Deep Learning Algorithm for Automated Cardiac Murmur Detection via a Digital Stethoscope Platform

Background

Clinicians vary markedly in their ability to detect murmurs during cardiac auscultation and identify the underlying pathological features. Deep learning approaches have shown promise in medicine by transforming collected data into clinically significant information. The objective of this research is to assess the performance of a deep learning algorithm to detect murmurs and clinically significant valvular heart disease using recordings from a commercial digital stethoscope platform.

Methods and Results

Using >34 hours of previously acquired and annotated heart sound recordings, we trained a deep neural network to detect murmurs. To test the algorithm, we enrolled 962 patients in a clinical study and collected recordings at the 4 primary auscultation locations. Ground truth was established using patient echocardiograms and annotations by 3 expert cardiologists. Algorithm performance for detecting murmurs has sensitivity and specificity of 76.3% and 91.4%, respectively. By omitting softer murmurs, those with grade 1 intensity, sensitivity increased to 90.0%. Application of the algorithm at the appropriate anatomic auscultation location detected moderate‐to‐severe or greater aortic stenosis, with sensitivity of 93.2% and specificity of 86.0%, and moderate‐to‐severe or greater mitral regurgitation, with sensitivity of 66.2% and specificity of 94.6%.

Conclusions

The deep learning algorithm’s ability to detect murmurs and clinically significant aortic stenosis and mitral regurgitation is comparable to expert cardiologists based on the annotated subset of our database. The findings suggest that such algorithms would have utility as front‐line clinical support tools to aid clinicians in screening for cardiac murmurs caused by valvular heart disease.

Registration

URL: https://clinicaltrials.gov; Unique Identifier: NCT03458806.

Interleukin-10 delivery via mesenchymal stem cells (MSC) to prevent ischemia/reperfusion injury in lung transplantation (141.46)

Ischemia-reperfusion injury (IR) is an important cause for lung graft loss (~30%). In this study, MSC & viral interleukin-10 (vIL-10) engineered MSC were tested for their ability to prevent lung IR injury. Bone marrow derived MSC from Lewis rat were transduced with rvIL-10-retrovirus & selected on neomycin. Following 120 min of left lung ischemia induction, Group A, rats received vIL-10-MSC (~15 x 106; i.v.); Group B, empty vector engineered MSC; Group C, MSC; Group D, saline; and Group E, no ischemia or MSC. Mean blood oxygenation (PaO2/FiO2 ratio, mmHg) was reduced (P<0.05) at 24h post-IR injury in Group B (138±86; n=9) & Group D (87±39; n=10), compared to MSC-vIL10 (353±105; Group A; n=10) group. By days 3 & 7 with MSC-vIL10 oxygenation was normal (475±55 & 435±33; n>9); by 4h it was 319±94 (n=7). MSC (passage ≤6) increased PaO2/FiO2 (454 ± 59; n=5) by 24h post-IR. Bronchoalveolar lavage at 24h post-MSC-vIL10 therapy reduced (P<0.05) granulocytes, CD4 & CD8 T cells. Lung injury score (histopathology) was higher (P<0.05) with no treatment (3.5 ± 1.3; n=5) compared to MSC-vIL10 (1.21± 0.6; n=7) & MSC (1.6±0.9; n=6) treated groups. Lung microvascular permeability & wet:dry ratio were lower (P<0.05) in MSC-vIL10 group. IL-1α, MCP-1α, MIP-1α, & IL1-β were increased in IR injured lung. ISOL (in situ staining for DNA fragmentation) & CASPACE-3 demonstrated reduced (p<0.05) number of apoptotic cells in MSC-vIL10 treated lungs. Ex vivo, expanded MSC were CD34-, CD31+ & CD45+ (5-10%), CD29+, CD90+ & CD44+ (65-95%), CD80 (0%), CD 86 (8%), MHC Class I+ (23-57%), & MHC Class II-. MSC & IL-10 delivery via MSC to prevent lung transplant IR injury seems promising.

