 heart-lung), 56 patients (6%) required evaluation for 84 colorectal problems. Incidence of complications was 7% in lung transplant recipients, 6% in heart-lung transplant recipients, and 4% in heart transplant recipients. Forty-four events (52%) were considered major (diverticulitis, perforation, malignancy, and other) and 40 (48%) were minor (polyps, pseudo-obstruction treated medically or endoscopically, benign anorectal disease, and other). Twenty-three (27%) required colectomy and 9 (10%) necessitated anal operation. Thirty-six (43%) required less-invasive interventions (endoscopy, minor anorectal procedures, and other). Eighteen (21%) were treated with medical therapy alone. Six patients died from colorectal disease (7%).

CONCLUSIONS

Colorectal complications are a considerable source of morbidity and mortality after heart and lung transplantation. These complications occur more frequently in patients who undergo lung and heart-lung transplantation as compared with heart transplantation alone.

Gene expression profiling in murine obliterative airway disease

Lung and heart-lung transplantation are effective treatments for many diseases unresponsive to other therapy. However, long-term survival of recipients is limited by the development of obliterative bronchiolitis (OB). In this study, microarray analysis of a heterotopic mouse model of obliterative airway disease (OAD) was used to test the hypothesis that the expression and patterns of genes will correlate with specific changes in tracheal tissue developing a response to allotransplantation and the infiltrating cells manifesting these changes. Expression profiles observed were in accordance with the current paradigm of a predictable sequence of events, beginning with airway injury; an innate immune response followed by an adaptive immune response, including both cell-mediated and humoral components; and eventual loss of airway epithelial cells. These observations confirm and expand the list of genes and molecular processes that can be studied as potential surrogate markers or targets for intervention of OB.

Incomplete Event Documentation in Medical Records of Lung Transplant Recipients

Context

The medical record is frequently used in clinical studies as a source of information on illness events experienced by patients; however, it may be incomplete.

Objective

To estimate the extent of incompletely documented acute bronchopulmonary events in a transplant clinic medical record at a single university medical center, using home monitoring data.

Design, Setting, and Subjects

Trends in daily home monitoring data were compared to contemporaneous medical record documentation at 150 different times in 30 lung transplant recipients over 45 subject-years.

Outcome Measure

Proportion of acute bronchopulmonary illness events documented in clinic medical record.

Results

By using home monitoring data in a new way, we found that 40% of events actually suffered by lung recipients could not be ascertained to have occurred from the clinic medical record alone. All missed encounters occurred away from the transplant clinic, and involved hospitalizations and telephone prescriptions.

Conclusions

Using the clinic medical record alone to identify acute bronchopulmonary events in lung transplant recipients may result in missing 40% of events. This has important ramifications for studies relying on the medical record for acute event ascertainment in lung transplantation and possibly other chronic diseases.

Decision support for the triage of lung transplant recipients on the basis of home-monitoring spirometry and symptom reporting

Purpose The objective of this study was to develop and evaluate a computerized rule-based decision support algorithm for nursing triage of potential acute bronchopulmonary events in lung transplant recipients on the basis of home monitoring of spirometry and symptoms. Methods The algorithm automatically separates recipients into 2 groups: those who are stable or improving and those who should be "watched" further because of their potential for developing bronchopulmonary events according to their weekly home-monitoring measurements. A total of 155 recipients (82 females and 73 males) contributed 1944 weekly records for the training (420), testing (786), and prospective evaluation (738) data sets. Weekly records contained daily values of forced expiratory volume at 1 second and respiratory symptoms, which were the inputs for the triage rules. Results Sensitivity and specificity were greater than 90% for the prospective evaluation comparing the computer decision support system with the manual nurse review of the same home-monitoring reports. Conclusions Algorithm performance in identifying lung recipients who should be placed on a "watch" list for the potential to develop acute bronchopulmonary events is comparable to the standard human clinical review of the same weekly home-monitoring data.

Medium-term results of extracorporeal membrane oxygenation for severe acute lung injury after lung transplantation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has been used successfully for early, severe reperfusion injury after lung transplantation. The purposes of this study are to: (1) document the medium-term survival of patients treated with ECMO; and (2) assess the extent of recovery of their pulmonary function.

METHODS

We retrospectively reviewed charts of 172 patients having lung transplants at our institution from 1997 through 2002. The group included 16 patients (9% of total; 10 bilateral, 5 single, 1 living lobar) treated with ECMO for primary allograft failure after single or bilateral single-lung transplantation. Survival and bronchiolitis obliterans syndrome (BOS)-free survival rates were calculated. Pulmonary function was assessed at 2 months, 1 year and 2 years post-transplant.

RESULTS

Median hospital stay was 48 days for the ECMO group and 16 days for the overall group (p < 0.05). The 90-day survival was 60% in the ECMO group, and 90% in the overall group. The 2-year survival was 46% in the ECMO group, and 69% in the overall group. Mean forced expiratory volume in 1 second (FEV(1)) in the ECMO group at 1 year was 59 +/- 13% of predicted, and at 2 years 60 +/- 15% of predicted; it was not significantly different for the overall group.

CONCLUSIONS

Patients treated with ECMO for primary allograft failure after lung transplantation showed acceptable medium-term survival and pulmonary function.