Long-term complications of platinum-based chemotherapy in testicular cancer survivors

The purpose of this study was to describe the rates of cardiovascular and other medical complications related to the use of platinum-based chemotherapy in American testicular cancer survivors. The study sample consisted of 143 eligible long-term testicular cancer survivors. Participants were interviewed, their medical records were reviewed, and blood was obtained for cholesterol measurement during their follow-up visit. The mean follow-up time was 8.4 yr, and their mean age at follow-up was 41.2 yr; 72.7% had had non-seminoma, and 82.5% had received platinum-based chemotherapy. Hypertension rates in the platinum-treated group increased significantly from baseline to follow-up; however, once adjusted for blood pressure measurement (undiagnosed hypertension), no such increase was seen, and hypertension rates were already higher than national estimates at baseline in all groups. At the follow-up visit, the rates of hyperlipidemia (adjusted for measured cholesterol level) in both platinum- and non-platinum-treated groups (28.4% and 37.5%, respectively) were higher than national estimates (16.9%). Rates of coronary artery disease were higher in those who had received platinum and radiation (11.1%) than in those who had received platinum alone (4.3%), but this difference was not statistically significant. As suggested by previous studies, platinum-based chemotherapy may be associated with hypertension, hyperlipidemia, and coronary artery disease. However, our data suggest that undiagnosed hypertension and hyperlipidemia may be significant confounders, and we also observed a trend toward lower testosterone levels in participants who experienced cardiovascular complications.

Recipient Conditioning with Mesenchymal Stem Cells and Interleukin-10 Prolonged Cardiac Allograft Survival (102.1)

Mesenchymal Stem Cells (MSC) and viral interleukin-10 (vIL-10) have immunosuppressive properties. In this study, we tested their ability to prevent cardiac allograft rejection. Bone marrow derived MSC from Lewis rat were expanded ex vivo and transduced with rvIL-10-retrovirus. Autologous MSC or vIL-10 transduced MSC were injected (~25 x 106; i.v.) into irradiated (4 Gy) rat (RT1.Al). Six weeks later heterotopic heart (RT1.An) transplantation (Tx) was performed. MSC therapy prolonged (P<0.05) cardiac allograft survival (14±1 days; n= 4) compared to untreated controls (7±1 days; n=4). Also, vIL-10-MSC treatment prolonged (P<0.01) graft survival (38±1 days; n=6) compared to empty vector treated group (15±1 days; n=4). In vIL-10-MSC preconditioned animals that received donor bone marrow after heart Tx, graft survival was 22±2 days (n=8). Intragraft expression of co-stimulatory molecule (CD80) and cytokines (IL-2, IFN-γ) as determined by RT-PCR was lower (P<0.03) in vIL-10-MSC treated grafts compared to untreated control grafts. Ex vivo expanded MSC were CD34−, CD45+(5 %), CD29+(90%), CD80 (0%), CD 86 (8%), CD90+(93%), MHC Class I+(23–57%), and MHC Class II- as determined by FACS. Both vIL-10 and empty vector engineered MSC expressed CD29 (>95%) but not other molecules. The vIL-10-MSC produced ~ 6 ng/ml of vIL-10 ex vivo. vIL-10-MSC addition in MLR cultures inhibited lymphoproliferative response (P<0.05). TGF-β expression in stimulated (TNF-α or IL1-β) and unstimulated MSC was 46 – 65% of β-actin. IL-2, IL-4, IL-10, IFN-γ, and TNF-α expression was negligible in MSC (0–7% of β-actin). VEGF and HGF mRNA expression in MSC was 58% and 5% of β-actin, respectively. TgGFP+ MSC were demonstrable in various tissues for >28 days. Both MSC and vIL-10 conditioning to promote allograft survival seems promising.

Long-term complications of platinum in testicular cancer survivors

4589

Background: Long-term medical complications of platinum have become a major priority in the care of testicular cancer survivors. This study aimed to describe the prevalence of these complications from platinum-based therapy in American testicular cancer survivors. Methods: Testicular cancer survivors with no evidence of disease for at least 2 years were interviewed, had lab tests, and charts reviewed. Demographics, comorbidities, blood pressure, treatment, and outcomes were compared between all treatment modalities. NHANES 2002 and NHIS 2004 were used to obtain national estimates. Results: The mean age was 41 years; 72.7 % had nonseminoma, 96.5% had orchiectomy, 21.0% received radiation (XRT), and 82.5% platinum. The mean follow-up was 8.4 years. There was no statistical difference in the rates of Coronary Artery Disease (CAD), hyperlipidemia, hypertension (HTN), renal insufficiency (RI), or hypomagnesemia (see table ). There was a trend toward an increase in hyperlipidemia at follow-up compared to initial visit in all treatment groups but HTN increased only in those who did not receive platinum. Conclusion: Excluding HTN, we observed a trend toward an increase in the prevalence of RI, hypomagnesemia, hyperlipidemia, and CAD among patients who received platinum when compared to their baseline rates. Similar to a recent study by Huddart et al, we saw a trend toward higher risk of developing CAD in those who received both platinum and XRT. These findings suggest that hyperlipidemia and HTN may be more related to orchiectomy or the germ cell tumor itself than being a complication of platinum. Further prospective cohort studies with a larger group of survivors who have not received platinum are warranted to determine if HTN and hyperlipidemia are true complications of platinum-based chemotherapy.

[Table: see text]

No significant financial relationships to disclose.

Usefulness of catheter-directed thrombolysis using alteplase in peripheral vascular occlusion

This study evaluated the safety and efficacy of alteplase in catheter-directed treatment for peripheral arterial and venous thrombosis and considered the optimal dosing regimen. Forty-four patients (49 encounters) underwent transcatheter therapy using alteplase between January and November 1999. The most common indications for thrombolysis were peripheral arterial occlusion (PAO) and venous thrombosis (38 patients, 43 encounters). Each encounter was reviewed for indication, dosage of alteplase, duration of infusion, concomitant use of anticoagulation, degree of lysis, and complications. Patients were divided into low-dose (0.5 to 1.0 mg/hr), mid-dose (1.0 to 1.5 mg/hr), and high-dose (>1.5 mg/hr) groups. For PAO, there was no significant difference in the success rate between the 3 dose groups. A lower complication rate was achieved in the low-dose group. For venous thrombosis, there was no difference in the overall success or complication rates for each of the 3 groups. Partial lysis was achieved more readily in the mid and high-dose groups, but the risk of serious complications was greater. Overall, the complete thrombolysis rate was 71% for PAO and 55% for venous thrombosis. Major and minor complication rates were 7% and 19%, respectively. An equivalent success rate with a lower complication rate can be achieved using a low-dose constant catheter-directed infusion of alteplase for cases of PAO. Cases of venous thrombosis had a lower overall success rate compared with PAO. A mid-dose infusion of alteplase can achieve greater complete and partial thrombolysis rates without increasing the complication rate. Major and minor complication rates were similar to the rates given in the published literature.

Impact of HIV type 1 drug resistance mutations and phenotypic resistance profile on virologic response to salvage therapy

This study examines the association between presence of drug resistance mutations and phenotypic resistance at baseline to virologic response to salvage therapy in a community setting. The study population consisted of 58 antiretroviral drug-experienced patients with HIV-1 infection who had recently switched therapy because of virologic failure. Drug resistance mutations in the reverse transcriptase- and protease-coding regions and phenotypic susceptibility to 13 antiretroviral drugs were assessed at baseline. Plasma HIV-1 RNA levels were assessed at baseline and at subsequent clinic visits. Results showed that three variables were significant in predicting virologic response: HIV-1 levels at baseline, number of protease mutations, and phenotypic sensitivity score for the regimen at baseline. For four drugs there was a significant association between the presence of specific drug resistance mutations and >10-fold phenotypic resistance to that drug. With phenotypic resistance defined as >4-fold resistance, the association between specific drug resistance mutations and phenotypic resistance was significant for seven drugs. Overall, these data show that phenotypic susceptibility and absence of drug resistance mutations, particularly protease mutations, are significant predictors of virologic response. For several drugs, specific combinations of drug resistance mutations are associated with decreased phenotypic susceptibility and might provide useful clinical guidelines in selecting therapeutic options.

Pyruvate inhibits hepatic ischemia-reperfusion injury in rats

BACKGROUND

Ischemia/reperfusion (I/R) injury is a limiting factor in liver transplantation. We have recently shown that pyruvate (PY) inhibits intestinal and renal I/R injury. This study aims to evaluate the protective effect of PY on hepatic I/R injury.

METHODS

ACI rats were treated with PY, whereas control animals received placebo. Rats were killed after 60 min of partial hepatic ischemia and after 2, 6, 24, and 48 hr of reperfusion. For each time point, serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase were measured, and liver biopsy specimens were obtained to evaluate morphology, DNA fragmentation, and apoptosis (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling).

RESULTS

The survival rate 48 hr after I/R was 83% in the control group, and 100% in the PY-treated group (P>0.05). Increased enzymatic levels and histologic findings showed increased liver damage in the untreated group compared with PY. In control rats, apoptosis was enhanced after 1 hr of ischemia and peaked after 2 hr of reperfusion, to decrease gradually 48 hr after reperfusion; in the PY group apoptosis was delayed and reduced. After 1 hr of ischemia, the number of apoptotic nuclei was significantly increased in control livers compared with normal preischemic livers, whereas the number was significantly reduced by PY. After 2 hr of reperfusion, the maximum number of apoptotic cells was observed, whereas PY significantly reduced the amount of apoptotic cells (P<0.05). Apoptosis was delayed in PY-treated livers to 6 hr after reperfusion, peaking at a significantly lower count compared with placebo-treated controls (P<0.05).

CONCLUSION

These data indicate that PY has a protective effect on I/R injury of the liver.

[Validation of a scale for responsibility (Salkovskis Responsibility Scale)]

Appraisal of inflated responsibility for harm is the cornerstone of Salkovskis's cognitive theory for obsessive compulsive disorder. The aim of our study is to present the validation study of the French translation of the R scale. The present study compared 50 subjects with obsessive compulsive disorder, 37 patients suffering from social phobia and 183 control subjects on a responsibility questionnaire (R scale). The cognitive hypothesis of Obsessive Compulsive Disorder (OCD) specifies two levels of responsibility-related cognitions: responsibility assumptions (attitudes) and responsibility appraisals (interpretations). The R scale evaluates the responsibility assumptions. Such attitudes should reflect the more generalized tendency to assume responsibility in a given situation, particularly situations involving intrusions and doubts. It is possible that such assumptions may be less specific to OCD. The inclusion of social phobia subjects in the present study allows evaluation of the specificity of any findings to OCD. Patients were diagnosed and classified according DSM IV criteria. The control subjects were taken in the general population. No formal interview was conducted. The three groups were compared for sex, age and educational level. Before treatment, all the participants filled in the Responsibility Scale of Salkovskis (27 items), the Beck Depression Inventory (21 items), the Beck Anxiety Inventory and the Bouvard's Obsessive Compulsive Thoughts Checklist. The results indicate that the two anxious groups scored significantly higher than the control group on Beck Depression and Anxiety Inventories but no significant difference was observed between the two anxious groups. OCD patients scored significantly higher than both social phobic patients and control subjects on the Obsessive Compulsive Thoughts Checklist (OCTC). The social phobic group scored this checklist significantly higher than the control group. In sum, the three groups were different on obsessive compulsive thoughts. On the washing subscale of the Obsessive Compulsive Thoughts Checklist, the OCD patients differed significantly from the control group and the social phobia patients. No difference was observed between the social phobia subjects and the control group. On the two other subscales of the OCTC, the checking and the responsibility scales, the three groups were different: OCD patients scored significantly higher than both social phobic patients and control subjects; the social phobic patients scored higher than the control group. Results support the reliability (test retest) and the internal consistency of the questionnaire. Patients with obsessive compulsive disorder (OCD) and social phobia subjects had significantly elevated score on the total scale compared to control subjects. However social phobia patients did not differ from patients with OCD. So, the responsibility for harm, evaluated by the R-scale seems not to be specific of OCD. This finding does not support the results of two studies (28, 30). But these two studies compared OCD patients with an anxious group including panic disorder with agoraphobia, generalized anxiety disorder and social phobia. The correlations with a measure of OCD symptoms were higher than the correlations with anxiety and depression. Finally, the factor structure was only studied on the control group. The exploratory factor analysis indicates that the R scale is a two-dimensional scale, reflecting a need to prevent risks and the belief that one has power to harm. The first dimension is less specific to the pathology than the second. Only patients with OCD had significantly elevated score on the "need to prevent risks" compared to the non-clinical group. The two anxious groups differed on "the belief that one has power to harm" from the non-clinical group but social phobia patients did not differ from patients with OCD. In sum, the two subscales of the R scale did not discriminate OCD patients and social phobic subjects. Further research is needed to replicate the present findings and to confirm the two dimensions of the R scale. Overall, the results are consistent with the hypothesis that responsibility beliefs are important in the experience of obsessional problems. However, responsibility assumptions such as the belief that one has the power to harm are shared with social phobia.

[Etiology of asthma]

Asthma is a chronic inflammatory disease of the airways which occurs in genetically predisposed individuals. This common disease has an epidemic progression in western countries. Despite the identification of several candidate genes, genetic modifications cannot explain the recent increase in asthma prevalence and severity in the last forty years. Environmental factors are likely to be the cause of the progression of this epidemic inflammatory disease.

Note: dissolution of aerosol particles of budesonide in Survanta, a model lung surfactant

The effect of a pulmonary surfactant extract from bovine lung, Survanta, on the dissolution rate of aerosol particles of budesonide was determined. Aerosol particles of budesonide were generated from an ethanol solution, dried, and collected by a cascade impactor for characterization or by a liquid impinger for dissolution experiments. Powder x-ray diffraction, differential scanning calorimetry, differential thermal analysis, and scanning electron microscopy were used to characterize the aerosol particles and starting material. No change in phase was detected, although the aerosol particles appeared to contain residual solvent. The dissolution rate of the aerosol particles in saline was low and variable. Survanta increased the extent of dissolution of budesonide in proportion to the added concentration, which was also verified by equilibrium solubilization studies. Survanta also increased rate of dissolution, in a manner similar to sodium dodecyl sulfate. Analysis of the concentration of budesonide following ultracentrifugation indicated that there is rapid equilibration of budesonide between the Survanta and aqueous phase. These results show that lung surfactant has the potential of enhancing the rate and extent of dissolution of drugs administered to the lung.

Inhaled corticosteroids and Churg-Strauss syndrome: a report of five cases

Churg-Strauss syndrome is an eosinophil-associated, small vessel granulomatous vasculitis, characterized by late onset asthma, upper airways disease, eosinophilia, and clinical manifestations of systemic vasculitis. Several cases of Churg-Strauss syndrome have been recognized in patients treated with cysteinyl leukotriene-receptor antagonists and weaned off systemic corticosteroids. These cases have led to a general warning on the possible development of Churg-Strauss syndrome after taking cysteinyl leukotriene-receptor antagonists. The authors report five cases of Churg-Strauss syndrome in severe steroid dependent asthmatics in whom inhaled corticosteroids allowed systemic corticosteroid withdrawal. It is concluded that physicians should monitor patients carefully when severe asthma is controlled with any substance allowing withdrawal from (or even avoidance) of systemic corticosteroids. Case-control studies should identify more precisely the risk factors of Churg-Strauss syndrome.

Hydraulic high-pressure nebulization of solutions and dispersions for respiratory drug delivery

The purpose of this investigation was to assess hydraulic high-pressure nebulization as a means for respiratory drug delivery. A hydraulic high-pressure nebulizer was designed and constructed. In a design study, the output efficiency and the aerosol particle size were determined for the nebulizer as a function of nozzle diameter (5, 10, and 20 microns), gas flow rate (2 and 8 l/min), applied hydraulic pressure (2200 and 4000 psig), and distance between the nozzle orifice and impaction surface (0.25-4 cm) with an aqueous solution of fluorescein. The output efficiency was also measured with an ethanol solution and an aqueous phospholipid dispersion of liposomes. For the design study, each factor had an effect. The efficiency tended to increase with a decrease in the nozzle diameter, although the differences between the 5- and 10-micron nozzle were more sensitive to the air flow rate and nozzle-to-impaction-surface distance. Greater efficiencies were always obtained at the higher ancillary air flow rates. Operating the nebulizer at different pressures caused a change in the functional relationship between the efficiency and the nozzle-to-impaction-surface distance. For the 5-micron nozzle at high pressure, efficiency fell with increasing nozzle-to-impaction-surface distance, whereas for the data obtained with the 20-micron nozzle, the efficiency increased with nozzle-to-impaction-surface distance, with lower efficiencies obtained at the higher pressures. For the remaining observations made with the 5- and 10-micron nozzles, the efficiency as a function of nozzle-to-impaction-surface distance appeared to be variable. For the 5- and 10-micron size nozzle, there was no significant effect of the air flow rate, pressure, or nozzle-to-impaction-surface distance on the mass median aerodynamic diameter and geometric standard deviation. For the 20-micron size nozzle, the particles were not completely dried. Ethanol solutions gave somewhat higher efficiencies, whereas the phospholipid dispersion gave efficiencies comparable to the aqueous solutions nebulized under similar conditions. The efficiency of the hydraulic high-pressure nebulizer appears to be correlated with the calculated properties of the liquid jet. For respiratory drug delivery, the hydraulic high-pressure nebulizer provides reasonably high outputs of respirable particles independent of time from a single pass of liquid through the nebulizer.

Analysis of a diffusion dryer for the respiratory delivery of poorly water soluble drugs

PURPOSE

The purpose of this study was to analyze a diffusion dryer as a means to remove organic solvents from aerosol particles of poorly water soluble drugs.

METHODS

Aerosols of methanol, ethanol, and ethyl acetate were generated with an ultrasonic nebulizer, and inflow to outflow concentration ratio of vapor in a annular charcoal column was determined as a function of time by gas chromotography at two to four different airflow rates. In addition, the particle transmission efficiency was determined with an ethanol solution of the test compound, budesonide. The results were analyzed with equations originally developed for assessing the loss of drug from intravenous tubing along with independent measures of the adsorption isotherm of the vapors onto charcoal.

RESULTS

Aerosol production was relatively constant with time, and the transmission of solid particles through the column occurred with efficiency nearing 100%. The inlet to outlet vapor concentration ratio was adequately described by a model of three resistances in series composed of the inner tube, the screen mesh, and the charcoal bed.

CONCLUSIONS

The diffusion dryer was found to be satisfactory for the removal of methanol, ethanol, and ethyl acetate and the efficiency may be assessed from the adsorption isotherms on charcoal and the geometry of the dryer.

Infusion of donor leukocytes to induce tolerance in organ allograft recipients

To further enhance chimerism, 229 primary allograft recipients have received perioperative intravenous infusion of a single dose of 3 to 6 X 10(8) unmodified donor bone marrow (BM) cells/kg body weight. In addition, 42 patients have been accrued in a concurrent protocol involving multiple (up to three) sequential perioperative infusions of 2 x 10(8) BM cells/kg/day from day 0-2 posttransplantation (PTx). Organ recipients (n = 133) for whom BM was not available were monitored as controls. The infusion of BM was safe and except for 50 (18%), all study patients have optimal graft function. Of the control patients, allografts in 30 (23%) have been lost during the course of follow-up. The cumulative risk of acute cellular rejection (ACR) was statistically lower in the study patients compared with that of controls. It is interesting that, 62% of BM-augmented heart recipients were free of ACR (Grade > or = 3A) in the first 6 months PTx compared to controls. The incidence of obliterative bronchiolitis was also statistically lower in study lung recipients (3.8%) compared with the contemporaneously acquired controls (31%). The levels of donor cell chimerism were at least a log higher in the peripheral blood of majority of the study patients compared with that of controls. The incidence of donor-specific hyporeactivity, as determined by one-way mixed leukocyte reaction, was also higher in those BM-augmented liver, kidney, and lung recipients that could be evaluated compared to controls.

Synthesis and kinetics of cyclization of MHC class II-derived cyclic peptide vaccine for diabetes

Conformationally constrained cyclic peptides are known to be better vaccines because of their ability to mimic the native structure of a protein against which an immune response is sought. To test the hypothesis of using conformationally constrained, disease-associated, MHC-derived peptides as vaccines for the prevention of type I diabetes, a 22 amino acid nonobese diabetic(NOD) mouse MHC class II-derived synthetic peptide was cyclized by the formation of end-to-end disulfide bonds and used to prevent diabetes and insulitis in NOD mice. The peptide was synthesized by Fmoc chemistry and cyclized using two methods: a commercially available cyclizing resin (Ekathiox) and air oxidation. When a 10 m excess of resin was used, the Ekathiox yielded a substantial amount of cyclic peptide with few or no side reactions. The kinetics of cyclization by air oxidation at different temperatures indicated that increasing both temperature and pH decreased the cyclization time significantly. Air oxidation at pH 10 at 37-55 degrees C yielded the desired product within 2 h.

A prospective cost-consequence analysis of adding lamivudine to zidovudine-containing antiretroviral treatment regimens for HIV infection in the US

BACKGROUND

Healthcare resource use data were collected for 1 year as part of the CAESAR (Canada, Australia, Europe, South Africa) clinical trial, which evaluated the effect of adding lamivudine to treatment regimens containing zidovudine in patients with HIV infection. This study showed that lamivudine-containing regimens reduced HIV disease progression to AIDS or death, in addition to significantly reducing the number of hospital stays, unscheduled outpatient visits, and medications for HIV-related illness. Estimates of US unit costs for each healthcare service were derived from nationally representative data sources, and were used to determine the costs of treatment during the trial period for the treatment and control groups.

RESULTS

A cost-consequence analysis showed that, in addition to the health benefits associated with the lamivudine regimen, costs for treating HIV-related illness and adverse events were lower with the lamivudine regimen. The average decrease in costs per patient for the 1-year period ranged from $US1922 to $US2645, depending on the data source used to estimate hospital length of stay. The incremental cost of lamivudine therapy for the 1-year period was $US2293. The estimated difference in total costs for the 2 treatment regimens thus ranged from an increase of $US371 to a cost saving of $US353.

CONCLUSIONS

Our findings indicate that treatments which slow the progression of HIV infection have the potential to reduce the monthly costs associated with HIV-related illness and adverse events during the time period that progression is slowed.

Clinical significance of CMV-specific T helper responses in lung transplant recipients

BACKGROUND

Cytomegalovirus (CMV) disease continues to be a major problem for lung transplant patients who generate an inefficient immune response to control this viral infection. Both T helper and cytotoxic T cells are thought to play an important role in prevention and control of CMV disease. We investigated the clinical significance of CMV-specific memory responses in lung transplant recipients.

METHOD

Peripheral blood samples (140) were collected from 99 lung transplant recipients. Patients were grouped according to their pre-transplant CMV serological status as recipient/donor (R-/D+, 25 patients), 28 R+/D+ patients, 35 R+/D- patients and 11 R-/D- patients. Memory responses to CMV whole antigen, 5 CMV proteins, and tetanus toxoid (TT) were measured in a 6-day proliferative assay. Results were expressed as the stimulation index (SI = experimental cpm/background cpm), and were considered positive if the SI was >3 and the cpm values were over 1,000.

RESULTS

The frequency of positive CMV memory responses was similar in three groups: 64% for R-/D+, 63% for R+/D+ and 56% for R+/D- except for R-/D- (21%). The memory response to TT was similar for all four groups (70% of samples were positive). The level of responsiveness to individual CMV proteins was much higher in R+/D+ group (65%) than the other two groups (35% for R+/D-, and 31% for R-/D+). We determined the temporal relationship between the presence of CMV-specific memory responses and the diagnosis of CMV disease. In the R-/D+ group, 16 of 17 patients who had CMV disease eventually developed CMV-specific memory. In those patients (n = 3) who failed to develop CMV-specific T helper response for a prolonged time, all had recurrent CMV disease. In the R+/D+ group, 4 of 8 patients with CMV disease exhibited CMV-specific memory responses. Three of 4 patients in whom we observed a persistent absence of CMV-specific memory had multiple episodes of CMV pneumonitis. In the R+/D- group, only one of 4 patients with CMV disease had suppressed CMV-specific memory response after first episode of CMV pneumonitis and had recurrent disease.

CONCLUSION

In lung transplant recipients, the loss or persistent lack of CMV-specific memory following infection was associated with chronic CMV disease. These data suggest that monitoring T helper memory responses following primary CMV infection or after augmented immunosuppression for treatment of rejection may identify those patients at risk for morbidity associated with recurrent CMV disease.

Predicting short-term outcome in severely ill heart failure patients: implications regarding listing for urgent cardiac transplantation and patient selection for temporary ventricular assist device support

BACKGROUND

The purpose of this study was to determine which patients on a cardiac transplantation list required a ventricular assist device.

METHODS AND RESULTS

In a preliminary study, 26 patients with decompensated severe New York Heart Association class IV chronic heart failure were studied. Blood levels for sodium, hemoglobin, cytokines, neurohormones, and hemodynamics were obtained. During short-term follow-up of 40 days, 12 patients had undergone emergent implantation of a ventricular assist device (range 1-27 days, mean 5 days), 4 died (range 14-38 days, mean 26 days), and 5 were alive and receiving only medical therapy while waiting for a transplantation. In addition, five patients had undergone transplantation (range 5-29 days, mean 18 days, excluded from further analysis). Survival curves were constructed by comparing the incidence of death and the implantation of an emergent ventricular assist device in patients with values of a variable above or below the mean value (or median for nonnormally distributed data). There was a significantly greater incidence of death or need for a ventricular assist device in patients with higher levels of tumor necrosis factor-alpha (P = .008), lower levels of serum sodium and hemoglobin (P = .02 and P = .03, respectively), higher heart rates (P = .03), and higher plasma norepinephrine levels (P = .01). The Cox proportional hazards model demonstrated that only serum sodium (P = .03) independently predicted those patients who died or who required emergent left ventricular assist device.

CONCLUSION

Numerous variables, particularly serum sodium, need to be considered when evaluating which patients on the transplant list require early assist device implantation or urgent transplantation. These preliminary observations merit confirmation in a larger patient population.

Clinical relevance of in vitro propagation of activated lymphocytes from endomyocardial biopsy samples of pediatric heart transplant recipients

In vivo activated T-lymphocytes can be cultured from endomyocardial biopsy samples of human cardiac allografts, sometimes even in the absence of histological rejection. We investigated the clinical relevance of this "lymphocyte growth assay" in pediatric heart transplant recipients. Specifically, we wished to determine if: (i) positive lymphocyte growth from EMB samples in the absence of significant rejection identifies a patient as being at increased risk for the development of acute rejection; (ii) withdrawal or major dose reduction of corticosteroids in the presence of lymphocyte growth results in high risk of rebound rejection; and (iii) presence of lymphocyte growth during acute rejection helps predict the response to treatment. Cultures were performed on 789 consecutive EMB samples from 65 pediatric heart transplant recipients in media containing 30 U/ml of recombinant IL-2. T-lymphocytes were cultured from 16% of EMB samples with low grade rejection (grade 0-1b) and from 34% of EMB samples with grade 2-4 rejection. EMB samples obtained early post-transplant (<180 days) were significantly more likely to yield positive lymphocyte growth compared to biopsies obtained late for any given rejection grade. Lymphocyte growth was comparable between patients managed with cyclosporine or tacrolimus based immunosuppression. For 227 EMB samples without rejection, a subsequent EMB sample was obtained within 12 weeks. Lymphocyte cultures were positive in 47 of these 227 EMB samples (21%), and in 19 out of 47 (40%) cases acute rejection (grade 2-4) was present on the follow-up EMB sample. By contrast, of 180 biopsies without growth, only 29 (16%) showed rejection at the next EMB (p<0.0001). When a follow-up biopsy was performed within 12 weeks of corticosteroid withdrawal, "rebound rejection" was observed in 3 out of 10 (30%) cases where the previous EMB sample yielded positive lymphocyte growth and in 4 out of 38 (11%) cases when it did not (p=0.29). The presence of lymphocyte growth in association with rejection was also predictive of whether rejection would resolve following high dose intravenous corticosteroid therapy (persistent rejection in 33 out of 50 (66%) cases with positive growth, versus 25 out of 80 (31%) cases without growth (p<0.0001)). Thus, positive lymphocyte growth is strongly associated with higher grade of rejection and earlier time from transplantation. Lymphocyte growth in the absence of rejection indicates high risk for rejection within the next 12 weeks. Growth in association with acute rejection indicates high probability of persistence of rejection following treatment with high dose corticosteroids.